8.15.23 Sewerability Presentation

2023 Rural Sewer Capability Study Overview

Urban Growth Management Master Plan Advisory Committee

August 15, 2023

Charles H. Martin, P.E. Director Division of Water Quality

• How topography drives a sewer system layout • 2023 Study methodology – key points

• Potential regulatory obligations

• Committee questions, comments, discussion

• 14 areas included in study.

• Topography influences the menu of alternatives in some areas.

• The drainage engineer perspective: contours and catchments define service area boundaries – not property lines and roads.

HYPOTHETICAL DRAINAGE EXAMPLE

• Sewer systems operate best like a bathtub – the outlet (drain) is the treatment plant.

• If you divide the bathtub into parts with no drain, you have to pump to a drain.

• Fayette County has eight main bathtubs (and multiple smaller ones) and only two drains (treatment plants).

Study Methodology Highlights

RURAL SERVICE AREA (RSA) LIST

Gross Acres Verses Developable Acres

2There are no known Special Natural Protection Areas in the study areas

1Rural Residential Parcels are parcels 10 acres or less and zoned residential

Study Approach Capital Cost

• Methodology – proprietary costing tool developed by Hazen

• Same costing tool used to project Consent Decree capital construction costs

• Estimates do not include design fees, property acquisition costs and other administrative costs (legal, project management, inspection, etc.)

Study Approach - Capital Cost

• Capital cost estimates were developed for all “plausible” alternatives within each study area. Those cost estimates were combined with the developable acres estimate to make a comparative “Cost per Developable Acre” metric.

• Metric serves as a basis of cost / benefit but is not absolute because:

• Area geometries may be adjusted in a way that impacts the amount of developable acres and/or the cost to serve the adjusted acre total.

• Some alternatives require more LFUCG existing customer cost participation than others. The fiscal impact of those outcomes have not been fully evaluated.

LFUCG Customer Cost Example

• Downstream infrastructure in an Expansion Area could potentially serve existing upstream customers.

• In most cases, it should, to avoid system inefficiencies.

• Cost of the new downstream infrastructure should be flow proportional:

• X% of flow existing customers / Y% of flow new development.

• X% of cost existing customers / Y% of cost new development.

OTHER STUDY METHODOLOGIES OF NOTE

• Evaluated downstream controls for RSAs are either:

• Pump stations, or

• Pump stations with storage tanks, or

• A wastewater treatment plant

• Downstream controls are not a collection of small pumping stations dedicated to specific parcels or developments.

OTHER STUDY METHODOLOGIES OF NOTE

Wastewater infrastructure may be located within parcels that participated in the PDR Program if it maximizes the efficiency for conveying flows in an RSA.

OTHER STUDY METHODOLOGIES OF NOTE

• As any sanitary sewer system ages, wet weather flows increase due to Inflow and Infiltration (I/I). The study considers this unavoidable circumstance in its future flow projections and costs.

• In terms of infrastructure, the study assumes that no I/I is directly conveyed to a treatment plant, instead it is stored at the pump station site until downstream capacity is restored.

REGULATORY

IMPACTS OF EXPANSION

New Wastewater Treatment Plant Scenario

Estimated time – 15 years

REGULATORY IMPACTS OF EXPANSION

Existing Wastewater Treatment Plant Scenario

Estimated time – 5 years

REGULATORY IMPACTS OF EXPANSION Population Growth

• If growth plans identify the need to serve more than 30 percent additional equivalent population, a new Facility Plan must be submitted and approved by the state.

• Lexington’s 30% threshold: 30% of 346,007 = 103,802.

• At a projected density of 15 ppl per acre, developable acreage trigger is 6,920 acres. At 21 ppl per acre, developable acreage trigger is 4,943 acres.

REGULATORY IMPACTS OF EXPANSION Treatment Plant Capacity

Kentucky Administrative Regulations obligate utilities to develop and implement capacity management plans when plant capacity reaches 95%.

Where you expand and where the sewage goes impacts this trigger.

TOWN BRANCH WEST HICKMAN

Committee Questions, Comments and Discussion on How to Make Next Meeting Productive