2018 Comprehensive Stormwater Plan

CITY OF MOUNTLAKE TERRACE Comprehensive Stormwater Plan

G&O #17507 November 2018

TABLE OF CONTENTS CHAPTER 1 – INTRODUCTION WHAT IS THE COMPREHENSIVE STORMWATER PLAN? ...................................................... 1-1 MAJOR STORMWATER PROJECTS SINCE THE LAST PLAN .................................................... 1-1 WHY PLAN NOW? ............................................................................................................. 1-2 WHAT IS STORMWATER MANAGEMENT? ......................................................................... 1-2 WHAT ARE THE GOALS OF THE STORMWATER PROGRAM? ............................................... 1-3 WHAT ARE THE STORMWATER PROBLEMS? ...................................................................... 1-3 WHAT ARE THE RECOMMENDED ACTIONS? ...................................................................... 1-4 WHERE DOES THE FUNDING COME FROM? ..................................................................... 1-4

CHAPTER 2 – KNOWN ISSUES AND SOLUTIONS INTRODUCTION ................................................................................................................. 2-1 Stormwater Concerns ........................................................................................... 2-1 Potential Solutions ................................................................................... 2-1 Field Identified Problems ..................................................................................... 2-2 High Priority Issues.................................................................................. 2-2 Issue Classification .................................................................................. 2-4 Potential Solutions ................................................................................. 2-11 Water Quality ..................................................................................................... 2-11 Pollutant Sources ................................................................................... 2-11 Total Maximum Daily Loads Program .................................................. 2-13 Lake Ballinger ........................................................................................ 2-13 Potential Solutions ................................................................................. 2-14

CHAPTER 3 – STORMWATER MANAGEMENT PROGRAM EVALUATION AND RECOMMENDATION INTRODUCTION ................................................................................................................. 3-1 Potential New stormwater Policy and/or code ..................................................... 3-1 Operation and Maintenance ................................................................................. 3-1 Maintenance Standards ............................................................................ 3-7 National Pollutant Discharge Elimination system (NPDES) ............................... 3-9 Permit Requirements ................................................................................ 3-9 Stormwater Management Program Plan ................................................ 3-10 Public Education and Outreach/Public Involvement and Participation . 3-10 Illicit Discharge Detection and Elimination .......................................... 3-11 Controlling Runoff from New Development, Redevelopment and Construction Sites ............................................................................ 3-11 Municipal Operations and Maintenance ................................................ 3-12 Monitoring and Assessment ................................................................... 3-12 Reporting Requirements ........................................................................ 3-12 Recommended NPDES Permit Program ............................................... 3-13

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CHAPTER 4 – IMPLEMENTATION PLAN INTRODUCTION ................................................................................................................. 4-1 CAPITAL IMPROVEMENT PLAN ........................................................................................ 4-1 6-Year CIP Projects ............................................................................................. 4-2 Stream .................................................................................................................. 4-2 S1: Ballinger Park/Hall Creek Analysis and Improvement Projects ...... 4-2 S2: Hall Creek Hydrologic and Hydraulic Analysis ............................... 4-3 S3: Hall Creek Flood Abatement Project................................................ 4-3 Access .................................................................................................................. 4-3 A1: Police Station Stormwater Pipe Replacement.................................. 4-3 Structural .............................................................................................................. 4-4 ST1: 56th Avenue West Area Stormwater Replacement Projects ........... 4-4 Capacity ............................................................................................................... 4-4 C1: 66th Avenue West Pipe Replacement ............................................... 4-4 Pond ..................................................................................................................... 4-4 P1: Taylor Pond Rehabilitation............................................................... 4-4 P2: Cedar Way Dam Pond Rehabilitation .............................................. 4-5 Rate Study ............................................................................................................ 4-5 R1: Stormwater Rate Study .................................................................... 4-5 Annual Infrastructure Replacement ..................................................................... 4-6 AN1: Spot Repair Program ..................................................................... 4-6 AN2: Road-Related Upgrade Program ................................................... 4-6 AN3: Aging Infrastructure Replacement Program ................................. 4-6 20-Year CIP Projects ......................................................................................... 4-10 FINANCIAL PLAN ............................................................................................................ 4-15 Current Charges and Connections ..................................................................... 4-15 Service Charge Determination ........................................................................... 4-16 Preliminary Rate Analysis ................................................................................. 4-18 Grant and Loan Programs .................................................................................. 4-27 Public Works Trust Fund ....................................................................... 4-27 Department of Ecology Water Quality Combined Funding Program ... 4-27 Debt Financing ................................................................................................... 4-28

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LIST OF TABLES No.

Table

2-1 2-2 2-3 2-4 3-1

Field Identified Problems ..................................................................................... 2-6 Pollutant Sources and Impacts ........................................................................... 2-12 Potential Solutions for Pollutant Sources .......................................................... 2-14 Potential Structural Related Water Quality Tools ............................................. 2-17 City of Mountlake Terrace Recommended Operation and Maintenance Program .......................................................................................................... 3-3 Recommended NPDES Phase II Permit Program Hours (NonMaintenance)................................................................................................ 3-14 6-Year Capital Improvement Plan Projects ......................................................... 4-7 Pipe Replacement Costs per Linear Foot ........................................................... 4-10 20-Year Capital Improvement Projects(1) .......................................................... 4-11 Stormwater Utility Monthly Billing Charges .................................................... 4-15 Financial Forecast Assumptions ........................................................................ 4-17 10-Year Financial Forecast Analysis (2019-2028) ............................................ 4-19 20-Year Financial Forecast Analysis (2029-2038) ............................................ 4-22

3-2 4-1 4-2 4-3 4-4 4-5 4-6 4-7

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LIST OF FIGURES No.

Figure

1-1 1-2 1-3 1-4 2-1 2-2 2-3 2-4 2-5

Vicinity Map ........................................................................................................ 1-2 Critical Areas and Topography ............................................................................ 1-2 Drainage Basins ................................................................................................... 1-2 Drainage Base Map .............................................................................................. 1-2 Issue #1 ................................................................................................................ 2-2 Issue #2 ................................................................................................................ 2-2 Issue #3 ................................................................................................................ 2-2 Issue #4 ................................................................................................................ 2-2 Flooding of 216th Street and 68th Avenue West during a 2-Year Storm (December 19, 2017) ..................................................................................... 2-3 Issue #5 ................................................................................................................ 2-4 Issue #6 and #7..................................................................................................... 2-4 Known Issues ....................................................................................................... 2-4 6-Year CIP Locations .......................................................................................... 4-2 Ballinger Park/Hall Creek (CIP S1) ..................................................................... 4-2 Hall Creek Hydrologic and Hydraulic Analysis and Projects (CIP S2/S3) ......... 4-4 Police Station Stormwater Replacement (CIP A1) .............................................. 4-4 56th Avenue West Stormwater Replacement Projects (CIP ST1) ........................ 4-4 66th Avenue West Pipe Replacement (CIP C1) ................................................... 4-4 Taylor Pond Rehabilitation (CIP P1) ................................................................... 4-6 Cedar Way Dam Pond Rehabilitation (CIP P2) ................................................... 4-6

2-6 2-7 2-8 4-1 4-2 4-3 4-4 4-5 4-6 4-7 4-8

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APPENDICES Appendix A – Cost Estimates

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CHAPTER 1 INTRODUCTION The City of Mountlake Terrace, located in south Snohomish County within the Seattle metropolitan area (see Figure 1-1), is a community of residential (30 percent), commercial (nine percent), and business (four percent) land uses. The remaining 57 percent of land area is open space, public facilities, or is transportation related. Rapid growth occurred following the City’s incorporation in 1954 and continued into the 1960s as Mountlake Terrace became a commuter town. Small businesses flourished during this period. A Town Center Plan was adopted in 2007 and is scheduled for an update in 2018, to reflect changes over the past 11 years. A Sound Transit light rail station in Mountlake Terrace opening in 2024 is anticipated to increase economic viability and growth. Part of planning for this growth is developing the City’s stormwater management and infrastructure. “Stormwater” is rain or snowmelt that runs off hard surfaces, such as rooftops, paved streets, and parking lots.

WHAT IS THE COMPREHENSIVE STORMWATER PLAN? Mountlake Terrace began stormwater management activities in the mid-1960s as part of a combined Utility Fund. In 2000, the Utility Fund was divided into separate water, sewer, and stormwater utilities. The Comprehensive Stormwater Plan (Plan) provides guidance for the design, construction, management, and maintenance of the City’s storm system to meet future needs. The Plan provides information about the City’s existing stormwater infrastructure, current operations and maintenance, regulatory requirements, and funding while identifying deficiencies and a recommended course of action to resolve them. It was created in partnership with the 2015 City of Mountlake Terrace Comprehensive Plan and other planning documents adopted by City Council, to ensure a common vision for the future.

MAJOR STORMWATER PROJECTS SINCE THE LAST PLAN Since the last stormwater comprehensive plan in 2008, the City has completed several large stormwater projects, including: •

Hall Creek Culvert Replacement at 230th Street SW (2011). Reduced flooding upstream of undersized culvert.

•

McAleer Creek Culvert Replacements (2014). Replaced undersized culverts along between Lake Ballinger and I-5 to reduce flooding of lakefront property.

•

Lakeview Trail (2015). Decreased stormwater runoff through infiltration through permeable pavement.

City of Mountlake Terrace Comprehensive Stormwater Plan

1-1 November 2018

Gray & Osborne, Inc., Consulting Engineers

•

Town Center Regional Stormwater Facility (2016). Provided stormwater flow control and water quality treatment for Town Center area development.

WHY PLAN NOW? This plan updates the last comprehensive stormwater plan in 2008. The 2018 comprehensive stormwater plan is intended to provide a fresh look into the condition of existing infrastructure and a current evaluation of new stormwater areas of concern. The goal is to help the City be prepared for the future by ensuring that resources are allocated efficiently, and that local, State, and Federal regulations are met.

A 0.85 percent annual growth rate is anticipated through year 2035 in Mountlake Terrace.

Per the City’s 2015 Comprehensive Plan, this growth is expected to bring an increase of 1,538 residents and 3,616 jobs to the community. This plan is intended to help implement the City Council’s overall vision for the City as it grows and changes through time.

WHAT IS STORMWATER MANAGEMENT? Stormwater impacts and management can be influenced by the climate, natural environment, developed environment, and regulatory requirements. In Mountlake Terrace, managing the stormwater system includes: • • • • • • • • • • •

39 inches of rain annually Nine drainage basins 32 miles of stormwater pipe 7 miles of stream Numerous public and private detention and water quality facilities 115 acres of wetland Lake Ballinger (101 acres) NPDES Phase II Municipal Permit Population of 21,090 (anticipated to increase 17% over the next 17 years) $1.8 million Stormwater Operating Budget (proposed 2019-2020 Budget) $1.0 - $1.6 million Stormwater Capital Improvement Budget (proposed 2019-2020 Budget)

Elements of the natural environment listed above are shown in Figure 1-2. In addition, Figure 1-3 shows the drainage basins surrounding the City’s stormwater system which is detailed in Figure 1-4.

1-2 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

LEGEND: Mountlake Terrace

City of Mill Creek

Martha Lake

Bothell Brier Edmonds Kenmore

Puget Sound

Kirkland Lake Forest Park Lynnwood

City of Lynnwood

Mill Creek Seattle Shoreline

Scriber Lake

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CITY OF MOUNTLAKE TERRACE

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COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 1-4 DRAINAGE BASE MAP

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M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\Chapter 2 Maps\Base Map.mxd

Gray & Osborne, Inc., Consulting Engineers

WHAT ARE THE GOALS OF THE STORMWATER PROGRAM? The City strives to provide stormwater service that meets Ecology’s NPDES Phase II Permit requirements, addresses the City’s goals and objectives to maintain existing stormwater infrastructure, and promotes public health, safety, and welfare. These goals include the City Council’s goals to: • • • • • •

Protect and enhance the City’s financial health and stability while maintaining appropriate and essential public services in a cost-effective manner; Generate economic development throughout the community; Implement the downtown “Main Street” revitalization project; Implement the Civil Campus Plan Review, prioritize, and implement capital infrastructure projects to include the development of a strategy to address the City’s aging public facilities; and Develop and implement effective communication and outreach with the community.

Additional goals are: • • • • • • •

Reduce pollutants entering creeks and Lake Ballinger Encourage local involvement in protecting stormwater Minimize soil erosion on construction sites Practice good housekeeping at City facilities and as part of City operations Increase public awareness of pollutant spill prevention/proper cleanup Build capacity to meet more stringent stormwater permit requirements Label all storm drains to discourage dumping of pollutants

Implementation of this Storm Plan will help the City meet its goals related to protecting the financial health related to the stormwater system, addressing aging infrastructure, developing effective public communication, and preserving and protecting surface water resources.

WHAT ARE THE STORMWATER PROBLEMS? Stormwater problems in Mountlake Terrace include: • • • • • •

Increasing hard surface area leading to more polluted runoff Pipes, ponds, and vaults nearing the end their useful life Roots and sediment that clog pipes Unmapped stormwater pipes of unknown structural integrity Undersized conveyance structures Lake Ballinger invasive weeds

City of Mountlake Terrace Comprehensive Stormwater Plan

1-3 November 2018

Gray & Osborne, Inc., Consulting Engineers

WHAT ARE THE RECOMMENDED ACTIONS? To meet these challenges, stormwater programs have been developed to mitigate the impacts of increased runoff, require erosion control measures on construction sites, and improve aquatic habitat. Actions in the plan include rehabilitating aging stormwater infrastructure, increasing the level of service for stormwater facility maintenance, and promoting environmental stewardship.

WHERE DOES THE FUNDING COME FROM? The City’s Stormwater Utility Fund receives revenue from monthly service charges, new connection charges, investment interest, and other sources. These revenues are used to fund operational expenses and capital projects. Additional funding may also come in the form of loans or grants from state or federal programs. Certain expenses are paid from other sources as well, such as joint capital projects that include upgrades to other utility or transportation elements.

1-4 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

CHAPTER 2 KNOWN ISSUES AND SOLUTIONS INTRODUCTION In this chapter, current problems associated with the Mountlake Terrace storm system are described, along with an introduction to potential solutions. Problems are either citywide in nature or are geographically specific.

STORMWATER CONCERNS The Town Center Plan, which is being updated in 2018, is a driving force for economic growth within the City. The Town Center Plan vision is centered on development and redevelopment of a new city center to increase the City’s economic vitality, including changes in land use to higher density developments with more impervious area. Greater impervious area directly increases stormwater runoff, thereby increasing the intensity and total volume of flow.

In addition, older developments may not provide flow control or water quality treatment to current standards if completed before more rigorous stormwater regulations were implemented. Failing infrastructure is also a constant concern, as pipes and other structures approach the end of their lifespan.

Another concern is climate change, which is expected to bring more frequent and intense storms. These larger storm events may result in increased flooding, stormwater runoff and soil erosion.

Potential Solutions The following lists potential action items to address the citywide concerns related to stormwater issues within the City: •

Infrastructure rehabilitation. Using more cost-effective and less disruptive measures such as pipe sliplining to increase pipe service life.

•

Strong Maintenance Program. A rigorous maintenance program to prolong the life of stormwater facilities throughout the City.

•

Implementing Low Impact Development (LID) to mitigate impacts from development and redevelopment.

•

Retrofit Projects: As older developments undergo redevelopment, stormwater flow control and water quality treatment projects are upgraded.

City of Mountlake Terrace Comprehensive Stormwater Plan

2-1 November 2018

Gray & Osborne, Inc., Consulting Engineers

•

Proactive Stormwater Facility Inspections. Regular inspections of public and private stormwater facilities identifies needed maintenance or repair.

FIELD IDENTIFIED PROBLEMS Specific problems in the Mountlake Terrace storm system were identified from staff interviews, site visits, past Capital Improvement Plan project lists (created in 2000, 2008, and 2014), and hydraulic model simulations. With flooding-related concerns the top priority, the projects were then prioritized by City staff based upon the severity of the problem.

High Priority Issues Restoration of Hall Creek north of Lake Ballinger is an important component of the Ballinger Park Master Plan. The Ballinger Park Master Plan is intended to create a “regional destination park,” and is a high priority for the City. Part of the master plan included improvement of the habitat and rehabilitation for the riparian area within the park boundary. Hall Creek is heavily channelized and has lost connectivity to its floodplain. Instream habitat has been simplified, riparian vegetation has been altered from natural conditions, invasive plant species dominate the understory, and there is a lack of side channels for velocity reduction areas to provide aquatic refuge and rearing.

The U.S. Army Corps of Engineers is collaborating with the City on a feasibility analysis for a restoration project which will develop a preferred alternative. The second phase of the project will complete design, engineering, and construction of the proposed creek restoration within the Ballinger Park area. The Hall Creek restoration area is shown in Figure 2-1.

The Cedar Way Dam was constructed in 1985 to provide stormwater detention for a new development in the Lyon Creek basin upstream of the Lake Forest Park boundary. The in-stream storage area has experienced significant vegetation growth and sediment deposition over the years, raising concerns about the future functionality of the detention area and dam. Additionally, the water level behind the dam sometimes reaches close to the top of spillway, and in December 2007, surface water overflowed the emergency spillway. Repeated overflows would compromise the integrity of the earthen dam structure. Figure 2-2 shows the location of the Cedar Way Dam. Another high priority stormwater project for the City involves the new Mountlake Terrace City Hall building which is planned for construction near the current police station located at 232nd Street SW and 59th Avenue West. The expansion of the police building would cover the existing 36-inch stormwater pipe, creating an access and maintenance issue (see Figure 2-3). The project would relocate this existing pipe.

Projects within the vicinity of 56th Avenue West will upgrade key roadway and utility infrastructure in the Main Street area of Mountlake Terrace. Figure 2-4 shows the extent 2-2 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

72N D

PL W

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High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

125

250

500 Feet

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CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-1 ISSUE #1

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Hall Creek Restoration.mxd

237TH PL SW

WAY CEDAR

238TH PL SW

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High Priority Issue #2 Cedar Way Dam Flow Control, Vegetation, and Sediment

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43RD PL W

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High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

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250

500 Feet

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Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-2 ISSUE #2

M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Cedar Way Dam.mxd

230TH ST SW

57TH AVE W

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High Priority Issue #3 Stormwater Pipe Underneath Police Station

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235TH ST SW

236TH ST SW

LEGEND:

Other Priority Issues High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

125

250

500 Feet

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CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-3 ISSUE #3

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Police Station.mxd

56TH AVE W

230TH ST SW

232ND ST SW

58TH AVE W

High Priority Issue #4 Main Street Stormwater Utility Work

235TH ST SW

236TH ST SW

LEGEND:

Other Priority Issue High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

125

250

500 Feet

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CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-4 ISSUE #4

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Main Street.mxd

Gray & Osborne, Inc., Consulting Engineers

of the 56th Avenue West utility projects. Stormwater related work within this area will include realignment or replacement of infrastructure in this vicinity as necessary.

The Hall Creek area north of the Premera Blue Cross complex along 216th Street SW consistently floods during large rainfall events. The Whirlwind Clean and Green business at the northwest corner of 216th Street SW and 68th Avenue West experiences regular flooding because the catch basins in front of the building are lower than the surface water level of Hall Creek; and therefore, water from the stream floods the intersection and near the local business (see Figure 2-5). Sediment buildup within the stream reach also appears to contribute to the flooding seen within this area. In addition, a hydraulic model of this area shows that the two existing 36-inch diameter culverts and one 54-inch diameter culvert under the Premera driveway along the south side of 216th Street SW are undersized for the 25- and 100-year storm event(s). Figure 2-6 shows these areas of concern.

FIGURE 2-5 Flooding of 216th Street and 68th Avenue West during a 2-Year Storm (December 19, 2017) Further upstream to the south, the manhole lid at the intersection of 216th Street SW and 66th Street West is forced upward from hydraulic pressure during high stream flows through the undersized 12-inch diameter pipe. Hydraulic modeling results show both this 12-inch pipe and the 4' x 6' box culvert crossing 66th Avenue West to be undersized during a 25-year and 100-year storm event. A future road reconstruction project is planned for the intersection of 216th Street SW and 66th Street West, providing an City of Mountlake Terrace Comprehensive Stormwater Plan

2-3 November 2018

Gray & Osborne, Inc., Consulting Engineers

opportunity to upgrade the pipe and/or culvert in the near future. However, a hydrologic and hydraulic analysis is needed to understand the downstream impacts of these proposed projects. The location of the pipe and culvert are shown in Figure 2-7.

At the northeast corner of 216th Street SW and 66th Street West is Taylor Pond.

Currently, there is a cooperative agreement between the property owner and the City to maintain this pond. The owner provides landscaping maintenance, while the City is responsible for maintaining pond vegetation and removing sediment. The pond has become overgrown with vegetation and has accumulated a significant amount of sediment, pushing pond rehabilitation beyond routine maintenance. Figure 2-7 shows the location of Taylor Pond.

Issue Classification The problems identified from all sources were compiled and categorized by type and ranked as low, medium, or high priority. The projects were classified due to access (“A”), capacity (“C”), stream (“S”), pond (“P”), or structural (“ST”) related problems.

Figure 2-8 shows the location of these issues, while Table 2-1 gives a general description of the projects.

Projects classified with “access” issues refer to areas of the storm system that are difficult to maintain or replace due to their location. Many of these projects include pipes on private property which could be rerouted to the right-of-way. Over 1.5 miles of pipe were categorized as having access issues.

Projects that are classified as having “capacity” issues include areas where facilities are undersized or are missing conveyance pipes altogether. Undersized pipes were identified from flooding complaints, but require confirmation that the problem is capacity rather than roots or sediment. Adding missing sections of conveyance pipes can be accomplished during road improvement efforts. Approximately 1 mile of capacity problems has been identified throughout the City.

Projects classified as “stream” issues refer to open channels or in-line ponds that require sediment and vegetation removal to restore capacity and water quality treatment functions. These are located along Hall Creek near the city limits to the west and Lyon Creek to the southeast. There is a total of four such areas of concern spanning approximately half a mile within the city limits.

“Pond” projects refer to stormwater flow control and water quality ponds that require sediment and vegetation removal to restore capacity. Only Taylor Pond was identified as needing maintenance above the routine level of service.

“Structural” issues reference areas with deteriorated pipes, and pipes damaged from root intrusion, crushed pipes, dislocated pipes, and other pipe damage. These problems are distributed throughout the City. Approximately 1 mile of pipe has been identified as 2-4 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

68TH AVE W

High Priority Issue #5 Hall Creek at 216th St. SW

Rim elevations of catch basins below creek level during higher storms

Hall Creek 216TH ST SW Premera Driveway X-ing (2) 36" Diameter Culvert w/ (1) 54" Diameter Culvert

Flooding often occurs in this location.

Premera

LEGEND:

High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility Water Body City Limits

0

50

100

200 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-6 ISSUE #5

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Hall Creek Premera 216th.mxd

Ha

ll

e Cr

ek

66TH AVE W

High Priority Issue #7 Taylor Pond Vegetation and Sediment

216TH ST SW

High Priority Issue #6 66th and 216th Undersized 12" Pipe and 4' x 6' Box Culvert

LEGEND:

High Priority Issue Storm Drain Culvert

Stream

Stormwater Facility Water Body City Limits

0

50 100

200 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-7 ISSUE #6 AND #7

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Taylor Pond.mxd

LEGEND:

Hall Lake

Storm Drain

ST7

A9

Cr eek

236TH ST SW

A6 ST20

ST4

C3

C15 ST11

ST10

C17

ST9

Note: See Table 2-1 for descriptions of the issues shown.

0

500

1,000

2,000

3,000 Feet

CITY OF MOUNTLAKE TERRACE S2

56TH AVE W

ST17

We st

WAY

ST6 C2

39TH AVE W

A3

228TH ST SW

A5

C2

C6

(See Table 2-1)

CEDAR

ek

ST2 Issue Number

C11

C13

r Cre

C18

ST18

Lake Ballinger

McAl ee

Structural

ek East

A1

PL W 65TH

ST2

ST1

Lyo n

Stream

Lyon C re

A11

Issue Type

Pond

Lyon Creek

§ ¦ ¨

City Limits

TS W

C10

5

Parcel

Other

S4

C14

C8

4 228TH ST SW

220TH ST SW

44TH AVE W

ST8

Water Body

C4

A10

52ND AVE W

ST 3 A2

A

S1

221 ST S

ST12

C9

244TH ST SW

ST21 48TH AVE W

ST16

A7

C7

c ds n La

Stream

k

Capacity

222ND ST SW

58TH AVE W

Hall Creek 73RD PL W

4

A8

W AVE

228TH ST SW

ST 1

214TH ST SW

e ap

ee Cr

Access

C5

68TH

ST19

226TH PL SW

ST15

220TH ST SW

5 ST

DRIVE LAKEVIEW

76TH AVE W

ST13

C16

66TH AVE W

C1

P1

216TH ST SW S3

61ST PL W

212TH ST SW

COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 2-8 KNOWN ISSUES

M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Known Issues.mxd

³

Gray & Osborne, Inc., Consulting Engineers

structurally deficient, but the area identified likely underestimates the extent of the problem, as only a small amount of the city has been closed circuit television inspected (CCTV-ed). Extensive additional CCTV inspection is needed to determine the full extent of structural deficiencies throughout the City’s stormwater system.

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2-5 November 2018

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TABLE 2-1 Field Identified Problems Issue Number

Issue Type

S1

Stream

S2

Stream

A1

Access

ST1

Structural

Location Hall Creek at Ballinger Lake Park – 23000 Lakeview Drive Cedar Way Dam – 2400 Cedar Way Mountlake Terrace Police Station – 5906 232nd Street SW Main Street - 236th Street SW from I-5 to 56th Avenue West and 56th Avenue West from 236th Street SW to 230th Street SW

56th Ave stormwater improvements to prepare for future development in this area.

Flooding on roadway and at building on NW corner of 216th St. North of Premera – 216th Street SW and 68th Ave. W. as Hall Creek level rises during storms.

SW at 68th Avenue West Currently worst flooding risk area in City.

S3

Stream

C1

Capacity

66th Avenue West and 216th Street SW

P1

Pond

Taylor Pond – 66th Avenue West and 216th Street SW

ST2

Structural

Backyards between 66th and 65th north of 236th

2-6 November 2018

Description U.S. Army Corps of Engineers collaboration. The channelized creek has lost connectivity to its floodplain, instream habitat has been simplified, riparian vegetation has been altered from natural conditions, invasive plant species dominate the understory, and there is a lack of side channels for velocity refuge and rearing.

Overgrown vegetation and sediment accumulation. Risk of dam failure.

The existing 36-inch stormwater pipe underneath the police station interferes with new City Hall construction.

Potential Solution

Priority

Hall Creek Restoration Project

High

Cedar Way Dam Retrofit

High

Reroute

High

Pipe rehabilitation/ replacement

High

Culvert replacement

High

Culvert and pipe replacement Privately owned, cooperative agreement: Owner maintains turf Vegetation and and trees. City removes vegetation and sediment from pond. Pond Sediment has excessive vegetation and sediment.

Removal Slipline or pipe Multiple root and crack issues. Deep pipe. burst Flow backup at intersection of 66th and 216th causing manhole lid to pop up. Road overlay is scheduled for 2021 at 216th and 66th.

City of Mountlake Terrace Comprehensive Stormwater Plan

High

High Med

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TABLE 2-1 – (continued) Field Identified Problems Issue Number

Issue Type

C2

Capacity

C3

Capacity

C4

Capacity

C5

Capacity

ST3

Structural

ST4

Structural

ST5

Structural

C6

Capacity

A2

Access

ST6

Structural

ST7

Structural

ST8

Structural

Location 244th Street SW at 56th Avenue West and Gateway Place 236th Street SW and 49th Place West 44th Avenue West and Hawk Way 52nd Avenue and 221st Street SW 6102 Street Albion Way – 60th Avenue West and I-5 4109 236th Street SW 68th Place West at 225th Street SW 223rd Street SW from 37th Avenue West to 39th Avenue West 224th Street SW and 60th Avenue West 5703 244th Street SW 52nd Avenue West at 219th Street SW 22605 63rd Place West

City of Mountlake Terrace Comprehensive Stormwater Plan

Description

Potential Solution

Priority

Pipe fractured in traffic lane. Shallow near curb.

Slipline

Med

Cracks and fractures at 140 feet.

Slipline

Med

10-foot crack and fracture.

Slipline

Med

Complaints about repetitive flooding at 5103 221st Street SW. CCTV inspection found no blockage or pipe issues. Pipe may be undersized. High groundwater in the area.

Reroute

Med

Cracked pipe.

Replace pipe

Low

Requires more investigation.

Line failing. Area is difficult to access. The system has not been TV inspected.

Residents on the south side of 223rd have significant flows during storm events that are piped to 223rd by sump pumps. Received two complaints in 2007 and 2008.

Storm lines run behind homes on private property, future maintenance poses an issue.

6-inch offset - shallow near curb.

New storm line

Low

Replace pipe

Low

New storm line

Low

Reroute

Low

Replace pipe

Low

Root damage.

Replace pipe

Low

8-inch offset nearly full separation - access is an issue.

Replace pipe

Low

2-7 November 2018

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TABLE 2-1 – (continued) Field Identified Problems Issue Number

Issue Type

ST9

Structural

ST10

Structural

ST11

Structural

ST12

Structural

A3

Access

A4

Access

A5

Access

A6

Access

A7

Access

ST13

Structural

ST14

Structural

ST15

Structural

2-8 November 2018

Location 243rd Place SW at 45th Avenue West 240th Street SW at 46th Place West 53rd Place south of 240th Street East of cul de sac at 58th Place north of 224th 4602 222nd Street SW, 4505 223rd Place SW – 222nd and 223rd Street SW at 46th Street West 227th Street SW east of 66th Avenue West

Potential Solution

Description

Priority

Root intrusion and pipe offsets.

Replace pipe

Low

Cracks/holes in pipe.

Replace pipe

Low

Pipe sag - roots - grade issues.

Replace pipe

Low

Multiple breaks/debris.

Replace pipe

Low

Multiple conflicting lines between 222nd and 223rd, failing pipe on easement between homes. No known capacity issues.

Reroute

Low

Reroute

Low

Slipline or pipe burst

Low

Reroute

Low

Reroute

Low

Tightline

Low

Tightline

Low

Tightline swale

Low

Located on private easement, potential future maintenance issue.

No known capacity or flow issues. Owner wants to build here but can't because of pipe/easement.

Mix of old pipe and open flow drainage. No known capacity or flow issues.

46th Avenue West from 238th Place SW to 243rd Place SW Easement between 54th Avenue West and 55th Avenue West Pipe between 238th and 240th that runs between lots with easement th th from 240 Street SW to 238 access in question. No known flooding problems.

Street SW This system infiltrates right of way runoff onto private property.

22302 65th Avenue West This pipe system has not been CCTV inspected to date. th th From 218 Street SW and 64 Requires more investigation.

Avenue West to the north 219th Place West to the west Requires more investigation.

215th Street SW and 50th Requires more investigation.

Avenue West

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TABLE 2-1 – (continued) Field Identified Problems Issue Number

Issue Type

C7

Capacity

A8

Access

ST16 C8 C9 C10

Structural Capacity Capacity Capacity

A9

Access

A10

Access

ST17

Structural

C11

Capacity

A11

Access

ST18

Structural

C13 C14

Capacity Capacity

C15

Capacity

Location 214th Street SW and 39th Avenue West 222nd Street SW and 67th Avenue West 6703 224th Street SW 22607 63rd Place West 22302 65th Avenue West 58th Avenue West 228th Street SW and 53rd Avenue W 223rd Place SW Backyards between 220th Place SW and 38th Avenue West 3704 225th Place West 23117 63rd Avenue West, 23109 63rd Place West 233rd Street SW between 56th Avenue West and 58th Avenue West 23511 Hedlund Avenue 23010 67th Place West 238th Street SW from 44th Avenue West to 45th Avenue West

City of Mountlake Terrace Comprehensive Stormwater Plan

Description Requires more investigation.

Potential Solution New storm line and manhole

Priority Low

Requires more investigation.

Reroute

Low

Requires more investigation.

Storm line ends at hillside.

Requires more investigation.

Requires more investigation.

Tie in New storm line Tie in New storm line

Low Low Low Low

Requires more investigation.

Reroute

Low

Requires more investigation.

Low

Requires more investigation.

Reroute Slipline or pipe burst New storm line

Pipe is on private property.

Reroute

Low

Failing pipe located on an easement over private property - Town Center Area.

Replace pipe

Low

Tie in two catch basins to existing storm line.

Requires more investigation.

Tie in New storm line

Low Low

Requires more investigation.

New storm line

Low

Requires more investigation.

2-9 November 2018

Low Low

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TABLE 2-1 – (continued) Field Identified Problems Issue Number ST19

Issue Type Structural

C16

Capacity

C17

Capacity

S4

Stream

ST20

Structural

C18

Capacity

ST21

Structural

2-10 November 2018

Location 228th Street SW and 73rd Place 218th Street SW between 66th Avenue West and 64th Avenue West 242nd Street SW between 48th Avenue West and 46th Avenue West

Description Storm lines run behind homes on private property.

Potential Solution Reroute

No conveyance infrastructure.

New storm line

Low

No conveyance infrastructure.

New storm line

Low

237th Place SW at Lyon Creek

Culvert maintenance issue. City currently unplugs the trash rack, located deep in woods.

Culvert replacement

Low

Pipe is at adverse grade.

Replace pipe

Low

No conveyance infrastructure.

New storm line

Low

Cracked pipe.

Slipline

Low

56th Avenue West at 244th Street SW 222nd Street SW between 44th and 39th Avenue West 48th Avenue West south of 220th Street SW

City of Mountlake Terrace Comprehensive Stormwater Plan

Priority Low

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Potential Solutions Depending on the issue type and the amount of detail known, potential solutions to items identified in Table 2-1 range from performing further investigation to construction projects. For access issues on private property within easements, typical solutions include abandoning and rerouting drainage to the right-of-way or performing in-situ rehabilitation such as sliplining (i.e., installing a slightly smaller pipe inside the existing pipe) or pipe bursting (i.e., fracturing the existing deteriorated pipe while pulling a new pipe into place). For capacity issues, installing new, properly-sized conveyance infrastructure is recommended, not sliplining. For non-capacity problems, depending on the material of the pipe and the pipe issue, sliplining may provide greater flow capacity without having to install a new pipe. Stream issues may be solved with culvert replacement, vegetation and sediment removal, or may require further investigation to determine the feasibility of various alternatives. Pond issues can be resolved with vegetation and sediment removal followed by replanting and regular maintenance.

Structural issues will require either replacement of the pipe, in-situ rehabilitation, and/or abandonment.

Some of the potential solutions will require engineering design work, including hydraulic modeling, as well as adding additional tasks into the City’s maintenance schedule to ensure proper operation. A prioritized capital improvement program will help plan for the most critical projects first, and the less critical projects as funding allows. Chapter 4 discusses project prioritization in greater detail.

WATER QUALITY Pollutant Sources In Washington State, water quality standards are established by WAC 173-201A and enforced by the Department of Ecology. The standards are based on two objectives: protection of public health and enjoyment, and protection of fish, shellfish, and wildlife.

For each surface water body in the State, the standards assign specific beneficial uses such as aquatic life, recreation, or water supply. Water quality standards have been developed for each use for parameters such as fecal coliform, dissolved oxygen, temperature, pH, turbidity, and toxic, radioactive, and other harmful substances. The surface water criteria include 29 toxic substances, including ammonia, residual chlorine, several heavy metals, polychlorinated biphenyls (PCBs), and pesticides. A list of typical pollution parameters and their potential impacts on water quality is provided in Table 2-2.

City of Mountlake Terrace Comprehensive Stormwater Plan

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TABLE 2-2 Pollutant Sources and Impacts Pollutant (example)

Sources/Causes

Low Dissolved Oxygen

Increased temperatures, organic wastes.

High pH

Pouring, finishing, and washing cement concrete.

Increased Temperature

Removal of riparian vegetation that provide shade. Erosion of banks widening and making water body shallower.

Reduced solubility of oxygen.

Turbidity

Exposed erodible soils.

Reduced availability of light to plants for photosynthesis.

Nutrients (nitrogen, phosphorous)

Pathogens/Bacteria

Oil and Grease

Organic decomposition of soil erosion, detergents, fertilizers, septic system effluent, livestock manure.

Leaking septic systems or sanitary sewer, pet and livestock waste.

Runoff from roadways, parking lots, and industrial property.

Total Suspended Solids (TSS)

Soil erosion, runoff from paved areas, and scour within a stream.

Heavy Metals

Runoff from roadways, parking areas, and industrial property.

Toxic Organic Compounds (dioxin, dieldrin, polychlorinated biphenyls)

Urban and agricultural runoff, hazardous substance spills, improper disposal of waste products, and industrial discharges.

Organic Material

Yard waste and soil erosion.

2-12 November 2018

Impacts Low oxygen levels put stress on aquatic organisms and can lead to fish kills and reduction in aesthetic values.

Changes in pH affect the toxicity, reactivity, and solubility of many compounds.

Algae blooms causing dissolved oxygen levels to drop.

Waterborne illness.

Hydrocarbon compounds can be toxic to aquatic life at low concentrations.

Inhibit oxygen exchange in gills of aquatic organisms, and may settle out and smother bottom-dwelling organisms.

Changes in pH can increase solubility of accumulated metals making them available for ingestion by fish and insects.

Availability of toxic organic compounds to aquatic life is difficult to determine because of their adsorption to particulate matter.

Decreased dissolved oxygen concentrations.

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Total Maximum Daily Loads Program The 303(d) Program, issued by the Environmental Protection Agency (EPA) and administered by Ecology, is a program that assists with listing and prioritizing impaired waters for the purpose of developing Total Maximum Daily Loads (TMDLs). A TMDL establishes the maximum amount of a pollutant allowed in a waterbody and, if exceeded, provides a framework for how water quality within that particular waterbody will be restored. Each waterbody is given a category; Category 1 meets tested standards, Category 2 is a water of concern, Category 3 is insufficient data, Category 4 is a polluted water that does not require a TMDL, and Category 5 is a polluted water that requires a TMDL. In the City of Mountlake Terrace, Lake Ballinger is a Category 5 waterbody for dioxin, dieldrin, polychlorinated biphenyls, and bacteria; a Category 4A water for total phosphorous; and a Category 2 waterbody for 2, 3, 7, 8-TCDD TEQ (a type of dioxin).

Hall Creek is a Category 5 waterbody for bacteria. Both McAleer Creek and Lyon Creek are a Category 5 waterbody for bacteria, dissolved oxygen, temperature, and bioassessment (evaluation of the condition of a waterbody based on the organisms living within it). Lyon Creek is also a Category 5 waterbody for mercury. At the northeast corner of the City, Scriber Creek is considered a Category 5 waterbody for bioassessment and fecal coliform.

As noted, Category 5 waters are polluted water bodies that require a TMDL or other water quality improvement project. Lake Ballinger was issued a TMDL for total phosphorus in 1993, and was shown to meet the phosphorous level goals specified in the TMDL in 2005. Scriber Creek is tributary to Swamp Creek, which has also been issued a TMDL for fecal coliform.

Lake Ballinger is used for swimming and other recreational activities. With such a large portion of Mountlake Terrace draining to Lake Ballinger and all of Mountlake Terrace draining to Lake Washington, it is especially important to reduce pollutants in runoff to preserve the health and recreation uses of these waters. This is most effectively done at the source before pollutants accumulate and are carried downstream to harm other bodies of water.

Lake Ballinger Awareness of Lake Ballinger water quality issues first began in the early 1970s. In 1972, Ecology performed a study of 34 lakes in the Puget Sound area, including Lake Ballinger.

Of the 34 lakes studied, Lake Ballinger was found to have the poorest water quality. This initiated a series of reports in the following years, identifying ongoing nutrient issues.

The first Lake Ballinger Restoration Project began in 1980 with the help of a grant from Ecology and the EPA. Several projects to improve water quality followed in the 1980s and 1990s. In 1993, Ecology issued Lake Ballinger’s first TMDL for phosphorus. The City of Mountlake Terrace Comprehensive Stormwater Plan

2-13 November 2018

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first meeting between Mountlake Terrace and Edmonds city staff and the Lake Ballinger Community Association to discuss Lake Ballinger issues occurred in 2005, and again in 2007 with all six local jurisdictions (Mountlake Terrace, Edmonds, Shoreline, Lynnwood, Lake Forest Park, and Snohomish County) in the Lake Ballinger/McAleer Creek Watershed. A Strategic Action Plan was developed and approved in 2009. One year later, a Capital Improvement Program was approved based on the Strategic Action Plan.

By 2014, both phases of the McAleer Culvert Replacement Project were completed.

Recommended actions to improve water quality noted in the 2014 Lake Ballinger State of the Lake Report included habitat improvements along Hall Creek north of the lake, water quality structures at outfalls to Hall Creek, continued efforts to control sediment and pollutants in runoff, and contribution to Ecology-managed regional efforts.

Potential Solutions Continued education efforts on ways the community can help reduce pollutants, as well as inspections of public and private facilities, will aid in protecting the quality of surface waters in Mountlake Terrace. As part of the updated NPDES Phase II Permit to be released in 2019, it is anticipated that source control inspections at local businesses and comprehensive watershed planning will be required. This will address water quality related issues at the origin of the problem. Additionally, retrofits, where available, will further improve the effectiveness of the City’s storm system to improve water quality.

Potential solutions to water quality related issues are listed in Table 2-3, and specific structural related water quality measures that may be constructed as retrofit projects are described in Table 2-4. Finally, TMDL and other water quality improvement efforts should be continued to ensure compliance with regulatory requirements.

TABLE 2-3 Potential Solutions for Pollutant Sources Pollutant Low Dissolved Oxygen High pH

Increased Temperature

2-14 November 2018

Potential Solution • Increased stream buffers.

• Riparian restoration.

• Business source control inspections.

• Implementation of pH control measures on construction sites • Increased stream buffers.

• Riparian restoration.

• Education of property owners about restoring vegetation along streams.

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TABLE 2-3 – (continued) Potential Solutions for Pollutant Sources Pollutant

Turbidity

Nutrients (nitrogen, phosphorous)

Pathogens/Bacteria

Oil and Grease

Total Suspended Solids (TSS)

Heavy Metals

City of Mountlake Terrace Comprehensive Stormwater Plan

Potential Solution • Installation of structural control measures such as detention ponds and emerging technologies such as filters to help settle out sediment that carries pollutants (see Table 2-3).

• City inspections and enforcement during construction projects.

• Education of property owners to reduce use of fertilizers.

• Conduct DNA testing to determine the source of bacteria in receiving waters, then customize remedial action.

• Provide pet waste stations at City parks.

• Provide education to citizens on the importance of disposing of pet waste properly.

• Conduct business source control inspections and provide education/enforcement on appropriate controls to aid in preventing spills.

• City-wide program such as a “Don’t Drip and Drive” campaign to educate citizens on repairing leaking cars.

• Install structural controls such as oil/water separators (see Table 2-3).

• Install structural controls such as detention ponds and emerging technologies including water quality filters to help settle out pollutant-laden sediment (see Table 2-3).

• Conduct business source control inspections and provide education/enforcement on appropriate BMPs to aid in preventing metals mixing with runoff.

• Provide general education on preventing metals through such items as general car maintenance (i.e., brake pads).

• City street sweeping program.

• Structural controls (see Table 2-3).

2-15 November 2018

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TABLE 2-3 – (continued) Potential Solutions for Pollutant Sources Pollutant

Toxic Organic Compounds (dioxin, dieldrin, polychlorinated biphenyls)

Organic Material

2-16 November 2018

Potential Solution • Conduct business source control inspections, provide education or enforcement on appropriate measures to prevent metals from mixing with runoff.

• Provide general education on preventing spills and not dumping waste into catch basins.

• Label stormwater catch basins (“No dumping”) • Structural controls (see Table 2-3).

• Education of private property owners and landscaping companies on proper disposal locations for yard waste.

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TABLE 2-4 Potential Structural Related Water Quality Tools Facility Biofiltration Swale Filter Strip Bioretention Facility

Wet Pools

Media Filtration

Oil/Water Separators Regional Treatment Facilities

Description

Benefits Thick vegetation provides soil A shallow ditch, mild side stabilization, stormwater treatment, slopes, and thick vegetation and nutrient uptake.

A strip of vegetated land Easy maintenance, provides basic for sheet flow level of treatment.

Vegetation provides soil A shallow depression with stabilization, nutrient uptake, and deep rooted vegetation aesthetics. Engineered soil mix increases treatment and filtration.

Stormwater treatment through A wet pond, wet tank/vault, gravity settling and biological or wetland that maintains a uptake of algae and permanent pool of water microorganisms.

Pond or vault with High level of treatment. High engineered sand/soil mix or level of maintenance is typically Ecology approved media needed. filtration devices.

Can be a hooded catch Retain oil from travelling basin insert or coalescing downstream. Require regular plate separator maintenance for proper operation.

Large containment area for high volumes of runoff, Provide high levels of treatment to typically incorporating large basins. Regular maintenance detention and biofiltration is required. or media filtration

City of Mountlake Terrace Comprehensive Stormwater Plan

2-17 November 2018

CHAPTER 3 STORMWATER MANAGEMENT PROGRAM EVALUATION AND RECOMMENDATION INTRODUCTION This chapter provides the evaluation of the stormwater management program with the recommended level of service for operation and maintenance activities and National Pollutant Discharge Elimination System (NPDES) Phase II Permit requirements.

POTENTIAL NEW STORMWATER POLICY AND/OR CODE As the stormwater program grows, new situations for which there is no existing city policy and or code occur. Some examples where code/policy changes may be required: •

Ditch conversion to covered culverts by property owners

•

Adjustment to monthly stormwater charges when single-family homeowners greatly increase hard surfaces

•

Streamlined fines or cost recovery for progressive enforcement of water quality violations and source control of pollutants

•

Adoption of the 2019 Ecology Surface Water Manual for Western Washington

OPERATION AND MAINTENANCE The objective of a stormwater maintenance program is to assure the continued function of stormwater management facilities for a healthier hydrologic environment. A complete maintenance program includes more than the physical tasks of cleaning catch basins, pipes, and open ditches; maintenance of vegetation in biological treatment structures; and proper disposal of debris from the maintenance activities. Maintenance programs also involve completing and maintaining a facilities inventory and base map, scheduling inspections and maintenance activities, assessing costs for contract maintenance versus staff maintenance, and record keeping for Ecology audits. The City’s current equipment and staffing capabilities cannot meet the level of service recommended in this Plan. A dedicated stormwater utility CCTV system, for example, is required for the City to achieve the initial planned schedule of television inspections of the entire piped system within the next 7 years. A new Stormwater Technician is also necessary to achieve the required staffing hours for operation and maintenance activities. Table 3-1 shows the recommended operation and maintenance program along with the new and existing City of Mountlake Terrace Comprehensive Stormwater Plan

3-1 November 2018

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staffing components. A description of these activities follows the table. As identified in Table 3-1, the program currently contains three full-time staff; however, per the recommended level of service, the program will need an estimated 5.8 staff members.

3-2 November 2018

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TABLE 3-1 City of Mountlake Terrace Recommended Operation and Maintenance Program Total Units Maintenance Activity Description in System Units Period Operations and Maintenance/Preventive Maintenance (PM) Catch basin/manhole Catch Basins, 2,286 Biennial inspection - Public EA Catch basin/manhole Catch Basins, 762 Biennial cleaning - Public EA Detention Systems 49 Systems, EA Annual Cleaning - public Detention Systems 24 Systems, EA Annual Repair - public Water quality treatment Treatment facility cleaning 10 4 Years facility, EA public Critical drainage: Every other 24 Locations, EA May-Oct month Critical drainage: 24 Locations, EA 3 x monthly Nov-April Moderate-low priority 56 Locations, EA 1 x 6 month drainage: May-Oct Moderate-low priority Every other 56 Locations, EA drainage: Nov-April month Creek maintenance: Spot Creek 1 Annual May-Oct Locations, EA Creek maintenance: Spot Creek 1 Annual Nov-April Locations, EA

Frequency (Times/Yr)

Time/Unit (Hours)

No. of Personnel

Time/Year (Hours)

0.5

0.25

1

286

0.5

0.50

2

381

1

4

2

390

1

3

2

146

0.25

4

2

20

Media filter and vortex systems.

3

0.5

2

72

Dry season maintenance

18

0.75

2

648

1

0.5

2

56

3

0.5

2

168

1

80

3

240

6

16

2

192

Storm Line Jetting

3,262

Pipe segments, EA

Once every 7 years

0.15

1

2

979

CCTV pipe condition assessment

3,262

Pipe segments, EA

Once every 7 years

0.15

1.5

2

1,468

City of Mountlake Terrace Comprehensive Stormwater Plan

Comments Inspection of 50 percent of entire system annually Cleaning of 1/3 of 50 percent of entire system annually Public systems only, including flow control Public systems only, including flow control

Wet season maintenance, includes post-storm inspection Dry season maintenance inspection and cleaning Wet season maintenance inspection and cleaning Removing blockages, debris, and beaver dams Removing blockages, debris, and beaver dams Jetting in advance of CCTV, 7 years is catch up, eventually 10 years CCTV evaluation, 7 years initially; eventually every 10 years 3-3 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 3-1 – (continued) City of Mountlake Terrace Recommended Operation and Maintenance Program Total Units in System

Units

Maintenance Period

Frequency (Times/Yr)

Time/Unit (Hours)

No. of Personnel

Time/Year (Hours)

Municipal facility upkeep

1

Facility, EA

Monthly

12

8

2

192

Catch basin minor repairs

1

City-wide representation of CBs

As needed

1

80

2.5

200

Stormwater facility maintenance

6

Storm Facilities, EA

As needed

1

8

2

96

Fixing pipe blockages

1

As needed

10

8

2

160

Street sweeping

1

Monthly

9

119

1

1,071

Pond and swale sediment removal

1

Annual

1

80

3

240

As needed

4

40

3

480

Annual

6

80

1

480

Dry months

Activity Description

Pipe Repairs/Installation Easement Maintenance - Mowing Easement Backyard Basin Inspection and Maintenance Utility Locator

1 1

Pipe, EA Section for Street Sweeping Represents 1/3 ponds in City City-wide spot repairs City-wide mowing areas

9 months of full time sweeping for one staff Assumes light cleaning at 1/3 sites per year, more thorough cleaning of one pond or swale per year Repair and/or installation pipe by staff

1

City-wide backyard areas

Annual

1

80

1

80

Dry months

1

~10% of all utility locates in the City

Daily

261

0.8

1

209

Approximately 10% of utility locator time

Annual

1

2

1

130

Public systems only

Stormwater Technician (New Position) Stormwater facility Flow Control 65 inspection - public Facility, EA

3-4 November 2018

Comments For inspection, monitoring, and housekeeping, Operations Center and decant facility Raising grates to grade & repairing broken catch basins, incl. traffic control (.5) For facilities that require minor maintenance/repair - update based on additional inspection scope.

Roots, sediment, debris, etc.

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 3-1 – (continued) City of Mountlake Terrace Recommended Operation and Maintenance Program Activity Description Stormwater facility inspection - private Business stormwater source control inspections

Total Units in System 75

Units Flow Control Facility, EA

Maintenance Period

Frequency (Times/Yr)

Time/Unit (Hours)

No. of Personnel

Time/Year (Hours)

Annual

1

3.5

1

263

Private systems only

Annual

0.2

3

1

240

Will be required in new stormwater permit in 2019

400

Businesses, EA

O&M Procedures to meet permit requirements

1

O&M Procedures

Monthly

12

8

1

96

GIS to support stormwater permit requirements

1

GIS technician

Monthly

12

10

1

120

IDDE investigation and problem resolution

1

City-wide IDDE incidents

As needed

8

5

1

40

Comments

Implemented practices, policies and procedures to reduce stormwater impacts runoff from public land and road maintenance activities Includes 40 hours for facility mapping; 50 hours developing new GIS data management for NPDES permit reporting, 30 hours additional required for 2019 permit Assuming an average of 8 IDDE events/year Locating outfalls, water quality testing, sample delivery, and documentation of all stormwater outfalls during the dry season View and interpret CCTV footage, document, issue work orders and follow-up (2 days/month)

IDDE outfall screening and testing

15

Outfalls

Annual

1

3

1

45

CCTV review and prioritization

1

Monthly CCTV Review

Monthly

12

40

1

480

1

Education Activities

Annual

12

8

1

96

Fulfills City’s stormwater permit requirements

1

Employee

Weekly

52

8

1

416

Assumes 8 hours per week on storm only

Public outreach/involvement stewardship activities Administration Admin Assistant

City of Mountlake Terrace Comprehensive Stormwater Plan

3-5 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 3-1 – (continued) City of Mountlake Terrace Recommended Operation and Maintenance Program Total Units in System

Units

Maintenance Period

Frequency (Times/Yr)

Time/Unit (Hours)

No. of Personnel

Time/Year (Hours)

PW Director

1

Employee

Monthly

12

12.5

1

150

PW Supervisor

1

Employee

Daily

12

84

1

1,008

Activity Description

Stormwater Program 1 Employee Annual 12 1 1 Manager Operations Manager 1 Employee Weekly 52 3 1 Total Hours Required Total Admin Hours required Total Technical Hours required Total Full-Time Administrative Staff Required (based on 1,480 hours per year per person) Total Technical Staff Required (based on 1,480 hours per year per person) Total Full-Time Operations and Maintenance Staff Hours Required Total Full-Time Operations and Maintenance Staff Required (based on 1,428 hours per year per person) Current Full-Time Storm Operations and Maintenance Staff Current Full-Time Storm Operations and Maintenance Staff Deficit

3-6 November 2018

Comments Based on 10% of time as per 2017 budget Based on 68 percent of available time dedicated to storm

1,480

Dedicated to storm 100 percent

156 12,973 3,210 1,510 2.2 1.0 8,253 5.8 4.0 -1.8

Budgeting, planning

City of Mountlake Terrace Comprehensive Stormwater Plan

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Maintenance Standards Volume 5 of the Department of Ecology’s Stormwater Management Manual for Western Washington identifies maintenance standards for flow control, conveyance, and water quality facilities that are required to be established by the City to meet NPDES Program requirements.

The following is a brief description of the recommended maintenance procedures and the impact on stormwater pollution and flow control that could result from not maintaining a facility.

Street Sweeping Streets with concrete curb and gutter or thickened asphalt edges are part of the stormwater conveyance system. All streets accumulate particles, silt, leaves, debris, and other pollutants that will collect in the stormwater conveyance system if not removed.

Street sweeping (not washing) is an important maintenance item to reduce pollutants from entering receiving waters and to reduce the potential for blocking of the conveyance system. The City owns and operates its own street sweeper and currently sweeps arterial streets nine times per year and collector and residential streets four to five times per year.

Approximately 800 lane miles are swept each year.

Catch Basin Cleaning The City has mapped over 2,200 public storm drainage catch basin and inlet structures.

Catch basin sumps are important features that allow deposition of particulate matter carried in the stormwater. When sumps become filled to 60 percent of their volume, the efficiency of pollutant removal diminishes significantly, and maintenance is recommended. The City is currently required to inspect catch basins once every 2 years.

Catch basins are typically cleaned with a vactor truck that removes the sediment from the sump. This sediment must be disposed of properly at an appropriate disposal site due to the presence of heavy metals.

Pipe Cleaning The City has over 51 miles of stormwater pipe mapped. Pipes in the City vary in size from 4-inch to 144-inch diameter. Pipe types include concrete, corrugated metal, ductile iron (DI), high density polyethylene (HDPE), and polyvinyl chloride (PVC). Although there are no specific guidelines, a desired schedule for pipe cleaning is to clean storm pipes on a 3- to 5-year rotating basis. The primary maintenance activity for stormwater pipes is removal of accumulated sediment once the accumulated sediment or debris exceeds 20 percent of the diameter of the pipe. Sediment can decrease conveyance capacity or can be washed out of the pipes during storm events causing downstream sediment and pollution problems. When jetting and flushing pipes, adequate downstream siltation control must be in place. This is usually accomplished by using a vactor truck at City of Mountlake Terrace Comprehensive Stormwater Plan

3-7 November 2018

Gray & Osborne, Inc., Consulting Engineers

the nearest downstream structure to remove any water mixed with sediment. The City does not currently own a television inspection system dedicated to the stormwater utility.

A television inspection program that inspects 10 percent of the system per year is recommended.

Open Ditch Mowing and Cleaning The City currently has mapped over 7 miles of open drainage channels. Grass-lined ditches and swales provide biofiltration if vegetation is allowed to remain within the channel and along the side walls. The primary pollutant removal mechanism of a bioswale (or ditch) involves filtration by grass blades, which enhance sedimentation, as well as trapping and adhesion of pollutants to the grass and thatch. These pollutants then enter the soil where they decompose or can be broken down by bacteria within healthy soil. To be most effective, the vegetation within the ditch should be cut down to a height between 3 and 4 inches. The City currently mows each ditch approximately five times per year. Mowing is the first method that should be used to reduce capacity loss. If the ditch must be reshaped to promote drainage or remove excess materials, the work should be performed during dry weather. Two methods to clear obstructions or reshape the ditch include the following: 1.

Swales can be cleaned with a backhoe, taking care not to remove more material than is necessary. Clean areas only where there is a flow restriction. Small amounts of sediment should be removed by hand.

2.

Under the close supervision of City staff, yearly maintenance may be performed by a qualified contractor. A contractor can utilize an auger or other equipment to place material from the swale/ditch directly into a dump truck.

Stormwater Detention Facility Cleaning There are 54 City maintained and approximately 120 privately maintained stormwater facilities located within the City. Of the 54 public stormwater facilities, nine are detention ponds. Upon installation and conveyance to the City by a private developer, the City requires a manual regarding specific maintenance requirements for facilities such as stormwater ponds. At a minimum, these facilities should be monitored annually for sediment accumulation and structure failures (i.e., cracked vault walls, gaps at manhole covers, etc.). Providing inspection of both City-owned and privately-owned facilities on an annual basis is a requirement of the NPDES Phase II Permit. Removal of accumulated sediment is anticipated to be required once every 3 years, or when accumulated sediment takes up more than 10 percent of the facility depth. Failure to maintain ponds has the potential to cause facility flooding and may prevent the facility from performing adequate water quality treatment.

3-8 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

Culverts Culverts should be inspected annually. For certain culverts historically known to flood, inspection is required after every significant runoff event to check for blockages, excessive scour, and deposition of new sediment and debris. Especially in the wet season, any potential blockage should be immediately removed. For culverts serving waters of the state, this type of maintenance activity will require a Hydraulic Project Approval (HPA) from the Washington Department of Fish & Wildlife (WDFW). The HPA is usually valid for 5 years. In emergency situations, immediate work is allowed with proper notification to WDFW and an HPA issued after-the-fact.

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) The National Pollutant Discharge Elimination System (NPDES) is a Federal program that regulates stormwater and wastewater discharges to waters of the state. For certain activities, including discharge of municipal separate stormwater systems, a permit is required. While it is a Federal permit, the regulatory authority is delegated to the Washington State Department of Ecology (Ecology). In response, Ecology developed and issued the Western Washington Phase II Municipal Stormwater Permit. The Permit was issued by Ecology on January 17, 2007, and was modified in 2009 and 2012. A new permit was issued August 1, 2013, and was intended to be in effect until July 31, 2018.

Ecology announced that they will extend this permit an additional year to August 2019 to allow them time to prepare a new 5-year permit. The new permit will likely require source control inspections of businesses and comprehensive watershed planning.

Permit Requirements The current NPDES Phase II Permit includes the following topics: • • • • • • • •

Stormwater Management Program Plan Public Education and Outreach Public Involvement and Participation Illicit Discharge Detection and Elimination Controlling Runoff from New Development, Redevelopment, and Construction Sites Municipal Operations and Maintenance Monitoring and Assessment Reporting Requirements

Each of these topics are presented in greater detail below. Ecology staff have indicated these topics will be similar in the updated permit scheduled to be issued in 2019. The following paragraphs discuss each of these items.

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Stormwater Management Program Plan A Stormwater Management Program (SWMP) Plan is a document created by the City as overall guidance on how the City will address required elements of the NPDES Phase II Permit in the year ahead. The SWMP must be updated annually for submittal to Ecology no later than March 31 of each year. The City’s current SWMP Plan was prepared in March 2018 and is available on the City’s website.

Draft language of the proposed 2019 NPDES Phase II Permit includes a provision for cities to provide a “Comprehensive Stormwater Planning Program.” As part of this program, cities may have to provide a report on how stormwater management needs are influencing city policies. This report would also have to describe water quality and watershed protection policies, strategies, codes and other measures that are intended to protect and improve local receiving water health. In addition, the permit discusses the need for the City to participate in stormwater management action planning which involves assessment and prioritization of receiving waters within the City. For at least one high priority receiving water, the City would then prepare a Stormwater Management Action Plan (SMAP) which would discuss stormwater management actions for this basin, the need for stormwater facility retrofits, an implementation schedule and budget, as well as short-term (i.e., 6-year) and long-term (i.e., 20-year) actions.

Public Education and Outreach/Public Involvement and Participation An important element of a stormwater management plan is public education and outreach. The involvement of the public is necessary to insure the overall success of the stormwater management program. To be motivated to improve water quality, people must first be aware of existing stormwater and surface water problems, their potential role in creating and resolving these problems, and what actions they can take to avoid causing harm.

Issues of local relevance need to be identified and programs designed to address them specifically. Resources for education materials about these topics include: •

The Washington Stormwater Center: http://www.wastormwatercenter.org/coordination

•

EPA’s NPS Outreach Toolbox: https://cfpub.epa.gov/npstbx/index.html

•

Puget Sound Starts Here Library: http://pugetsoundstorm.weebly.com/library.html and http://www.psp.wa.gov/econet_PSSH.php#2

The draft NPDES 2019 Phase II language allows communities to participate in education via a regional program such as the “Don’t Drip and Drive” campaign produced by the local STORM group, a coalition of local jurisdictions who share resources to provide 3-10 November 2018

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regional education on stormwater issues. Similar to the current stormwater permit, the draft permit language suggests providing another evaluation of the effectiveness of the stormwater education program by 2020. The results of this evaluation shall be used to follow social marketing practices to develop a program evaluation plan that is tailored to the community. This plan must be implemented by 2021 and then re-evaluated in 2024.

Illicit Discharge Detection and Elimination The illicit discharge detection and elimination (IDDE) component of the permit includes mapping the City’s stormwater system, ensuring the City’s ordinances prohibit illicit discharges, and providing a program that includes IDDE training, IDDE inspections and an available hotline for citizens to call should they see an illicit discharge. At least 12 percent of the City’s area needs to be inspected for IDDE purposes on an annual basis.

Ecology has also indicated that source control inspections for businesses, including spill prevention, will be added to the new 2019 Permit. Source control inspections will count toward the 12 percent annual IDDE field screening requirement.

Staff Training The City must develop and implement an ongoing training program for City employees whose construction and maintenance tasks may impact stormwater quality. This program addresses the importance of protecting water quality, O&M standards, inspection procedures, BMP selection, preventing impacts to water quality, and procedures for reporting water quality concerns.

The City should ensure that the staff is well-trained on techniques and procedures to inspect and maintain best management stormwater practices as outlined in the NPDES Phase II Permit requirements. At a minimum, staff should be educated on how to maintain catch basins, detention ponds and control structures, bioswales/ditches, and any other best management practices implemented within the City. Staff should also be knowledgeable in identifying pollutant sources and in understanding pollutant control measures, spill response procedures, and environmentally acceptable material handling practices. Ecology’s website provides numerous resources to assist with this. There are also a number of IDDE training videos available on the internet. Renewal training for all employees on a biennial basis is recommended as well.

Personnel should also be up-to-date on erosion and sediment control issues so they can properly investigate and advise contractors regarding problem areas during construction.

Appropriate staff members attend Certified Erosion and Sediment Control Lead (CESCL) certification courses. This certification is renewed every 3 years.

Controlling Runoff from New Development, Redevelopment and Construction Sites Elements of the development related portion of the Phase II Permit include adopting Ecology’s 2014 stormwater manual (which the City has done), having a process to City of Mountlake Terrace Comprehensive Stormwater Plan

3-11 November 2018

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perform plan review and inspections of development activities, and ensuring operations and maintenance of private facilities is addressed during the development process. This requirement also includes annual inspections and enforcement of maintenance for private flow control and water quality facilities.

Municipal Operations and Maintenance As discussed earlier, the City is required to have an O&M program including maintenance standards, staff training, annual inspections of flow control and water quality facilities, 2-year inspections of all catch basins and business source control inspections. Table 3-1 lists the City’s planned O&M efforts necessary to meet the Phase II Permit.

Business Source Control Inspections Per the draft 2019 Permit language, the business source control inspections will include providing a program to inspect public and private commercial and industrial businesses such as restaurants, grocery stores, and auto repair shops to ensure that appropriate stormwater best management practices are being implemented per an ordinance adopted by the City (due in 2022). If during the inspections, City personnel find that the BMPs are not being implemented per the ordinance, staff will educate the business’ employees on how to address business appropriate, operational source control techniques. Should the operational BMPs be unsuccessful in preventing illicit discharges, then structural source control BMPs may be required. By 2022, the City will need to create an inventory of businesses to be inspected. By 2023, the City must conduct inspections for 20 percent of the businesses on the inventory list on an annual basis. As seen in Table 3-1, the City plans to utilize 240 staff hours per year toward these inspections.

Monitoring and Assessment Each year the City provides funds to a regional program overseen by Ecology. This program is intended to monitor the status and trends of water quality related to Puget Sound, to determine the effectiveness of various BMPs practiced throughout the Puget Sound Basin, and to implement the Source Identification Information Repository (SIDIR) for the region. The permit will list the exact amount the City owes, based upon the population of the City.

Reporting Requirements Each year by March 31st, the City shall submit an annual report to Ecology that summarizes the City’s efforts in meeting permit requirements during the previous year.

Once completed, this report is posted on the City website.

3-12 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

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Recommended NPDES Permit Program To meet the requirements of the upcoming NPDES Phase II Permit, an estimate was made regarding the hours City staff would dedicate toward each of the non-maintenance related items of the Phase II Permit (See Table 3-2). All maintenance related activities are covered in Table 3-1.

City of Mountlake Terrace Comprehensive Stormwater Plan

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TABLE 3-2 Recommended NPDES Phase II Permit Program Hours (Non-Maintenance) Permit Task Public Education and Outreach/Public Involvement and Participation

Hours/Year 144

IDDE Response

72

Stormwater Related Plan Review

240

Municipal Housekeeping

72

Project Management

600

Inspection of Public/Private Stormwater Systems Annual NPDES Phase II Report and Stormwater Management Plan (SWMP) Total Hours Required Total Full-Time Staff (FTE) Required

360

3-14 November 2018

40

Description 12 hours per month for public meetings, educating citizens/students, posting education material 6 hours per month to respond to spills and conduct source investigations 20 hours per month to review stormwater related plans for incoming development 6 hours per month to coordinate with Public Works crews and conduct training 50 hours per month to manage stormwater related projects 20 hours per month to inspect public/private systems.

40 hours per year to obtain updated information for the report and revise the previous year’s SWMP.

1,528 1.0

City of Mountlake Terrace Comprehensive Stormwater Plan

CHAPTER 4 IMPLEMENTATION PLAN INTRODUCTION The City of Mountlake Terrace’s Stormwater Implementation Plan consists of a Capital Improvement Plan (CIP), guidelines to fund the CIP projects, and programmatic needs associated with the Stormwater Utility. The recommended projects include structural elements to address stream, access, capacity and pond related issues.

The CIP was developed primarily based upon City staff input who identified current storm drainage problems as well as outstanding projects documented in previous years.

Whenever an inadequately sized culvert, pipe, or channel is replaced or repaired, the improvement may transfer the problem downstream by allowing more flow through a previously restricted point. For instance, this is particularly true in the Hall Creek area, where the most severe flooding occurs. Flooding risk can be decreased by greater understanding of where flows will be directed during major storms if upstream improvements are made. Building a sufficiently detailed hydrologic and hydraulic model is recommended.

Large stormwater capital improvement projects not now identified as part of this Plan may be needed in the future. Smaller unforeseen CIP projects can be addressed by the spot drainage program, but larger projects will quickly exceed the program’s limited budget. These projects may be necessary for emergencies, to address growth, to meet other city goals such as the Ballinger Park Master Plan, or to address water quality problems. Due to budgetary constraints, the construction of these other projects may drive changes in the proposed completion date for current CIP projects. As new information becomes available, the plan can be adapted to reschedule, add, or delete proposed projects, and to expand or reduce the scope of the projects. As the proposed project date approaches, each capital improvement project will be re-evaluated by staff and approved by City Council. In this way, the plan remains responsive to both longterm and short-term needs.

CAPITAL IMPROVEMENT PLAN The following recommended 6-Year Capital Improvement Plan includes nine capital improvement projects as prioritized by City staff. The recommended CIP projects scheduled for completion within the next 6 years are described below. These projects are shown in Figure 4-1 and are summarized by year in Table 4-1. Specific detailed project related cost estimates are found in Appendix A. Each project cost estimate includes an additional 20 percent construction contingency, 20 percent for engineering design services, 15 percent for permitting, 17 percent for construction administration, and a City of Mountlake Terrace Comprehensive Stormwater Plan

4-1 November 2018

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10.3 percent sales tax. All project costs are based on 2018 dollars with a 4.0 percent annual adjustment made for inflation in future years. Where noted, certain projects have simplified cost estimates as insufficient information exists at this time to complete a detailed cost estimate. The naming convention for the projects described below uses the initials of the type of project (i.e., stream, capacity, etc.), along with an identification number.

Some of the projects listed may require lengthy coordination with permitting agencies.

Permit acquisition will be incorporated as part of the project’s overall schedule.

6-YEAR CIP PROJECTS Below, projects are categorized by their type in the list of CIP projects anticipated for the next 6 years.

STREAM S1: Ballinger Park/Hall Creek Analysis and Improvement Projects Problem: Hall Creek in Ballinger Park is biologically limited, constrained by increased channelization of Hall Creek and loss of latitudinal connectivity between the creek and its floodplain. There is a lack of side channels for velocity refuge and rearing of Coho salmon and other stream biota. A handful of invasive plant species are dominant around the streams and wetland areas, crowding out a more diverse native plant community that could thrive there.

Opportunity: The project is part of the fulfillment of the 2015 Ballinger Park Master Plan goals for the habitat restoration of Hall Creek. It would create habitat in an already urbanized and rapidly developing urban area, particularly for species of concern such as amphibians, and would also provide significant habitat for migrating birds. Watershedlevel objectives for habitat improvement would also be met through the project. In order to fulfill this component of the Ballinger Park Master Plan in a cost-effective manner, the City approached the Corps of Engineers as a project partner under the Section 206 Continuing Authorities Program. In the summer of 2018, the Corps determined that the project met federal interests by improving the quality of the environment and having a positive impact on significant ecosystem resources. The U.S. Army Corps of Engineers is currently collaborating with the City of Mountlake Terrace, to complete a feasibility study and develop a preferred alternative. If the project moves forward after the feasibility study, the next phase will design, complete engineering, and then construct a restoration project. The cost estimates provided represent the City’s estimated share in funds to complete the analysis and related projects. Figure 4-2 shows the area in detail.

Feasibility Study Estimated Project Cost

(2018): $227,000 (2019): $113,000 Design and Engineering Estimated Project Cost (2021): $175,000 4-2 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

212TH ST SW

61ST PL W

CIP C1

CIP S1: Ballinger Park/Hall Creek k (2018), $113,000 (2019) Cost: $227,000 ree $1,750,000 (2022) $175,000C(2021),

pe a c CIP ds S2: Hall Creek Hydrologic and Hydraulic nAnalayis a L Cost: $200,000 (2020)

214TH ST SW

216TH ST SW

CIP S3: Hall Creek Flood Abatement Project Cost: $500,000 (2024) CIP A1: Police Station 36" Pipe Replacement Cost: $400,000 (2019)

52ND AVE W

220TH ST SW

CIP P2: Cedar Way Dam Pond Rehabilitation Cost: $470,000 (2023) CIP ST1: 56th Ave. W. Area Pipe Replacements Cost: $300,000 (2019), $1,000,000 (2022)

§ ¦ ¨ 5

228TH ST SW

58TH AVE W

DRIVE LAKEVIEW

Lyo n

Cr eek

228TH ST SW

We st

LEGEND: Storm Drain

CIP A1

CIP S1

PL W 65TH

Lyon C re

CIP ST1

236TH ST SW

ek

56TH AVE W

r Cre

WAY

CIP P2

McAl ee

Parcel 0

500

1,000

2,000 Feet

³

CITY OF MOUNTLAKE TERRACE CEDAR

Lake Ballinger

City Limits

ek East

W AVE

228TH ST SW

68TH

226TH PL SW

CIP P1: Taylor Pond Rehabilitation Cost: $295,000 (2021)

TS W

44TH AVE W

73RD PL W

222ND ST SW

220TH ST SW

48TH AVE W

Hall Creek

221 ST S

CIP C1: 66th Ave. W. 42" Pipe Replacement Cost: $566,000 (2020)

39TH AVE W

CIP S2 / S3

66TH AVE W

CIP P1

COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-1 6-YEAR CIP LOCATIONS

M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-1 CIP locations.mxd

72N D

PL W

228TH ST SW

230 TH S

TS

CIP S1: Ballinger Park / Hall Creek Analysis and Projects Phase I (2018-2019) includes a hydraulic analysis where Phase II (2021-2022) includes floodplain / habitat restoration projects Cost: $227,000 (2018), $113,000 (2019) $175,000 (2021), $1,750,000 (2022)

W

VI KE LA EW .

R D

BALLINGER LAKE PARK

Lake Ballinger

LEGEND:

CIP Area

Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

125

250

500 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-2 BALLINGER PARK / HALL CREEK (CIP S1)

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-2 Hall Creek Restoration.mxd

Gray & Osborne, Inc., Consulting Engineers

Estimated Construction Cost Total Estimated Cost

(2022): $1.05M to $1.75M $1.57M to $2.27M

S2: Hall Creek Hydrologic and Hydraulic Analysis Problem: Preliminary modeling shows culverts in the Hall Creek area are undersized, but there is insufficient information available to gauge the impact of the removal of upstream flow restrictions on downstream flood-prone properties. Making upstream changes without this understanding may increase the risk of flooding downstream.

Solution: A full hydraulic and hydrologic analysis of Hall Creek (Figure 4-3) will allow the City to make informed decisions on how to effectively address flooding in the Hall Creek area. The analysis will include review of flows, culvert capacity issues, and the impact of sediment load transport within the system.

Estimated Project Cost (2019): $200,000 S3: Hall Creek Flood Abatement Project Problem: Properties along Hall Creek are vulnerable to flooding.

Solution: Based upon the results of the Hall Creek Hydrologic and Hydraulic Analysis (CIP S2), resulting projects may include structural related improvements that are anticipated to include box culvert replacements and/or sediment removal measures (Figure 4-3). For planning purposes, $500,000 will be budgeted for construction of these projects until such time that the analysis is finalized and the exact improvement projects and their associated costs are known.

Estimated Project Cost (2024): $500,000 (placeholder until final costs are known) ACCESS A1: Police Station Stormwater Pipe Replacement Problem: An existing 36-inch stormwater pipe is installed partially underneath the City police station. The future expansion of the police station as part of the City Hall project will cover more of this large, critical pipe within the building footprint. Construction could compromise pipe integrity. Additionally, being located under the building will make for expensive pipe repairs in the future.

City of Mountlake Terrace Comprehensive Stormwater Plan

4-3 November 2018

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Solution: Reroute the pipe as shown in Figure 4-4. Construction will be handled as part of the City Hall construction contract, but the project will be paid for separately with stormwater utility funds.

Estimated Project Cost (2019): $400,000 STRUCTURAL ST1: 56th Avenue West Area Stormwater Replacement Projects Problem: Significant future infrastructure work is anticipated for the 56th Avenue West area shown in Figure 4-5. The age and condition of the stormwater pipe in this area may require numerous relocation, repair, and replacement projects.

Solution: Each stormwater pipe will be replaced in-kind with similar diameter pipe. The cost below is estimated as complete realignment, repair, and/or replacement costs are currently unknown.

Estimated Project Cost (2019): $300,000 (2022): $1,000,000 CAPACITY C1: 66th Avenue West Pipe Replacement Problem: In larger storms, an undersized 12-inch stormwater pipe backs up stormwater flow at the intersection of 66th Avenue West and 216th Street SW, causing a manhole lid in the intersection to lift and create a hazard for drivers.

Solution: Replace the undersized culvert with a new 42-inch CPEP pipe during a planned upgrade of 66th Avenue West. Upgrading the stormwater pipe while the road surface is exposed will reduce overall cost, and the upsized pipe will provide greater capacity for upstream runoff (see Figure 4-6). Allowing additional water downstream would impact the culvert under 66th Avenue West. The Hall Creek Hydraulic Analysis (CIP S2) will analyze the downstream and upstream impact of this change.

Estimated Project Cost (2020): $566,000 POND P1: Taylor Pond Rehabilitation Problem: Taylor Pond (located at the corner of 66th Avenue West and 216th Street SW) was constructed in 1980 as a regional detention and water quality facility to fulfill a condition of the construction and development for the Plat of Taylor Industrial Park.

4-4 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

61ST PL W

CIP S2: Hall Creek Hydrologic and Hydraulic Analysis Analysis of Hall Creek flooding in the vicinity of 216th St. and 66th Ave. W. Cost: $200,000 (2020) CIP S3: Hall Creek Flood Abatement Project Resulting project from analysis (possibly culvert replacement / sediment diversion) Cost: $500,000 (Placeholder for projects beginning in 2024)

Premera

73RD PL W

220TH ST SW

228TH ST SW

DRIVE LAKEVIEW

§ ¦ ¨ 5

Hall Creek

76TH AVE W

5

W AVE

228TH ST SW

§ ¦ ¨

68TH

226TH PL SW

Storm Drain Culvert

Stream

CIP Area

Stormwater Facility City Limits

Water Body

0

375

750

1,500 Feet

³

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

PL W 65TH

LEGEND:

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-3 HALL CREEK HYDROLOGIC AND HYDRAULIC ANALYSIS AND PROJECTS (CIP S2/S3)

M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-4 North Hall Creek.mxd

232ND ST SW

60TH AVE W CIP A1: Police Station Stormwater Replacement Reroute a 36-inch stormwater pipe currently located underneath the police station Cost: $400,000

VETERANS MEMORIAL PARK

LEGEND:

CIP Area

Storm Drain Culvert

Stream

Stormwater Facility Water Body City Limits

0

50

100

200 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-4 POLICE STATION STORMWATER REPLACEMENT (CIP A1)

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-5 Police Station.mxd

56TH AVE W

230TH ST SW

232ND ST SW

58TH AVE W

CIP ST1: 56th Ave. W. Pipe Replacement Anticipated numerous stormwater replacement/realignment projects estimated to be 12-inch diameter Cost: $300,000 (2019) $1,000,000 (2022)

235TH ST SW

236TH ST SW

LEGEND: Storm Drain Culvert

Stream

CIP Area

Stormwater Facility City Limits

Water Body

0

125

250

500 Feet

³

CITY OF MOUNTLAKE TERRACE

COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-5 56TH AVE. W. STORMWATER REPLACEMENT PROJECTS (CIP ST1)

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-6 56th projects.mxd

Ha

ek

66TH AVE W

CIP C1: 66th Ave. W. Pipe Replacement Replace existing 12-inch diameter storm pipe with a 42-inch diameter pipe Cost: $566,000

ll

e Cr

216TH ST SW

LEGEND: Storm Drain Culvert

Stream

CIP Area

Stormwater Facility City Limits

Water Body

0

50 100

200 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-6 66TH AVE. W. PIPE REPLACEMENT (CIP C1)

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-7 66th Ave.mxd

Gray & Osborne, Inc., Consulting Engineers

The original design included a pond and outlet structure to detain stormwater runoff during storm events. In 1988 the pond inlet area was reconfigured to include a serpentine flow path through the addition of rock berms installed perpendicular to the original water flow within the pond. Vegetation was planted to allow for enhanced water quality through uptake of nutrient into the plant material.

However, this pond often gets clogged with excessive sediment and invasive vegetation, reducing the capacity of the pond to store stormwater and improve water quality.

Solution: Rehabilitate Taylor Pond (Figure 4-7) by removing accumulated sediment and excessive vegetation, replant native vegetation, and replace quarry spalls as necessary to return the pond to a fully functioning condition.

Estimated Project Cost (2021): $295,000 P2: Cedar Way Dam Pond Rehabilitation Problem: The instream pond upstream of the Cedar Way Dam has accumulated significant sediment over time. This has reduced the pond storage capacity and partially obstructed the pond outflow. Pond maintenance access is poor, due to steep slopes and vegetation which obstruct the maintenance access road. Since sediment will naturally continue to accumulate in the pond over time, the addition of an easily-accessible sediment removal area will reduce long-term maintenance costs and time required.

Proposed solution: The Cedar Way Dam rehabilitation project includes excavating and removing an estimated 150 cubic yards of sediment from the in-stream pond, providing a rehabilitated quarry spall maintenance access road and constructing a sediment diversion area (see Figure 4-8). Further analysis is needed regarding the appropriate size of the sediment diversion area. This project is anticipated to include extensive permitting issues and should be coordinated with participating permit agencies early in the design phase.

Estimated Project Cost (2023): $470,000 RATE STUDY R1: Stormwater Rate Study Problem: Current stormwater rates are insufficient to meet the need to replace aging stormwater infrastructure and meet Ecology’s stormwater permit requirements for the future.

City of Mountlake Terrace Comprehensive Stormwater Plan

4-5 November 2018

Gray & Osborne, Inc., Consulting Engineers

Solution: Provide a detailed financial analysis with the intention of adjusting stormwater monthly rates and connection fees necessary to adequately fund the level of service needed for the stormwater utility today and into the future.

Estimated Project Cost (2019): $60,000 ANNUAL INFRASTRUCTURE REPLACEMENT AN1: Spot Repair Program For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Estimated Annual Cost (2019-2020): $200,000 (increases 5 percent annually beginning in 2021) AN2: Road-Related Upgrade Program Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects. This is a cost-effective way to upgrade stormwater pipes and minimize disruption to traffic.

Estimated Annual Cost (2019-2020): $100,000 (increases 3 percent annually beginning in 2022) AN3: Aging Infrastructure Replacement Program As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

Estimated Annual Cost (2019-2020): $300,000 (increases 3 percent annually beginning in 2025)

4-6 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

Ha

ek

66TH AVE W

CIP P1: Taylor Pond Rehabilitation Remove excessive vegetation/sediment and replace vegetation where appropriate Cost: $295,000

ll

e Cr

216TH ST SW

LEGEND: Storm Drain Culvert

Stream

CIP Area

Stormwater Facility City Limits

Water Body

0

50 100

200 Feet

³

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-7 TAYLOR POND REHABILITATION (CIP P1)

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-8 Taylor Pond.mxd

237TH PL SW

WAY CEDAR

238TH PL SW

Lyon Creek

CIP P2: Cedar Way Dam Rehabilitation Excavate ~150 cy of sediment, rehabilitate quarry spall access road, construct a sediment diversion area Cost: $470,000

242 ND ST SW

43RD PL W

44TH AVE W

CED AR C T

LEGEND:

CIP Area

Storm Drain Culvert

Stream

Stormwater Facility City Limits

0

125

250

500 Feet

³

Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE FIGURE 4-8 CEDAR WAY DAM POND REHABILITATION (CIP P2)

M:\Mountlake Terrace\17507 Storm Comp Plan\GIS\CIP\Fig 4-3 Cedar Way Dam.mxd

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-1 6-Year Capital Improvement Plan Projects Project No.

Year

R1

2019

Project Name Stormwater Rate Study

Project Description Analysis of rate scenarios to plan for maintaining a desired level of service for the stormwater utility.

Cost(1) $60,000

S1 (Phase I)

2019

Ballinger Park/Hall Creek Feasibility Study

Analysis of Lower Hall Creek/Ballinger Park for habitat/floodplain restoration efforts

$227,000(2) (2018) $113,000(2) (2019)

A1

2019

Police Station Stormwater Pipe Replacement

Reroute a 36-inch stormwater pipe currently located underneath the police station

$400,000

Anticipated numerous stormwater replacement/realignment projects

$300,000

th

56 Avenue West Area Stormwater Replacement Projects

ST1

2019

AN1

Annually

Spot Repair Program

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

S2 2019 Total Project Cost for 2019: C1 2020

Hall Creek Hydrologic and Hydraulic Analysis 66th Avenue West Pipe Replacement

AN1

Annually

Spot Repair Program

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

Total Project Cost for 2020:

City of Mountlake Terrace Comprehensive Stormwater Plan

For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

Analysis of Hall Creek flooding Replace existing 12-inch diameter storm pipe with 42-inch diameter For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

$200,000 $100,000 $300,000 $200,000 $1,900,000 $566,000 $200,000 $200,000 $300,000 $1,266,000

4-7 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-1 – (continued) 6-Year Capital Improvement Plan Projects Project No. S1 (Phase II)

Year 2021

Ballinger Park/Hall Creek Analysis (Phase II)

P1

2021

Taylor Pond Rehabilitation

AN1

Annually

Spot Repair Program

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

Total Project Cost for 2021: S1 2022 (Phase II)

Project Name

Ballinger Park/Hall Creek Analysis (Phase II) 56th Avenue West Area Stormwater Replacement Projects

ST1

2022

AN1

Annually

Spot Repair Program

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

Project Description Floodplain/Habitat restoration projects for Lower Hall Creek/Ballinger Park Rehabilitate Taylor Pond by removing excessive vegetation/sediment and replace vegetation where appropriate For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

Floodplain/Habitat restoration projects for Lower Hall Creek/Ballinger Park Anticipated numerous stormwater replacement/realignment projects estimated to be 12-inch diameter For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

Total Project Cost for 2022: P2

2023

AN1

Annually

4-8 November 2018

Cost(1) $175,000(2) $295,000 $210,000 $105,000 $500,000 $1,110,000 $1,005,000 to $1,750,000(2) $1,000,000 $220,500 $110,250 $1,100,000 $4,180,750

Cedar Way Dam Pond Rehabilitation Spot Repair Program

Excavate ~150 cy of sediment, rehabilitate quarry spall access road, construct a sediment diversion area For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

$470,000 $231,525

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-1 – (continued) 6-Year Capital Improvement Plan Projects Project No.

Year

Project Name

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

Project Description Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

Total Project Cost for 2023:

Cost(1) $115,763 $1,100,000 $1,917,288

S3

2024

Hall Creek Flood Abatement Project

AN1

Annually

Spot Repair Program

AN2

Annually

Road Related Upgrade Program

AN3

Annually

Aging Infrastructure Replacement Program

These projects are the result of the Hall Creek Hydrologic and Hydraulic Analysis which may include culvert replacement and/or sediment diversion structures.

For repair or replacement of small-scale failing pipe or stormwater infrastructure where repairs were unforeseen and the need is immediate.

Allows for repair, replacement, or relocation of stormwater pipes as required when pipes are exposed for road improvement projects.

As the City’s stormwater pipes reach the end of their service life, this program funds pipe replacement with the goal of being able to replace 2 percent of the entire system per year.

$500,000(3)

$243,100 $121,550 $1,600,000

Total Project Cost for 2024: $2,464,650 Total 6-Year CIP Cost: $12,838,688 (1) Costs shown represent today’s dollars escalated 4.0 percent annually to the year of anticipated construction.

(2) Costs shown represent the City of Mountlake Terrace’s portion of estimated funds to complete the Ballinger Park/Hall Creek study and projects associated with the Army Corps of Engineers’ feasibility study.

(3) The costs are presently unknown until project specifics are determined. A placeholder of $500,000 in 2024 has been selected as a starting point to budget for these projects beginning in 2024.

City of Mountlake Terrace Surface Water Comprehensive Plan

4-9 November 2018

Gray & Osborne, Inc., Consulting Engineers

20-YEAR CIP PROJECTS In addition to the 6-year CIP projects, lower priority projects will be addressed as part of the ageing infrastructure replacement program over the next 20 years. These projects are based off of currently known problems or from observations that were historically documented. In some cases, additional investigation using closed circuit television inspection (CCTV) is needed to determine the severity of the problem. Specific costs were not determined for each project. Table 4-2 lists estimated pipe replacement costs per lineal feet based upon open-trench methods or other pipe rehabilitation methods such as cured-in-place pipe, sliplining, or pipe bursting. These costs represent 2018 dollars. Any future estimates determined from the dollar amounts in Table 4-2 should be escalated by approximately 4 percent per year to account for inflation.

TABLE 4-2 Pipe Replacement Costs per Linear Foot Pipe Diameter 12-inch 18-inch 24-inch 36-inch 42-inch 48-inch 12-Inch 12-Inch 12-Inch (1)

Without Road With Road Restoration Restoration Open-Trench Method $153 $330 $170 $350 $225 $400 $260 $440 $300 $490 $355 $540 (1) Pipe Bursting $230 -(1) Sliplining $230 -(1) Cured-in-Place Pipe (CIPP) $170 --

Cost includes traffic control, trench excavation safety system, and pit excavation/restoration.

Table 4-3 lists the 20-year CIP projects which were also shown previously in Figure 2-8.

The projects listed within Table 4-3 serve as a resource for City staff to complete stormwater improvement projects as part of road improvements and/or as replacement opportunities occur.

4-10 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-3 20-Year Capital Improvement Projects(1) CIP Number

Issue Type

Location

S4

Stream

237th Place SW at Lyon Creek

ST2

Structural

ST3

Structural

ST4

Structural

ST5

Structural

ST6

Structural

ST7

Structural

ST8

Structural

ST9

Structural

ST10

Structural

ST11

Structural

ST12

Structural

ST13

Structural

ST14

Structural

ST15

Structural

ST16

Structural

Backyards between 66th Avenue and 65th Avenue north of 236th Street 6102 Street Albion Way 60th Avenue West and I-5 4109 236th Street SW 68th Place West at 225th Street SW 5703 244th Street SW 52nd Avenue West at 219th Street SW 22605 63rd Place West 243rd Place SW at 45th Avenue West 240th Street SW at 46th Place West 53rd Place south of 240th Street East of cul de sac at 58th Place north of 224th From 218th Street SW and 64th Avenue West to the north 219th Place West to the west 215th Street SW and 50th Avenue West 6703 224th Street SW

City of Mountlake Terrace Comprehensive Stormwater Plan

Problem Description High maintenance trash rack which requires unplugging, located deep in woods.

Potential Solution Culvert replacement

Priority Low

Slipline or pipe burst

Med

Replace pipe

Low

New storm line

Low

Replace pipe

Low

Replace/reroute pipe

Low

Root damage.

Replace pipe

Low

8-inch offset, nearly full separation - access is an issue.

Replace pipe

Low

Intrusion and pipe offsets.

Replace pipe

Low

Cracks/holes in pipe.

Replace pipe

Low

Pipe sag - roots - grade issues.

Replace pipe

Low

Multiple breaks/debris.

Replace pipe

Low

Requires more investigation.

Tightline

Low

Requires more investigation.

Tightline

Low

Requires more investigation.

Tightline swale

Low

Requires more investigation.

Tie-in

Low

Multiple root and crack issues, deep pipe.

Cracked pipe.

Requires more investigation.

Line failing. Area is difficult to access. The system has not been CCTV inspected.

6-inch offset - shallow near curb. Homeowner at 6406 227th Street. SW wants to build over the easement.

4-11 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-3 – (continued) 20-Year Capital Improvement Projects CIP Number

Issue Type

ST17

Structural

ST18

Structural

ST19

Structural

ST20

Structural

ST21

Structural

C2

Capacity

C3

Capacity

C4

Capacity

Location Backyards between 220th Place SW and 38th Avenue West 233rd Street SW between 56th Avenue West and 58th Avenue West 228th Street SW and 73rd Place 56th Avenue West at 244th Street SW 48th Avenue West south of 220th Street SW 244th Street SW at 56th Avenue West and Gateway Place 236th Street SW and 49th Place West 44th Avenue West and Hawk Way

Capacity

52nd Avenue and 221st Street SW

C6

Capacity

223rd Street SW from 37th Avenue West to 39th Avenue West

C7

Capacity

C8 C9 C10

Capacity Capacity Capacity

C5

4-12 November 2018

214th Street SW and 39th Avenue West 22607 63rd Place West 22302 65th Avenue West 58th Avenue West

Potential Solution Slipline or pipe burst

Problem Description Requires more investigation.

Failing pipe located on an easement over private property - Town Center Area.

Priority Low

Replace pipe

Low

Reroute

Low

Replace pipe

Low

Cracked pipe.

Slipline

Low

Pipe fractured in traffic lane. Shallow near curb.

Slipline

Med

Cracks and fractures at 140 feet.

Slipline

Med

10-foot crack and fracture.

Slipline

Med

Reroute

Med

New storm line

Low

Storm lines run behind homes on private property.

Pipe is at adverse grade.

Complaints about repetitive flooding at 5103 221st Street SW. CCTV inspection found no blockage or pipe issues. Pipe may be undersized. High groundwater in the area.

Residents on the south side of 223rd have significant flows during storm events that are piped to 223rd by sump pumps. Received two complaints in 2007 and 2008. At least one resident may have routed storm to the sanitary sewer.

Requires more investigation.

Storm line ends at hillside Requires more investigation.

Requires more investigation.

New storm line and manhole New storm line Tie-in New storm line City of Mountlake Terrace Comprehensive Stormwater Plan

Low Low Low Low

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-3 – (continued) 20-Year Capital Improvement Projects CIP Number C11 C13 C14

Issue Type Capacity Capacity Capacity

C15

Capacity

C16

Capacity

C17

Capacity

C18

Capacity

A2

Access

A3

Access

A4

Access

Location 3704 225th Place West 23511 Hedlund Avenue 23010 67th Place West 238th Street SW from 44th Avenue West to 45th Avenue West 218th Street SW between 66th Avenue West and 64th Avenue West 242nd Street SW between 48th Avenue West and 46th Avenue West 222nd Street SW between 44th and 39th Avenue West 224th Street SW and 60th Avenue West 4602 222nd Street SW, 4505 223rd Place SW 222nd and 223rd Street SW at 46th Street West

Problem Description Requires more investigation.

Tie-in two catch basins to existing storm line.

Requires more investigation.

Potential Solution New storm line Tie-in New storm line

Priority Low Low Low

Requires more investigation.

New storm line

Low

No conveyance infrastructure.

New storm line

Low

No conveyance infrastructure.

New storm line

Low

No conveyance infrastructure.

New storm line

Low

Storm lines run behind homes on private property, future maintenance poses an issue.

Reroute

Low

Multiple conflicting lines between 222nd and 223rd, failing pipe on easement between homes. No known capacity issues.

Reroute

Low

227th Street SW east of 66th Avenue West

Located on private easement, potential future maintenance issue.

No known capacity or flow issues. Owner wants to build here but can't because of pipe/easement.

Reroute

Low

City of Mountlake Terrace Comprehensive Stormwater Plan

4-13 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-3 – (continued) 20-Year Capital Improvement Projects CIP Number

Issue Type

A5

Access

A6

Access

A7

Access

A8

Access

A9

Access

A10

Access

A11

Access (1)

Location 46th Avenue West from 238th Place SW to 243rd Place SW Easement between 54th Avenue West and 55th Avenue West from 240th Street SW to 238th Street SW 22302 65th Avenue West 222nd Street SW and 67th Avenue West 228th Street SW and 53rd Avenue West 223rd Place SW 23117 63rd Avenue West., 23109 63rd Place West

Potential Solution

Problem Description Mix of old pipe and open flow drainage. Requires more investigation.

Slipline or pipe burst

Low

Pipe between 238th and 240th that runs between lots with easement access in question. Requires more investigation.

Reroute

Low

This system infiltrates right of way runoff onto private property.

This pipe system has not been CCTV inspected to date.

Reroute

Low

Requires more investigation.

Reroute

Low

Requires more investigation.

Reroute

Low

Requires more investigation.

Reroute

Low

Requires more investigation.

Reroute

Low

See Figure 2-8 for project locations.

4-14 November 2018

Priority

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

FINANCIAL PLAN The financial resources available to the City to fund the operation and maintenance and capital improvements include service charges, connection charges, grants and loans. This chapter also provides a summary of additional potential funding sources.

The City has formed a stormwater utility to fund ongoing operation and maintenance, and capital improvements. A 6-year and 20-year budget forecast and rate recommendation required to fund the planned stormwater program for this utility are provided.

Capital project expenditures are estimated to range from $1.1 million to $4.2 million per year within the 6-year planning period as shown in Table 4-1. In addition, the estimated annual expenditures for the stormwater utility operations, not including capital projects, is $2.6 million in 2019. The City’s current stormwater-related revenues are inadequate to support the planned operational expenses and capital improvements over the proposed 6-year and 20-year planning period.

CURRENT CHARGES AND CONNECTIONS The City of Mountlake Terrace stormwater utility formation and rate structure is codified in Mountlake Terrace Municipal Code Chapter 13.05.340 and 13.05.350. The current stormwater service charges are shown in Table 4-4 below and are billed on a bimonthly schedule. One Equivalent Residential Unit (ERU) corresponds to 2,282 square feet of impervious surface area for non-single-family properties per MTMC 13.05.350. Each single-family lot is charged a monthly rate of one ERU, regardless of lot size or amount of impervious surface on the lot. For non-single-family residential parcels, the monthly stormwater service charge is $11.45 for every 2,282 square feet of impervious surface area per parcel multiplied by a contribution factor, which is based on the percentage of impervious surface coverage of the lot. The City currently charges a capital improvement fee of $245 per single-family home, and $245 per newly constructed ERU for multifamily or commercial lots. The total number of ERUs in the City will be used to determine the monthly service charge required to support the O&M program and planned capital improvements. Based on billing records, the City currently has 13,638 ERUs. TABLE 4-4 Stormwater Utility Monthly Billing Charges Parcel Type Single-Family Residential Non-Single Family Residential (1) (2)

No. ERUs 1 1 per 2,282 SF impervious surface

Monthly Rate(1) $11.45 $11.45 x No. of ERUs x Contribution Factor(2)

Customers are billed bi-monthly; For financial analysis purposes, the monthly rate is shown.

The contribution factor is determined by amount of impervious surface coverage on the lot (1% 20% = 0.5, 21% - 40% = 1.0, 41% - 70% = 1.50, Over 70% = 2.0.

City of Mountlake Terrace Comprehensive Stormwater Plan

4-15 November 2018

Gray & Osborne, Inc., Consulting Engineers

Per MTMC 13.05.360.B.4, the City allows a reduction in the stormwater rate for nonsingle-family residential properties that are served by a retention, detention, or water quality facility under the following conditions: •

Properties with private detention and storm water quality systems are eligible for a 25 percent reduction in the total storm water service charge if they: o

o •

Are owned, operated and maintained by the property owner in accordance with the ordinances of the City of Mountlake Terrace and the City of Mountlake Terrace storm water utility operation and maintenance standards; and Meet the City design standards current at the time of the most recent development or redevelopment of the parcel.

Properties with private detention and water quality systems are eligible for a 50 percent reduction in the total storm water service charge if they: o

o

Are owned, operated and maintained by the property owner in accordance with the ordinances of the City of Mountlake Terrace and the City of Mountlake Terrace storm water utility operation and maintenance standards; and Meet the most current City design standards.

The bimonthly service charge is levied by the City upon all developed property within the City’s boundary. The stormwater service charge funds operations, improvements, and maintenance to address drainage problems within the City. The funding also allows the City to legally operate and maintain a storm drainage system and comply with regulations regarding the collection, storage, treatment, and discharge of stormwater runoff into the natural environment.

SERVICE CHARGE DETERMINATION The 6-year financial analysis assumes the capital improvement projects from Table 4-1 are funded from bi-monthly service rates, connection charges and bond revenue. As an alternative, low interest loans or grants may be used when necessary as described later in this chapter. Use of low interest loans may be financially favorable to self-financing as long as the interest costs of the loans are less than the interest that can be earned from reserve funds.

The budget forecast assumptions for this Plan are included in Table 4-5. The stormwater utility expenses were taken from the 2019-2020 budget.

4-16 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-5 Financial Forecast Assumptions Item Number of ERUs in 2019 Growth (Single-Family and Non-Single-Family) Labor Costs Inflation Wage Benefits Inflation General Costs Inflation Construction Costs Inflation Investment Interest Annual Spot Storm Repair Increase Annual Overlay Related Storm Upgrade Increase Annual Infrastructure Replacement Program Increase (1)

Assumption 13,638 0.6%(1) 2.25% 4.0% 2.0% 4.0% 1.5% 5.0% 3.0% 3.0%

A growth rate of 0.37 percent in 2019 and 0.6 percent for each year thereafter was utilized so as to match assumptions provided in other City planning documents.

In addition to the items listed above, the following are included for financial forecasting purposes: •

Connection charges would increase at the same rate as the monthly service charge. Currently, the connection fee is $245. This is expected to rise to $1,020 by the end of the 6-year planning period based on the financial assumptions of the Plan.

•

The beginning fund balance is estimated to be $1,286,578 at the start of 2019.

•

Existing debt service will be retired in 2030, 2032 and 2034.

•

In 2020, the Stormwater Utility will fund the purchase of a new vactor truck to be utilized solely by Stormwater.

•

Three additional Full Time Equivalent (FTE) positions (as described in Chapter 3) will be added to provide the desired level of service for maintaining stormwater infrastructure. New positions were added halfway through 2019.

City of Mountlake Terrace Comprehensive Stormwater Plan

4-17 November 2018

Gray & Osborne, Inc., Consulting Engineers

PRELIMINARY RATE ANALYSIS Tables 4-6 and 4-7 present a simple, cash-based rate analysis based on the recommended project financing. Table 4-6 shows the 10-year financial analysis (2019 – 2028) whereas Table 4-7 shows the remainder of the 20-year financial analysis (2029 – 2038). The financial analyses are provided for preliminary planning purposes. A stormwater rate study will be completed in 2019 which will evaluate adjusting rates to meet the desired level of service in the Plan.

Based on the assumed capital improvement project completion dates, the stormwater service charge and connection charge should increase to accommodate the proposed 6-year Capital Improvement Plan. RCW 35.92.025, which authorizes cities and towns to charge for connecting to their system, requires that the charge be an equitable share of the cost of the existing system. The current City connection charges shown are likely below the maximum limit allowed by law.

The maximum connection charge allowed is calculated by dividing the cost of the existing utility assets by the number of existing customers or ERUs. The upcoming rate study will consider establishing an allowable ceiling to raise the connection charge. The ceiling is established from the value of the existing system and the cost of future projects.

There are no specific capital projects listed beyond the 6-year horizon however, the City intends to annually allocate between $600,000 and $3.0 million toward replacing existing infrastructure via the various annual pipe replacement funds discussed earlier. These budget amounts may be adjusted further in the City’s upcoming stormwater rate study.

4-18 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-6 10-Year Financial Forecast Analysis (2019-2028) Line No. Revenue 2019 REVENUES AND OTHER SOURCES: BEGINNING FUND 1 $1,286,578 BALANCES OPERATING REVENUES ERUs (Billable as 2 13,638 factored) ERU Monthly Service 3 $11.45 Rate Stormwater Rate 4 $1,808,381 Revenues Connection Charge 5 Revenue (New ERUs x $12,250 Con. Charge) Connection Charge $245 6 Investment Interest $54,237 7 Other Revenues $13,600 8 Total Operating Revenue $1,888,468 EXPENSES OPERATING EXPENDITURES 9 Debt Service $733,091 Stormwater Maintenance 10 $1,535,029 (Non-street sweeping) 11 Regulatory Compliance $254,571 12 Street Sweeping $131,437 TOTAL OPERATING 13 $2,654,128 EXPENDITURES Operating Revenues over (under) Operating 14 ($765,660) Expenditures OTHER FINANCING SOURCES Intergovernmental 15 $15,000 (i.e., Grants)

City of Mountlake Terrace Comprehensive Stormwater Plan

2020

2021

2022

2023

2024

2025

2026

2027

2028

($694,970)

$1,603,972

$710,918

$2,402,860

$1,489,872

$2,045,335

$1,708,638

$3,204,072

$3,265,801

13,688

13,770

13,853

13,936

14,020

14,104

14,189

14,274

14,360

$17.18

$20.61

$23.70

$26.55

$29.20

$31.54

$33.43

$35.43

$36.85

$2,821,097

$3,405,596

$3,940,043

$4,439,287

$4,912,650

$5,337,450

$5,691,794

$6,069,445

$6,350,253

$30,000

$59,040

$68,724

$76,971

$85,688

$92,543

$99,264

$105,219

$110,715

$600 $54,237 $13,600 $2,918,934

$720 $24,060 $13,600 $3,502,296

$828 $10,664 $13,600 $4,033,030

$927 $36,043 $13,600 $4,565,901

$1,020 $22,348 $13,600 $5,034,286

$1,102 $30,680 $13,600 $5,474,273

$1,168 $25,630 $13,600 $5,830,287

$1,238 $48,061 $13,600 $6,236,325

$1,287 $48,987 $13,600 $6,523,556

$733,091

$1,013,091

$1,013,091

$1,363,091

$1,363,091

$1,475,091

$1,475,091

$1,587,091

$1,587,091

$2,094,355

$1,548,932

$1,584,769

$1,621,498

$1,659,143

$1,697,730

$1,737,283

$1,777,831

$1,819,400

$264,712 $133,601

$271,316 $136,699

$278,099 $139,873

$285,066 $143,126

$292,222 $146,461

$299,572 $149,879

$307,123 $153,382

$314,880 $156,973

$322,850 $160,655

$3,225,759

$2,970,038

$3,015,833

$3,412,782

$3,460,917

$3,622,272

$3,672,879

$3,836,775

$3,889,996

($306,825)

$532,258

$1,017,197

$1,153,119

$1,573,369

$1,852,002

$2,157,408

$2,399,550

$2,633,560

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$35,000

$25,000

4-19 November 2018

$25,000

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-6 – (continued) 10-Year Financial Forecast Analysis (2019-2028) Line No. 16

Revenue Revenue Bond Proceeds Total Other Financing 17 Sources TOTAL REVS & 18 OTHER SOURCES CAPITAL EXPENDITURES: Engineering Admin.

19 Charge (Operating & Construction) Other Professional Services Telemetry System 20 Controls 21 Stormwater Rate Study Ballinger Park/Hall 22 Creek Feasibility 23 Hall Creek H&H Study Lake Ballinger 24 Watershed & Water Quality 25 Federal Lobbyist Survey for construction 26 projects (non CIP) Capital Improvement Projects Ballinger Park/Hall 27 Creek Project (Phase II) Police Station 28 Stormwater Pipe Replacement 56th Avenue West Area 29 Stormwater Replacement Projects

4-20 November 2018

2019 $0

2020 $4,000,000

2021

2022 $5,000,000

2023 $0

2024 $1,600,000

2025 $0

2026 $1,600,000

2027 $0

2028 $1,600,000

$15,000

$4,035,000

$25,000

$5,025,000

$25,000

$1,625,000

$25,000

$1,625,000

$25,000

$1,625,000

$3,190,046

$6,258,963

$5,131,268

$9,768,949

$6,993,761

$8,149,158

$7,544,609

$9,163,925

$9,465,398

$11,414,357

$107,288

$112,632

$116,011

$119,492

$123,076

$126,769

$130,572

$134,489

$138,524

$142,679

$2,000

$2,000

$60,000 $113,000 $200,000 $13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$15,000

$15,000

$15,300

$15,606

$15,918

$16,236

$16,561

$16,892

$17,230

$17,575

$20,000

$20,000

$20,400

$20,808

$21,224

$21,649

$22,082

$22,523

$22,974

$23,433

$175,000

$1,750,000

$400,000

$300,000

$1,000,000

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-6 – (continued) 10-Year Financial Forecast Analysis (2019-2028) Line No.

Revenue 66th Avenue West Pipe 30 Replacement Taylor Pond 31 Rehabilitation Cedar Way Dam Pond 32 Rehabilitation Hall Creek Flood 33 Abatement Project 34 Spot Repair Program Road Related Upgrade 35 Program Aging Infrastructure 36 Replacement Program Total Construction 37 Related Costs: TOTAL EXPEND & 38 OTHER USES ENDING FUND BALANCES: Reserved for: Outstanding 39 Encumbrances: Operating Reserve - 15% 40 of Operating Expenses.

Reserved for Debt 41 Service Designated/Reserved– 42 Construction ENDING FUND 43 BALANCES:

2019

2020

2021

2022

2023

2024

2025

2026

2027

2028

$566,000 $295,000 $470,000 $500,000 $200,000

$210,000

$220,500

$231,525

$243,101

$255,256

$268,019

$281,420

$295,491

$200,000

$105,000

$110,250

$115,763

$121,551

$127,628

$134,010

$140,710

$147,746

$300,000

$500,000

$1,100,000

$1,100,000

$1,600,000

$1,648,000

$1,697,440

$1,748,363

$1,800,814

$1,230,888

$1,429,232

$1,450,311

$4,350,256

$2,091,106

$2,642,906

$2,213,699

$2,286,973

$2,362,821

$2,441,338

$3,885,016

$4,654,991

$4,420,350

$7,366,089

$5,503,888

$6,103,823

$5,835,971

$5,959,853

$6,199,596

$6,331,334

$0

$0

$0

$0

$0

$0

$0

$0

$0

$0

$288,156

$373,900

$293,542

$300,411

$307,454

$314,674

$322,077

$329,668

$337,453

$345,436

$733,091

$733,091

$1,013,091

$1,013,091

$1,363,091

$1,363,091

$1,475,091

$1,475,091

$1,587,091

$1,587,091

($1,716,217)

$496,981

($595,715)

$1,089,357

($180,672)

$367,570

($88,530)

$1,399,313

$1,341,257

$3,150,496

($694,970)

$1,603,972

$710,918

$2,402,860

$1,489,872

$2,045,335

$1,708,638

$3,204,072

$3,265,801

$5,083,023

City of Mountlake Terrace Comprehensive Stormwater Plan

4-21 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-7 20-Year Financial Forecast Analysis (2029-2038) Line No. Revenue 2029 REVENUES AND OTHER SOURCES: BEGINNING FUND 1 $5,083,023 BALANCES OPERATING REVENUES ERUs (Billable as 2 14,446 factored) ERU Monthly 3 $38.33 Service Rate Stormwater Rate 4 $6,643,815 Revenues Connection Charge 5 Revenue $115,144 ($245/connection) Connection Charge $1,339 Fee 6 Investment Interest $76,245 7 Other Revenues $13,600 Total Operating 8 $6,848,805 Revenue EXPENSES OPERATING EXPENDITURES 9 Debt Service $1,699,091 Stormwater 10 Maintenance (Non$1,862,019 street sweeping) Regulatory 11 $331,039 Compliance 12 Street Sweeping $164,429

4-22 November 2018

2030

2031

2032

2033

2034

2035

2036

2037

2038

$5,377,625

$5,849,867

$6,700,797

$7,758,324

$9,271,846

$10,861,707

$12,695,608

$14,611,512

$16,609,052

14,533

14,620

14,708

14,796

14,885

14,974

15,064

15,154

15,245

$39.86

$41.45

$43.11

$44.84

$45.73

$46.65

$47.58

$48.53

$49.50

$6,951,180

$7,272,505

$7,608,930

$7,960,634

$8,168,688

$8,381,881

$8,600,905

$8,825,337

$9,055,900

$121,142

$125,988

$132,534

$137,835

$142,189

$145,033

$149,596

$152,588

$157,369

$1,392

$1,448

$1,506

$1,566

$1,598

$1,630

$1,662

$1,695

$1,729

$80,664 $13,600

$87,748 $13,600

$100,512 $13,600

$116,375 $13,600

$139,078 $13,600

$162,926 $13,600

$190,434 $13,600

$219,173 $13,600

$249,136 $13,600

$7,166,587

$7,499,841

$7,855,576

$8,228,443

$8,463,555

$8,703,439

$8,954,535

$9,210,697

$9,476,004

$1,699,091

$1,509,091

$1,509,091

$1,272,091

$1,272,091

$1,104,091

$1,104,091

$1,104,091

$1,104,091

$1,905,717

$1,950,524

$1,996,471

$2,043,591

$2,091,915

$2,141,480

$2,192,318

$2,244,468

$2,297,965

$339,453

$348,100

$356,986

$366,119

$375,507

$385,156

$395,076

$405,274

$415,759

$168,299

$172,267

$176,336

$180,508

$184,787

$189,175

$193,676

$198,293

$203,028

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-7 – (continued) 20-Year Financial Forecast Analysis (2029-2038) Line No.

Revenue 2029 TOTAL 13 OPERATING $4,056,578 EXPENDITURES Operating Revenues over (under) Operating 14 $2,792,227 Expenditures OTHER FINANCING SOURCES Intergovernmental 15 $25,000 (i.e., Grants) Revenue Bond 16 $0 Proceeds Total Other Financing 17 $25,000 Sources TOTAL REVS & 18 $11,956,828 OTHER SOURCES CAPITAL EXPENDITURES: Engineering Admin.

19 Charge (Operating & $146,960 Construction) Other Professional Services Telemetry System 20 Controls Stormwater Rate 21 Study Ballinger Park/Hall 22 Creek Analysis Hall Creek H&H 23 Study Lake Ballinger 24 Watershed & Water $13,600 Quality 25 Federal Lobbyist $17,926

City of Mountlake Terrace Comprehensive Stormwater Plan

2030

2031

2032

2033

2034

2035

2036

2037

2038

$4,112,560

$3,979,982

$4,038,884

$3,862,309

$3,924,300

$3,819,902

$3,885,161

$3,952,125

$4,020,843

$3,054,027

$3,519,859

$3,816,691

$4,366,134

$4,539,255

$4,883,537

$5,069,373

$5,258,572

$5,455,161

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$0

$0

$0

$0

$0

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$25,000

$12,569,212

$13,374,707

$14,581,373

$16,011,768

$17,760,401

$19,590,146

$21,675,143

$23,847,209

$26,110,056

$151,369

$155,910

$160,587

$165,405

$170,367

$175,478

$180,742

$186,164

$191,749

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$13,600

$18,285

$18,651

$19,024

$19,404

$19,792

$20,188

$20,592

$21,004

$21,424

$0

$0

4-23 November 2018

Gray & Osborne, Inc., Consulting Engineers

TABLE 4-7 – (continued) 20-Year Financial Forecast Analysis (2029-2038) Line No.

Revenue Survey for 26 construction projects (non CIP) Capital Improvement Projects Spot Repair 34 Program Road Related 35 Upgrade Program Aging Infrastructure 36 Replacement Program Total Construction 37 Related Costs: TOTAL EXPEND 38 & OTHER USES ENDING FUND BALANCES: Reserved for: Outstanding 39 Encumbrances: Operating Rsve – 40 15% of Oper. Exp. Reserved for Debt 41 Service Designated/ 42 Reserved – Construction ENDING FUND 43 BALANCES:

4-24 November 2018

2029

2030

2031

2032

2033

2034

2035

2036

2037

2038

$23,902

$24,380

$24,867

$25,365

$25,872

$26,390

$26,917

$27,456

$28,005

$28,565

$310,266

$325,779

$342,068

$359,171

$377,130

$395,986

$415,786

$436,575

$458,404

$481,324

$155,133

$162,889

$171,034

$179,586

$188,565

$197,993

$207,893

$218,287

$229,202

$240,662

$1,854,839

$1,910,484

$1,967,798

$2,026,832

$2,087,637

$2,150,266

$2,214,774

$2,281,217

$2,349,654

$2,420,144

$2,522,625

$2,606,785

$2,693,928

$2,784,164

$2,877,613

$2,974,394

$3,074,636

$3,178,469

$3,286,032

$3,397,467

$6,579,203

$6,719,346

$6,673,910

$6,823,049

$6,739,922

$6,898,694

$6,894,538

$7,063,631

$7,238,157

$7,418,311

$0

$0

$0

$0

$0

$0

$0

$0

$0

$0

$353,623

$362,020

$370,634

$379,469

$388,533

$397,831

$407,372

$417,161

$427,205

$437,513

$1,699,091

$1,699,091

$1,509,091

$1,509,091

$1,272,091

$1,272,091

$1,104,091

$1,104,091

$1,104,091

$1,104,091

$3,324,911

$3,788,755

$4,821,073

$5,869,764

$7,611,222

$9,191,784

$11,184,145

$13,090,261

$15,077,755

$17,150,141

$5,377,625

$5,849,867

$6,700,797

$7,758,324

$9,271,846

$10,861,707

$12,695,608

$14,611,512

$16,609,052

$18,691,745

City of Mountlake Terrace Comprehensive Stormwater Plan

Gray & Osborne, Inc., Consulting Engineers

GRANT AND LOAN PROGRAMS Grants and loans can be used to fund capital improvement projects, but cannot be used to fund operation and maintenance. Within the State of Washington, there are several grant and loan funds available for capital improvements. Among these are the Public Works Trust Fund, Centennial Clean Water Fund, and the State Revolving Fund. The various grant and loan programs are briefly described below for reference.

Public Works Trust Fund This program is a revolving fund loan designed to help local governments finance needed public works projects through low-interest loans and technical assistance. It was established by the Washington State Legislature in 1985, and is administered by the Public Works Board. The State offers emergency, pre-construction (i.e., design) and construction loans. At the time, no constructions funds are available, although the State noted that funds may be available in the 2019-2021 funding cycle if the budget is approved by the legislature. Although loan repayments and tax revenue streams that fund the program will continue to be deposited in the fund, it is uncertain what level of funding may be available through the program in the near future.

Department of Ecology Water Quality Combined Funding Program The Department of Ecology administers several loan and grant programs that can be used to fund the following: • • • • • • • •

Stormwater capital improvements including stormwater system retrofits Low-impact development projects Inventories of stormwater sources Public education and communication Review and preparation of stormwater regulations Mapping Source control activities Establishing and refining stormwater utilities

The funding programs include the following: •

Clean Water Act Section 319 Grant program: Federal and State funds used for nonpoint source pollution control projects.

•

Centennial Clean Water Program Grant program: State funds that provide grants for water quality infrastructure and nonpoint source pollution projects such as stream restoration and buffers, on-site septic repair and replacement, as well as education and outreach.

City of Mountlake Terrace Comprehensive Stormwater Plan

4-27 November 2018

Gray & Osborne, Inc., Consulting Engineers

•

Clean Water State Revolving Fund Loan program: Federal and State funds that provide low-interest and forgivable principal loan funding for nonpoint source pollution control projects and eligible “green” projects.

•

Stormwater Financial Assistance Grant Program: State funds that provides grants for stormwater projects to reduce impacts from existing infrastructure and to enhance existing stormwater projects.

•

Stormwater Capacity Grants Program: State funds awarded to Phase I and Phase II NPDES Permittees for activities and equipment necessary for permit implementation. Historically, these non-competitive grants have ranged from $25,000 to $50,000 per year.

With the exception of the Stormwater Capacity Grants, a common application is available for funding from the Ecology-administered programs. The programs are competitive and the majority of the funding available is in the form of low-interest loans or grants with matching requirements.

DEBT FINANCING Two forms of debt financing are available for capital improvements including general obligation bonds and revenue bonds. General obligation bonds are backed by the “full faith and credit of the City” and are paid for through property tax levies. These bonds require voter approval before they can be implemented. A less common means of financing capital improvements associated with stormwater projects is through the use of revenue bonds. The City, like other municipalities, is capable of issuing tax-exempt bonds. The principal and interest of such bonds are repaid from revenue generated from a utility, such as a water, sewer, or stormwater utility. This type of funding may be offered without voter approval. However, in order to qualify to sell revenue bonds, the City must establish that its net operating income is equal to or greater than its debt coverage factor, typically 1.25 at a minimum (but 2.0 is preferred), multiplied by the annual principal and interest due for all outstanding bonded indebtedness. The City has historically been utilizing revenue bonds and as shown in Tables 4-6 through 4-7, the financial analysis includes extending the use of revenue bonds to help pay for future infrastructure needs.

4-28 November 2018

City of Mountlake Terrace Comprehensive Stormwater Plan

APPENDIX A COST ESTIMATES

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE CIP No. C1 (66th Ave. W. Pipe Replacement) July 2018 G&O# 17507 NO. 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

DESCRIPTION

QUANTITY

SPCC Plan Mobilization Project Temporary Traffic Control Traffic Labor and Spotter Traffic Labor Police Offficial Survey and Asbuilts Trench Excavation Safety Systems Shoring Structrual Excavation Sawcutting Remove and Dispose of Existing Asphalt Pavement Dewatering Bank Run Gravel for Trench Backfill Solid Wall CPEP Storm Sewer Pipe, 42 In. Diam. (Incl. Bedding) Remove and Dispose of Storm Pipe Catch Basin, Type 2 Crushed Surfacing Base Course HMA, CL 1/2-in PG 64-22 Temporary Erosion Control

1 1 1 180 120 1 1 1 290 110 1 320 240 240 2 50 90 1

LS LS LS HR HR LS LS LS LF SY LS TN LF LF EA TN TN LS

PRICE $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $

1,500 26,000 30,000 75 150 10,000 10,000 35,000 5 35 10,000 50 250 35 5,000 45 200 5,000

AMOUNT $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $

1,500 26,000 30,000 13,500 18,000 10,000 10,000 35,000 1,450 3,850 10,000 16,000 60,000 8,400 10,000 2,250 18,000 5,000

Subtotal Construction Contingencies (20%)

$ $

278,950 55,790

Total Construction Cost (rounded)

$

334,740

Topographic Survey Base Map (4%) Engineering Services (20%) Construction Adminstration (17%) Permitting (15%)

$ $ $ $

13,390 66,948 56,906 50,211

Total Project Cost (rounded)

$

523,000

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE CIP P1 (Taylor Pond Rehabilitation) July 2018 G&O# 17507 NO. 1.

2.

3.

4.

5.

6.

7.

8.

9.

$ $ $ $ $ $ $ $ $

AMOUNT 500 15,000 10,000 2,500 10,000 81,000 25,000 10,000 5,000

Subtotal Construction Contingencies (20%)

$ $

159,000 31,800

Total Construction Cost (rounded) Engineering Services (20%) Construction Adminstration (17%)

$ $ $

191,000 38,200 32,470

Total Project Cost (rounded)

$

262,000

ITEM SPCC Plan Mobilization/Demobilization Force Account As-Built Drawing Remove and Dispose of existing shrubs, vegetation Sediment Removal Replant new vegetation Quarry Spall Rock for Engergy dissipation Erosion/Water Pollution Control

Note: Assumes 1.5' depth of sediment removal.

UNIT PRICE QUANTITY 500 1 LS 1 LS $ 15,000 1 EST $ 10,000 1 LS $ 2,500 1 LS $ 10,000 540 CY $ 150 1 LS $ 25,000 1 LS $ 10,000 1 LS $ 5,000

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE CIP No. S2 (Cedar Way Dam Rehabilitation) August 2018 G&O# 17507 $ $ $ $ $

AMOUNT 18,000 11,250 7,500 16,800 140,000

Subtotal Construction Contingency (20%)

$ $

193,550 38,710

Total Construction Cost (rounded)

$

232,000

Topographic Survey Base Map (4%) Engineering Services (20%) Construction Adminstration (17%) Permitting (25%)

$ $ $ $

9,280 46,400 39,440 58,000

Total Project Cost (rounded)

$

386,000

NO. ITEM 1. Mobilization/Demobilization 2. Excavate Sediment 3. Load and Hault Silt from Pond 4. Quarry Spall Access Rehabilitation 5. Sediment Diversion Area

QUANTITY 1 LS 150 CY 150 CY 140 TN 1 LS

UNIT PRICE $ 18,000 $ 75 $ 50 $ 120 $ 140,000

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE Typical Cured-in-Place Cost Estimate July 2018 G&O# 17507 $ $ $ $

AMOUNT 4,000 5,000 3,000 26,800

$

38,800

Total Construction Cost (rounded)

$

39,000

Topographic Survey Base Map (4%) Engineering Services (20%) Construction Adminstration (17%) Permitting (15%)

$ $ $ $

1,560 7,800 6,630 5,850

Total Project Cost (rounded)

$

61,000

Typical CIPP Project Cost for 18-inch Pipe: Typical CIPP Cost for 12-inch Pipe

$ $

183 170

NO. ITEM 1. Mobilization/Demobilization 2. Force Account 3. Project Temporary Traffic Control 4. Cured-in-Place Pipe, 18-Inch Diameter

QUANTITY 1 LS 1 EST 1 LS 335 LF Subtotal

UNIT PRICE $ 4,000 $ 5,000 $ 3,000 $ 80

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE Typical Pipe Bursting Cost July 2018 G&O# 17507 $ $ $ $ $ $

AMOUNT 2,000 5,000 3,000 8,000 3,500 26,800

$

48,300

Total Construction Cost (rounded)

$

49,000

Topographic Survey Base Map (4%) Engineering Services (20%) Construction Adminstration (17%) Permitting (15%)

$ $ $ $

1,932 9,660 8,211 7,245

Total Project Cost (rounded)

$

76,000

Typical Pipe Bursting Project Cost for 12-inch Pipe:

$

230

NO. ITEM 1. Mobilization/Demobilization 2. Force Account 3. Project Temporary Traffic Control 4. Trench Excavation Safety System 5. Excavation Pit and Restoration 6. Pipe Bursting, 12-Inch Diameter

QUANTITY 1 LS 1 EST 1 LS 1 LS 1 EA 335 LF Subtotal

UNIT PRICE $ 2,000 $ 5,000 $ 3,000 $ 8,000 $ 3,500 $ 80

Note: Assumes pits are outside/adjacent to paved areas. Additional cost should be included if pits are within the pavement.

CITY OF MOUNTLAKE TERRACE COMPREHENSIVE STORM SYSTEM PLAN UPDATE PLANNING LEVEL COST ESTIMATE Typical Sliplining Cost July 2018 G&O# 17507 $ $ $ $ $ $

AMOUNT 5,000 5,000 3,000 8,000 2,500 25,125

$

48,625

Total Construction Cost (rounded)

$

49,000

Topographic Survey Base Map (4%) Engineering Services (20%) Construction Adminstration (17%) Permitting (15%)

$ $ $ $

1,945 9,725 8,266 7,294

Total Project Cost (rounded)

$

76,000

Typical Sliplining Project Cost for 12-inch Storm Pipe (per LF):

$

230

NO. ITEM 1. Mobilization/Demobilization 2. Force Account 3. Project Temporary Traffic Control 4. Trench Excavation Safety System 5. Excavation Pit 6. HDPE Slipline Pipe 10-Inch Diameter

QUANTITY 1 LS 1 EST 1 LS 1 LS 1 EA 335 LF Subtotal

UNIT PRICE $ 5,000 $ 5,000 $ 3,000 $ 8,000 $ 2,500 $ 75

Note: Assumes pits are outside/adjacent to paved areas. Additional cost should be included if pits are within the pavement.