A Toolkit for Stormwater Best Management Practices for Urban Farming

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

Prepared by: The University of the District of Columbia (UDC), Constituent Services Worldwide, and Groundsmith Collective, in partnership with Low Impact Development Center (LID)

Copyright © 2021 by the University of the District of Columbia (UDC) All rights reserved. This document reflects the collaborative work of the University of the District of Columbia (UDC), Constituent Services Worldwide, and Groundsmith Collective, in partnership with Low Impact Development Center (LID). The partners hold the copyright of the materials produced of this toolkit.

No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher and collaborators, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. For permission requests, write to a project lead.

PROJECT LEADS: Harris Trobman, Project Specialist, CSDR, CAUSES, UDC Email: harris.trobman@udc.edu, Phone: 202-274-6682 Neil Weinstein, Executive Director, The Low Impact Development Center, Inc. Email: nweinstein@lidcenter.org, Phone: 301-982-5559 Hossain Azam, Ph.D., P.E., Asst. Professor of Env. Eng., CE, SEAS, UDC Email: hossain.azam@udc.edu, Phone: 202-274-6293 Jacob Wynn, Graduate Student, CAUSES, UDC Email: Jacob.wynn@udc.edu, Phone: 847-544-8423 PROJECT ASSOCIATE LEADS: Kamran Zendehdel, Ph.D., Acting Director, CSDR, CAUSES, UDC Elizabeth Gearin, Project Specialist, Urban Planning, CAUSES, UDC Tolessa Deksissa, Ph.D., Director, WRRI, CAUSES, UDC Kelley Oklesson, Groundsmith Collective, Principal Designer Saba Hamidi, Saba Hamidi Design, Creative Director, Lead Designer PROJECT REVIEWERS: Pradeep Behera, Ph. D., P.E., Professor and Head of Civil Engineering, SEAS, UDC Sarah Waickowski, P.E., Extension Associate, Biological and Agricultural Engineering, NCSU STUDENT CONTRIBUTORS: Brandon Hunt, Graduate Student, CAUSES, UDC Stephanie Fuentes, Graduate Student, SEAS, UDC Assefa Tadesse, Undergraduate Student, CE, SEAS, UDC Lirane Mandjoupa, Undergraduate Student, SEAS, UDC PROJECT PARTNERS: College of Agriculture, Urban Sustainability, and Environmental Sciences (CAUSES), School of Engineering and Applied Sciences (SEAS) and Low Impact Development Center (LID) ACKNOWLEDGMENT: This project was funded by National Fish and Wildlife Foundation (NFWF)

CONTENTS PURPOSE

3

1

URBAN FARMING

4

2

URBAN FARMS & STORMWATER

12

3

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

26

4

GREEN STORMWATER INFRASTRUCTURE

36

CONCLUSION

61

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

PURPOSE This toolkit provides an overview and guidance on potential stormwater impacts and subsequent pollution control practices of urban farming in the Chesapeake Bay watershed. The aim of this toolkit is to support the expansion and environmental resilience of urban farms throughout the region.

OBJECTIVES: To demonstrate the importance of stormwater management for urban farming and community gardening.

To provide guidance on stormwater pollution types, stormwater runoff impacts and mitigation strategies for urban agriculture.

To summarize advantages and disadvantages of best management practices (BMPs) related to urban farming for the planning, maintenance, and long-term sustainability of an urban farm and community level pollution reduction.

To guide those aspiring to farm in an urban context with tools and support to address the health, safety, and welfare of impacted communities.

3

CHAPTER 1

URBAN FARMING Urban Farming Types of Urban Farms Benefits & Challenges Future of Urban Farming & Climate Change

4

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

5

URBAN FARMING

URBAN FARMING WHAT IS URBAN FARMING United State Department of Agriculture (USDA) defines urban agriculture (UA) as the production, distribution, and marketing of food and other products within the geographical limits of a metropolitan area. This includes community and school gardens, backyard and rooftop plots, and non-traditional methods of growing plants and animals within a constrained area. Urban agriculture systems are highly diverse in size, form and function and can be found in different types of urban spaces from vacant lots to roofs, backyards and streets (RH).

TYPOLOGY OF URBAN AGRICULTURE USDA classifies urban farms into four general categories as shown below: 1. Institutional Farms and Gardens: Typically linked with an institution (such as hospitals, churches, prisons, schools, public housing) whose primary mission is not large-scale food production, but instead to provide health, educational, and lifestyle opportunities. Furthermore, it can be adopted at small scale in household level in the backyard or in the roof as well.

2. Community Gardens: Usually located on publicly owned land or land trusts and managed by local resident volunteers. Community gardens are mostly used to grow food, but some also can be used for growing flowers. Some community gardens provide space for community gatherings and events.

3. Community Farms: Typically operated by a nonprofit organization in communal growing spaces that engages the surrounding community in food production as well as social and educational programming.

4. Commercial Farms: Practiced for profit in urban areas by commercial growers. Although commercial farms tend to be small and often produce niche products. Some small urban commercial farms focus on non-traditional growing techniques like vertical or soil-less farming.

These four types of UA use one or a combination of the following practices and structures to grow food. Each interacts and affects with stormwater quality differently and the next chapters will explain how stormwater can become a problem as well as the potential solutions to effectively control stormwater pollution originating from urban farms.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

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TYPES OF URBAN FARMING

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7

URBAN FARMING

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8

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

BENEFITS Urban farms and gardens can provide economic, social, and environmental benefits to a neighborhood while offering physiological, nutritional and psychological benefits to its residents. (ARB) (HLT). Some of the urban agriculture benefits are as follows: ࢙ Connects urban residents to food systems. ࢙ Improves food security in urban areas through access to fresh and nutritious food. ࢙ Improves health conditions such as obesity, diabetes through physical activity and nutrition. ࢙ Provides opportunities for outdoor activities. ࢙ Provides opportunities to socialize, cooperate with friends and family. ࢙ Creates space for interracial and intercultural exchange. ࢙ Supports cultural heritage of citizens through access to ethnic foods. ࢙ Helps gardeners and urban farmers gain new knowledge and technical skills. ࢙ Decreases local crime rate. ࢙ Increases property value of surrounding area. ࢙ Increases green space and reduces urban heat island (UHI) effects ࢙ Alleviate direct peak run-off and flash flood concerns of urban areas while recharging the ground water.

9

URBAN FARMING

CHALLENGES STORMWATER

The National Water Quality Assessment shows that rural agricultural runoff is the leading cause of water quality impacts to rivers and streams, the third leading source for lakes and the second largest source of impairments for wetlands (EPA2). While the full environmental impacts of urban farming have yet to be fully assessed, each urban farming practice can potentially compromise the surrounding watershed by allowing pesticides, nutrients, and sediments into the local watershed via stormwater runoff.

To learn more about your waterway, visit “HOW’S MY WATERWAY?” at: https://mywaterway.epa.gov URBAN SOILS Urban soils can be a challenge to urban farms as they can be highly compacted, and frequently contaminated due to years of industrial and development activities. Prior to any farming activities, it is important to test and evaluate the soil at the site to determine levels of pollution and subsequent remediation required. Deep tillage, addition of compost and use of cover crops can dramatically improve infiltration and water holding capacity while making metals such as lead and cadmium less mobile in soil, reducing uptake by plants (ARB).

Overall, despite the challenges, scientific literature shows that the benefits of UA practices provide more benefits in comparison to the potential challenges present with respect to human health and urban environment (HLT). Furthermore, those challenges can be addressed by adopting a number of different available strategies to make urban farming sustainable for urban farmers. The purpose of this toolkit is to introduce and provide techniques to urban growers to reduce the environmental impacts of planning, developing and maintaining an urban farm.

10

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

FARMING IN THE CONTEXT OF FUTURE CITIES Urban agriculture is seen as a promising practice to contribute to more sustainable and resilient urban communities. It contributes to higher food security in urban areas, and can be considered as a new educational, participatory and citizenship strategies. Wide adoption of urban farming is inevitable to provide sustainable solution to water-energy-food-climate nexus related challenges in cities specially when low-income urban households spend 60–80% of their income on food specially in developing countries. The Food and Agriculture Organization (FAO) of the United Nations P O P U L A T I O N FA C T O I D : (UN) reports that 800 million people worldwide grow vegetables or fruits or raise animals in The populations of the world’s cities cities, supplying 15 to 20% of the world’s food are expected to increase from demand in urban areas (FD).

55% of the 7 billion today (2021) Recent policy adjustment in major US cities to 68% of the ~9.5 billion projected for 2050 have paved the pathway to incorporate UA into the fray of commonality amongst city dwellers.

(United Nations) The new policy changes reduce barriers to adopt urban farms and increase urban food production in economically, environmentally, and socially sustainable ways. This trend is expected to grow increasingly as urban areas will be home for more than 68% of the World’s population by 2050.

CLIMATE CHANGE AND STORMWATER This growing trend of urban agriculture is occurring against a backdrop of global climate change, in which the Chesapeake Bay region is particularly vulnerable. The Chesapeake Bay region can expect climate change in form of increasing intensity and frequency of storm events -- heavier downpours followed by hot, dry periods (Fourth National Climate Assessment, US Global Change Research Program). Changes in the intensity and timing of rain events can impact the quantity and quality of stormwater that cities and urban farms must plan for.

Considering the multi-faceted pressures, the urban environment presents, it is no longer justifiable for urban agriculture to solely focus on production. There is a great opportunity to include stormwater management best management practices (BMPs) as a part of UA design. Green infrastructure, a BMP approach, offers a promising new approach to manage quality and quantity of stormwater. By handling stormwater at its source, green infrastructure can reduce the volume of water and remove pollutants that would otherwise flow through traditional stormwater systems (ARB) (STT). Incorporation of green infrastructure BMPs into the urban agriculture site design can ensure urban resiliency in the era of climate change.

Thus, these best management practices not only can reduce pollution load and dampen peak run-off from urban farms but also can provide additional ecosystem services to the community. Thus, urban farming can be an integral part of new sustainable city model.

11

CHAPTER 2:

URBAN FARMS & STORMWATER What is Stormwater and why is it a challenge?

Urban Water Cycle & Urban Farms Stormwater Management Pollution Related to Urban Farming Activities & Impacts on the Chesapeake Bay

12

WHAT IS STORMWATER AND WHY IS IT A CHALLENGE? Rainfall, the lifeline of any farm, meets the water demand of plants of any farm but can lead to environmental challenges when it turns into stormwater runoff. Stormwater runoff is any precipitation (e.g. rainfall) that does not evaporate or percolates into the ground, but instead collects and flows over the surface into storm drains, rivers and streams. Increased development across the Chesapeake Bay watershed has made stormwater the fastest growing source of pollution to the Bay (EPA). Stormwater originating from urban farms are expected to carry pollution from soil to the discharge point of the farm and might need intervention to prevent them from entering our waterways.

So, stormwater in urban areas poses challenges related to both water quantity and quality. First, as urban areas are mostly impervious, rain cannot percolate easily into the soil and can generate a significant amount of stormwater with direct runoff stressing the drainage systems. This can also cause flooding and erosion in the area. Second, water quality of stormwater gets affected by contaminants that exist in urban areas and can be picked up by stormwater during overland flow ending up in a river, stream or lake. The environmental damage caused by stormwater pollutants not only harms wildlife but also affects humans in various ways such as contaminating drinking water.

As a part of the urban landscape, urban farming has both positive and negative impacts to the quantity and quality of stormwater runoff. These impacts will become more prominent as urban agriculture and gardening rapidly expand in the coming years. Some municipalities may require urban farms to develop a stormwater management plan. So, a proper understanding how typical farming activities are connected to this pollution will help all scales and types (home, community, commercial) of urban farmers and gardeners to plan their stormwater pollution control strategies accordingly. This chapter explains how rainfall becomes stormwater, the types of pollutants relevant to urban farms and impacts of this polluted stormwater runoff on the natural environment and the specific roles of urban farms to stormwater quantity and quality.

13

URBAN FARMS & STORMWATER

PERVIOUS VS. IMPERVIOUS SURFACES NATURAL GROUND COVER

(Zero to Minimal Human Impact to Soil Structure)

URBAN SETTING: 75%-100% IMPERVIOUS COVER (Extensive to Extreme Human Impact to Soil Structure)

40% EVAPOTRANSPORTATION 30%

10%

STORMWATER RUNOFF

55%

25% SHALLOW INFILTRATION 10%

25%

DEEP INFILTRATION

5%

URBAN WATER CYCLE The natural water cycle allows for precipitation (e.g. rainfall) U R B A N FA C T O I D : to be absorbed by soil and plants, recharge the groundwater, Washington D.C. is evaporate and transpire through the leaves of plants as they grow. Development activities disrupt this cycle, replacing plants and open space with hard non-porous concrete and metal.

These impervious surfaces can’t absorb water like plants and IMPERVIOUS soil, so it remains on the surface and leads of surface runoff/ SURFACES stormwater. Water that is not absorbed can accumulate quickly: one inch of rain falling on an acre of hardened surfaces can produce up to 27,000 gallons of runoff (CBF). Despite this, every four years land development continues to add an average of 40,000 acres (about the size of Washington, DC) of impermeable surfaces across the Chesapeake Bay watershed (CBF2).

43%

C HAPTER E E

4

Reverting urban spaces such as compacted vacant lots back into more natural areas such as urban agriculture can decrease stormwater runoff by up to 85 percent! (STT). However, placing structures such as hoop houses on urban lots may actually increase the lot’s impervious surface and create increased runoff. Incorporating water re-use systems that collect runoff from structures for re-use, can help address this challenge. Furthermore, most types of urban farms can increase pervious surfaces in urban setting and can increase percolation of water to groundwater.

S

STORMWATER ON URBAN FARMS

RAINWATER HARVESTING

14

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

STORMWATER MANAGEMENT In order to prevent flooding and property damage stormwater is conveyed away through a series of underground sewer systems throughout the city. There are two distinct types of sewer systems: the combined sewer system (CSS); and the municipal separate storm sewer system (MS4). The CSS combines stormwater with the sanitary system and transports the mix to a wastewater treatment plant. This system was effective when it was put in place, but as urbanization has increased impervious areas. The excess water can overwhelm the system (see Combined Sewer Overflows). Thus, MS4 was developed to exclusively transport stormwater to nearby receiving bodies of water, such as Rock Creek, Anacostia and Potomac rivers. Because stormwater travels over the land, it picks up all types of pollutants on the way to the sewer.

These pollutants (e.g. nutrient, total suspended solids) may have detrimental effects on the river and streams they are discharged into, and these effects are compounded as the water from multiple rivers flows into the Chesapeake Bay (CBF2).

POINT SOURCE POLLUTION

!

Check your government agency to determine which sewer system your property falls into.

IMPACTS OF RUNOFF Uncontrolled stormwater discharge results in cumulative effects on humans and the environment that includes the Chesapeake Bay region. Different effects can be:

COMBINED SEWER OVERFLOWS (CSOS) Combined Sewer Overflows (CSOs) are a large source of pollution for bodies of water in DC. These occur during rain events that exceed the capacity of the combined sewer system. When this occurs, regulators are designed to let the mixture of stormwater and sanitary waste discharge directly into the District’s rivers & creeks.

POLLUTANTS IN RUNOFF 1. Pesticides and herbicides 2. Road Salt 3. Toxic Metals including copper, lead, & zinc 4. Fecal Bacteria 5. Nitrogen & phosphorus 6. Soil & sediment 7. Oil & other petroleum products 8. Trash 15

࢙ Erosion- sediment clogging of waterways, reduction of water clarity ࢙ Widened Stream Channels - loss of valuable property ࢙ Effects on Aesthetics - dirty water, trash and debris, foul odors ࢙ Impaired Fish and Aquatic Life impaired and destroyed (lead to dead zones) ࢙ Impaired Recreational Uses swimming, fishing, boating ࢙ Threat to Public Health contamination of drinking water, fish/ shellfish ࢙ Threat to Public Safety – injuries and drownings occur in flood waters ࢙ Economic Impacts – impairments to related businesses (fisheries, shellfish, tourism, recreation etc.), increased cost of water and wastewater treatment.

URBAN FARMS & STORMWATER

The Chesapeake Bay watershed consists of a network of 100,000 streams river and creeks that all flow into the Bay, connecting different states and regions SOURCE: https://www.cbf.org/about-the-bay/maps/geography/major-river-watersheds-of-the-Chesapeake-bay.html

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

FARMING IN THE CONTEXT OF URBAN STORMWATER

While urban agriculture can dampen the peak runoff and can reduce stormwater quantity by increasing groundwater recharge, it can also potentially negatively affect stormwater quality.

For example, a common urban farming activity such as adding nutrients to the soil can lead to high nutrient concentrations in any runoff originating from urban farms. This diagram provides a few examples of how urban farms can contribute to the eight different pollutants of urban stormwater runoff. Unintended contamination of stormwater can occur during use or storage. In the following sections of the toolkit, the urban farming activities that lead to unintended pollution are discussed further as well as how this pollution affects the Bay’s fragile ecosystem.

17

URBAN FARMS & STORMWATER

POLLUTANTS IN RUNOFF

1

PESTICIDES AND HERBICIDES Spray and pellets that dissolve in water

2

ROAD SALT Gets carried with snow and ice melt

3

TOXIC METALS Heavy metals such as copper exist in herbicides, roofing materials, paints, or even might already exist in urban soil

4

FECAL BACTERIA Generates from waste of farm animals and pets.

5

NITROGEN & PHOSPHOROUS Comes from soil additives applied during farm establishment and maintenance.

6

SOIL & SEDIMENT Generates from exposed soil, stockpiles, and amendments.

7

OIL & PETROLEUM PRODUCTS Originates from generators, tilling machines, cars in parking lots.

8

TRASH Originates from various sources from seed packets to visitor’s lunches.

With projected increases for the localized demand in farming sites, these negative effects will be compounded as each new farm adds to the cumulative effects in the same watershed. Although the intention is not to pollute, many common farming practices can lead to environmental degradation through the cumulative process. Fortunately, as an emerging land use, urban agriculture can take lessons from urban construction and large-scale rural agriculture to minimize their impact through the use of Best Management Practices (BMP) (ARB). Chapter 3 will detail these BMP and their implementation practices.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

ACTIVITIES & IMPACTS ON THE CHESAPEAKE BAY Pollutant:

SOIL & SEDIMENTS

Pollution Potential Activities: ࢙ Destabilizing soil through vegetation removal ࢙ Construction activity without stormwater management ࢙ Uncovered stockpiles and soil amendments Impacts on The Bay:

19

MANAGE EROSION & SEDIMENT RUNOFF

E SE

SE

APTER 3 -

CH

APTER 3 -

COVER & PROTECT MATERIALS

0 P.3

Solution:

CH

9 P.2

E

Poor agriculture practices, that accelerate soil loss, increase the amount of sediment that flows into the Bay. When water becomes cloudy with excess sediment, it blocks sunlight from penetrating the water column. Sunlight is vital to the growth of critical underwater grasses that provide necessary habitat for fish, crabs, and food for waterfowl (CBF).

URBAN FARMS & STORMWATER

Pollutant:

TRASH & ROAD SALT

Pollution Potential Activities: ࢙ Leaving a farm in an unorganized and unkempt state ࢙ Improperly disposed trash ࢙ Improper/overuse of road salt Impacts on The Bay:

SE

Solution:

CH

APTER 3 -

GOOD HOUSEKEEPING

1 P.3

E

Not only does trash tarnish the natural beauty of an area, it also smothers aquatic plants and bottom dwelling organisms, adds toxic contaminants to the water, and lead to animal diseases.

Elevated chloride levels from road salt damage the natural balance of aquatic animals.

While the aquatic organisms in the Chesapeake Bay are resistant to a level. But fluctuating levels of the contributing streams and rivers affect the freshwater and elevated chloride levels in these bodies cause malformations, slow growth rate, and affect egg development.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

ACTIVITIES & IMPACTS ON THE CHESAPEAKE BAY (CONT.)

Pollutant:

PESTICIDES AND HERBICIDES, TOXIC METALS, OIL AND PETROLEUM PRODUCTS

Pollution Potential Activities: ࢙ Using spray pesticides, and herbicides as pest management ࢙ Running generators or till machines ࢙ Rubber, oils, and metals from cars in parking lot Impacts on The Bay:

21

SE

Solution:

CH

APTER 3 -

INTEGRATED PEST MANAGEMENT

2 P.3

E

Many of these products are carcinogenic, and oil and petroleum products are toxic to aquatic life even in low concentrations. They disrupt the entire food web through a process of bio-accumulation. Small bottom-dwelling organisms take up the contaminants as they feed. As they are consumed by larger fish the toxins accumulate to toxic levels. This continues up the food chain to waterfowl, humans, and other wildlife (CBF).

URBAN FARMS & STORMWATER

Pollutant:

NITROGEN & PHOSPHOROUS / FECAL BACTERIA

Pollution Potential Activities: ࢙ Overuse of chemical fertilizers and nutrients ࢙ Chickens or other small animals that generate waste ࢙ Uncovered composting or other organic material stockpiles Impacts on The Bay:

SE

Solution:

CH

APTER 3 -

MANAGE NUTRIENTS

3 P.3

E

Nitrogen and phosphorus pollution feeds algal blooms that suck oxygen from the water creating “dead zones”. These low oxygen areas remain the main challenge to Bay restoration as they hamper the Bay’s capacity to support aquatic life (CBF). Additionally, fecal bacteria can be of concern from poorly treated sewage especially from decentralized systems.

22

Total Maximum Daily Loads (TMDLs) for different water bodies if they are in violation of water quality standards.

The Clean Water distinguishes between point andFARMING non-point sources of stormwater A TOOLKIT FOR STORMWATER BEST Act MANAGEMENT PRACTICES FOR URBAN discharge, while TMDLs calculate how much of a pollutant a water body can handle and still meet water quality standards.

Enacted by Legislation in 1972

PIPES

POINT SOURCE POLLUTION

NON-POINT SOURCE POLLUTION

DITCHES RUNOFF OVER ROADS, SIDEWALKS, ETC.

TOTAL MAXIMUM DAILY LOADS Every two years, each state reports which water bodies don’t meet water quality standards. Then, in order to restore those water bodies back to levels that do meet standards, each water body, like the Chesapeake Bay, as well as smaller tributaries like Rock Creek & the Potomac and Anacostia Rivers, is assigned TMDLs for different pollutants such as organics, metals, bacteria, or suspended solids.

ORGA NIC

.

ER T AT

SOLIDS . ME TA LS

IA TER AC .B

M

In other words, a body of water that does not meet quality standards, must go on a ‘Pollution Diet’ in order to reduce pollution levels. This is done through implementing cost-effective solutions that deal directly with stormwater runoff issues in each area.

WATER QUALITY STANDARD POLLUTION DIET TOTAL MAXIMUM DAILY LOAD

THE CLEAN WATER ACT OF 1972 and subsequent clean water policy provides guidelines for Stormwater Management (SWM) through a permitting process that adheres to pollution limits called the Total Daily Maximum Load (TMDL). Please refer to your local government for more information as well as appendix A for a historical timeline of Federal water regulation.

23

D.C. STORMWATER REGULATIONS

The DC government must fulfill requirements of the Municipal Separate Storm Sewer System (MS4) URBAN FARMS & STORMWATER permit (mandated by the EPA), which documents its stormwater management program implementation, continued monitoring, and compliance of discharges into water bodies in Washington D.C.

:

(MS4 Permit)

MUNICIPAL SEPARATE STORM SEWER SYSTEM

LOCAL ENVIRONMENTAL REGULATORS H DI S C

TI

E C O MP

L

CE

NG

M

CON

G AR

N IA

R

T

RI

RA

ST O

D M O NI

O

E NU

G

M

TER PR O WA

To meet compliance, specific laws, regulations, and programs are put in place to guide how to prevent and handle stormwater runoff.

Incentive Programs

Land Disturbance + 5000 SF?

EN

GIN

EER

MAJOR LAND-DISTURBANCE AREA

NA

L

Many municipalities have stormwater reduction incentive programs that offer financial incentives and funding for voluntary stormwater projects including credits or rebates. Check with your local agency to find these programs along with other ways to save money while doing your part to protect the environment.

PROF E SSIO

EROSION & SEDIMENT CONTROL (ESC)

Significant land disturbing activity may require a professional engineer to develop an erosion & sediment control (ESC) plan. Check with your local environmental agency for regulations.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

25

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

CHAPTER 3:

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES Performing a Stormwater Pollution Inspection Overview: Best Management Practices Pollutant Reduction Strategies Native Plants

26

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

PERFORMING A STORMWATER POLLUTION INSPECTION To determine whether the stormwater on your property is contaminated, take the following steps to perform a basic ‘stormwater pollution inspection’: 1. VISUALLY INSPECT PROPERTY ࢙ Walk around property ࢙ Inspect areas of concern ࢙ Find storm drains 2. FIND POTENTIAL SOURCES ࢙ Storage ࢙ Areas that are high traffic/activity ࢙ Spills 3. RECORD FINDINGS ࢙ Be honest ࢙ Take pictures 4. TAKE CORRECTIVE ACTION ࢙ Fix any issues ࢙ Take preventive measures ࢙ Raise awareness

https://www.youtube.com/watch?v=p9OniVkfkVI&feature=emb_logo DOEE. Check the website EPA. Some non-profit organizations offer free site evaluations 27

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

OVERVIEW: BEST MANAGEMENT PRACTICES Best management practices (BMP) are implemented on urban farms to help reduce total contaminants on site. By adjusting standard practices with considerations for stormwater, urban farmers can do their part to reduce pollution. These practices may require different types of resources or minor physical changes but are cost effective and provide multiple benefits.

MANAGE SOIL EROSION & SEDIMENT RUNOFF

(Minimizing soil disturbance, mulching, cover crops)

Use of well-known techniques to reduce erosion by limiting soil exposure, disturbance and improving soil.

COVERING/PROTECTING MATERIALS

(Tarps, overhangs, pallets raised off ground)

The partial or total physical enclosure of materials, equipment, or process operations typically found on an urban farm. Might require some initial capital cost.

GOOD HOUSEKEEPING

(Visual sweeping, storage, labeling materials) Reduce unintended pollution, waste and hazards around the farm.

INTEGRATED PEST MANAGEMENT (IPM)

(Minimize herbicide & pesticide use)

A multi-faceted approach to managing crop damaging pests without the overuse of chemical herbicides and pesticides.

NUTRIENT MANAGEMENT

(Minimize fertilizer use)

Alternative approaches to ensure plants thrive while reducing amount of excess nutrients that make it to the storm drain. Can improve soil health and are cost effective.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

POLLUTION REDUCTION STRATEGIES

MANAGE SOIL EROSION & SEDIMENT RUNOFF ࢙ Employ cover crops

Reduce erosion from wind and water.

Restore soil and increase the organic matter content.

࢙ Use mulch

Minimizes soil disturbance by wind or rain Retain and increase soil’s nutrients

࢙ Build terraces, berms, filter strips & conservation landscaping to act as buffers Prevents any eroded sediment from leaving the site.

࢙ Add organic matter to rebuild soil ࢙ Utilize conservation tillage techniques that minimize soil disturbance ࢙ Use silt fencing, waddles, straw bales and other temporary erosion sediment controls during construction activities ࢙ Avoid heavy machinery to prevent compaction Maintain current infiltration rates minimizing flooding

29

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

COVERING & PROTECTING MATERIALS ࢙ Stockpile like materials (compost, mulch, soil, pesticides etc.)

Avoids unintentional application

࢙ Compost in bin with lid and tarp raised off the ground to protect from water Prevents leachate and nutrient contamination

࢙ Fully cover soil piles with tarp

Reduces material loss from wind and rain

࢙ Locate materials as much as possible undercover and away from drainage paths Avoids potential pollutants encountering stormwater

࢙ Store all nutrients in containment pallet and under cover ࢙ Protect ground underneath any equipment to avoid grease and oil ࢙ Frequently inspect high risk areas Minimize unintentional pollution

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

POLLUTION REDUCTION STRATEGIES (CONT.) GOOD HOUSEKEEPING ࢙ Properly storing and labeling materials

Avoids any accidental contamination or spills.

࢙ Visually inspecting and correcting actions

Identifies potential issues prior to them becoming a problem.

࢙ Maintaining a clean and orderly operation Clean spills when they occur.

࢙ Composting organic waste

Lowers carbon footprint by reducing methane emissions in landfills.

Can be added back into soil to boost productivity.

࢙ Properly disposing of trash and waste Prevents pest harborages.

Sets a tone of discipline and order.

࢙ Track inventories with accessible clipboard

Keeps a record of potential hazards and production

࢙ Keep a spill kit in case of hazardous spills

31

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

INTEGRATED PEST MANAGEMENT (IPM) This is a strategy that prevents pest damage with minimum adverse impact on human health, the environment and non-target organisms. The term “pest” refers to more than one cause and includes diseases, undesirable insects, mites, mollusks, nematodes and weeds. In IPM programs, growers use their knowledge of crop and pest biology to take actions that reduce the environment’s suitability for pest establishment and increases in pest populations. IPM employs careful monitoring techniques and combinations of biological, cultural, mechanical, chemical and environmental or physical controls.

Pesticides are used only when monitoring indicates that they are needed. If pesticides are necessary, they are chosen and applied in a way that avoids disrupting other IPM practices.

MINIMIZE HERBICIDE USE Like the misuse of fertilizers, misuse or overuse of herbicides has the potential to pollute our waterways. Avoiding or minimizing herbicides protects farmers from exposure to herbicides that can cause physical harm to humans, from skin irritation to birth defects in unborn babies. Minimizing herbicide use also mitigates against the chemical pollution of air, water and soil from herbicides; and the potential for herbicides to stimulate undesirable algae growth. Alternatives to herbicide use include the following: ࢙ Pluck out unwanted plants before seeding in order to contain the growth and spread of weeds. ࢙ Use mulch or tarps to suppress weeds and retain soil moisture.

MINIMIZE PESTICIDE USE Minimizing the use of pesticides reduces the loss of these materials to the environment and encourages the efficient use of other insecticides to protect crops and waterways.

Alternatives to pesticide use include the following: ࢙ Biologic controls. ࢙ Introduction of insects or bacteria that do not hurt plants and that attack pests. ࢙ Companion planting-plant multiple types of crops in the same field rather than just one specific type. Crop varieties differ in their susceptibility to pests and diseases and in their ability to compete with weeds.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

POLLUTION REDUCTION STRATEGIES (CONT.) NUTRIENT MANAGEMENT ࢙ Organic alternatives such as fish emulsion, compost, and manure rebuild soil improving carbon sequestration and water retention ࢙ Cover crops revitalize and protect the soil reducing nutrient loss when not in production. ࢙ Precisely calculate quantity and frequency of application. ࢙ Check soil prior to use and only apply where needed.

33

POLLUTION REDUCTION STRATEGIES: BEST MANAGEMENT PRACTICES

NATIVE PLANTS Recall: Stormwater is generated as a result of the reduction of natural areas due to development. Returning areas to their pre-developed conditions by creating spaces that are not exclusively focused on production is a simple and cheap way urban farmers can reduce and filter stormwater runoff while adding substantial benefits to the farm.

Wild Strawberries (Fragraria virginiana and F. vesca)

Red Mulberry (Morus rubra)

Serviceberry (Amelanchier arborea)

American papaw (Asimina triloba)

Raspberries, Blackberries, & Dewberries (Rubus sp.)

Blueberries (Vaccinium sp.)

NATIVES SPECIES Native plants are flowers, ferns, trees, shrubs and grasses that have always grown in the Chesapeake Bay Region (NTV). They are better adapted to local soils, climates and pests so they require much less work. Their ability to grow better root systems help them absorb significantly more water, improving pollutant uptake and water treatment (STT). Because they evolved together, these species provide the best resources (food, homes, medicines) for wildlife, and will attract pollinators and pest predators.

Creating spaces for these species to proliferate will integrate both stormwater and ecosystem benefits into the farm. Some important native species include: Biodiversity supporting, food and flower producing, native varieties. The Fish and Wildlife Guide referenced in the resources section provides a complete a list of beneficial native species to consider when creating these spaces.

TREES While all native species provide benefits trees are a special case. Trees help clean the air, sequester carbon, absorb water, reduce the urban heat island effect. Native species, such as the eastern hemlock support biodiversity. Fruit and nut trees, such as the chokeberry can also be planted for an additional production benefit.

WEEDING & CARE Even though native plants are adapted to the climate and soil placing them in the right micro-regions to ensure they receive the right combination of water and sun is essential to their survival. Ensuring their health by removing weeds and watering when needed during establishment, will enable the most effective stormwater management and can also help minimize weed intrusion in production areas.

The next chapter discusses further stormwater management techniques through the use of advanced BMPs called green stormwater infrastructure that take advantage of specific properties of plants to treat and retain stormwater.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

35

CHAPTER 4:

GREEN STORMWATER INFRASTRUCTURE Green Stormwater Infrastructure Site Assessment Urban Agriculture Map Green Infrastructure Integrated with Urban Farms

36

A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

GREEN STORMWATER INFRASTRUCTURE In chapter 3 we discussed simple low-cost practices to reduce the risk of pollution leaving your farm area. The next step to consider is managing that runoff with Green Stormwater Infrastructure (GSI). GSI is an umbrella term for any project that limits runoff from flowing into storm drains. Harnessing the power of the vegetative process alongside engineered soils and retention structures GSI aims to mimic the natural hydrologic cycle and return sites to their pre-development conditions. These techniques can range from simple applications to complex structures, and this chapter explains how GSI can be integrated into urban farming.

37

GREEN STORMWATER INFRASTRUCTURE

SITE ASSESSMENT Performing a proper site assessment before installing any GSI is necessary to understand the particular conditions that your site presents. Based on the outcome of the assessment you will be able to choose from following GSI to maximize your stormwater management through aesthetic, air purifying techniques.

Utilize this checklist to determine how, where, and how much stormwater accumulates on your property.

SITE CONTEXT Lot size, property type, proximity to local water bodies, as well as general watershed information, such as average rainfall. Aerial views from local government websites will help with the layout of any projected plans. ࢙ Microclimate - Adjacent structures and existing vegetation that create solar and wind exposure all create conditions that are ideal for some plants, but not others. Considering how these conditions will change with intended use should also go into plant selection choices. ࢙ Solar/ Wind Exposure - These components are important details and help determine feasibility of your project.

࢙ Sewer System - Where are the storm drain located near or on the property and what system they

drain to. ࢙ Depth to Water Table - The water table is the level at which the groundwater normally sits. If there is a relative small depth to the water table GSI won’t infiltrate properly because water is already present.

SITE CONDITIONS ࢙ Impervious surfaces - area of them including roofs important for calculating contributing drainage area ࢙ Downspouts - The number of downspouts and whether or not they are connected to the storm drain might add to the CDA if disconnected even if the roofs themselves are not on the property. ࢙ Topography - Direction and severity of slope length and steepness. ࢙ Drainage Ways - Look to how stormwater is already flowing on site and pay attention to any areas that appear eroded. Working with these natural drainage areas will avoid the expense of creating artificial ones. They can be improved through creating vegetative buffers and amending eroded areas. These flow paths will help inform the location for GSI. ࢙ Existing Vegetation - Identify layers of vegetation, such as tree canopy extent, and major invasive, native, and non-native plants. Develop a plan for removal of any hazardous or invasive species in and around the project area. Protect trees and vegetation when possible, and transplant healthy plants when necessary. Ground cover is the most important factor in preventing erosion as it shields the soil from raindrops and the roots hold it in place.

SOIL CONDITIONS A soil probe can be used to determine the soil type and make-up. Along with a compaction assessment, this can help determine whether or not stormwater will infiltrate into the soil in grassy areas. ࢙ Contributing Drainage Area - Knowing the area of impervious surfaces, topography, and soil composition all go in to calculating the contributing drainage area for any GSI. The outcome of these calculations will determine the sizing and/or amount of GSI needed for your site. The EPA now has an app that makes it easy to get an estimate of your CDA. ࢙ Utility Location - Know where gas, water, sewer, electric, cable, and telephones lines are located overhead and underground. Call Miss Utility! (811) for information before digging under-utilized areas.

SOURCES: http://www.stormwater.allianceforthebay.org/riverwise-communities-manual/assessments http://cdnassets.hw.net/6f/66/e6cf4a584c8bb6573dc63d10ad6a/lid-national-manual.pdf http://documents.philadelphiawater.org/gsi/GSI_Landscape_Guidebook.pdf https://www.grownyc.org/files/osg/green_infrastructure_techniques_WEB.pdf

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

URBAN AGRICULTURE MAP

39

GREEN STORMWATER INFRASTRUCTURE

GREEN INFRASTRUCTURE

1

CONSERVATION LANDSCAPING A technique using native species to filter and absorb runoff in under-utilized areas.

2

FILTER STRIPS Permeable vegetated areas that act as buffers, filtering and slowing runoff

3

RAIN GARDENS Small, vegetated depression that retain and treat stormwater on site.

4

VEGETATED SWALES Linear channels that treat stormwater as it is conveyed towards a storm drain

5

WOODCHIP BIOREACTORS Open topped boxes filled with woodchips that provide water quality treatment for rain barrels.

6

RAIN BARRELS/ CISTERNS Collect and store runoff from rooftops in waterproof containers.

7

PLANTER BOXES Small scale bioretention systems contained in boxes that help manage stormwater from downspouts near buildings.

8

PERMEABLE PAVEMENT The use of specially designed paving materials that allow for the rain to flow through them.

9

GREEN ROOFS Layered rooftop systems that support plant growth, absorbing and evaporating a portion of stormwater.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

41

GREEN STORMWATER INFRASTRUCTURE

GREEN INFRASTRUCTURE INTEGRATED WITH URBAN FARMS

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

CONSERVATION LANDSCAPING Conservation Landscaping, also known in the Chesapeake Bay area as Bayscaping, is the practice of replacing grass, bare soil, or invasive plants with native species. These species, with their deeper root systems absorb much more water facilitating infiltration and treatment of runoff.

RELEVANCE OF CONSERVATION LANDSCAPING TO URBAN FARMING

Not only does conservation landscaping provide an aesthetically pleasing example of native plants, it can also appeal to beneficial insects that will help pollinate food crops or protect them. The landscaping will improve soil quality while trapping any runoff and can be used in of crop rotation cycle.

Here conservation landscaping is being used as a form of erosion control and beautification of a slope.

43

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A CONSERVATION LANDSCAPE

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

KEY TERM:

INFILTRATION

The vertical movement of water through soil or porous material and reloading of groundwater.

Figure 1: https://www.riversmarthomes.org/bayscaping

There are several considerations to take into account when designing a conservation landscape: LOCATION: The placement of the landscaping is important. While the majority of its benefits can be reaped regardless of where it is placed on the farm, in order to maximize its stormwater treatment potential, it should be placed in direct line of the flow paths that were discovered during site assessment, or alternatively, on areas that are of particular concern for erosion.

PLANTS CHOICE: The location of Bayscaping will affect several variables such as sun, soil type, and drainage, that will determine which type of plants should be selected. These same location considerations for plant selection apply to all vegetated BMP in this chapter. For more information on native plant varieties and their specific needs refer to Appendix B.

MAINTENANCE: Like any area on a farm these plants will require some routine maintenance. During establishment (1 -2 growing seasons), proper watering, weeding and mulching will ensure they take a stronghold of the area. Once established these plants require little extra help.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

FILTER STRIPS Vegetated strips of land next to farmed areas provide filtration buffers between site activities and stormwater drains. Filter strips are also referred to as pretreatment when used in combination with other GSI. The vegetation slows the flow of runoff, reducing risks of erosion, and filters out sediment and other pollutants.

RELEVANCE OF FILTER STRIPS TO URBAN FARMING

Similar to the rural application, urban farms can reduce their pollution potential by maintaining a filter strip to act as a buffer between the farm and storm drains or waterbodies. These buffers can also provide visual cues to pedestrians and vehicles of farm boundaries. Using conservation landscaping brings all the benefits of that practice as well. Planting in between rows or raised beds with simple grass strips can act add additional erosion control.

45

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A FILTER STRIP

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

KEY TERM:

INTERCEPTION

Figure 1: Interception and slowing of sheet flow seen from above with eddies around individual grass stems comparing to impervious surface with speed arrows, along with combination of these three cross sections.

The slowing down of stormwater accumulation by blocking the path it travels with leaves, stems and other plant parts.

SOURCE: https://www.hertfordshire.gov.uk/microsites/building-futures/a-sustainable-design-toolkit/ technical-modules/water/solutions.aspx

Filter strips are designed to manage runoff in the form of sheet flow, or water that flows at an even depth across a designated area and should not be located at an outlet or where water concentrates. Planting along a gentle slope keeps stormwater moving along slowly and allows for infiltration.

Filter strips can be installed as simply as planting grass in an unused area or along the natural drainage ways. More complex applications include engineering slopes as part of other GSI or adding gravel trenches ahead of the filter strips to disperse more concentrated flows across the width of the strip.

MAINTENANCE varies by location and composition. Mowing, weeding, and watering during establishment, as well as removal of sediment build up or debris are typical.

Figure 2: https://www.researchgate.net/publication/237346517_Vegetative_Filter_Strips_for_Nonpoint_Source_ Pollution_Control_in_Agriculture

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

RAIN GARDENS As the most fundamental forms of bioretention, rain gardens are designed to retain and slowly infiltrate runoff into groundwater after a storm. Pollutants are absorbed and filtered through specifically designed soil medium and vegetation.

RELEVANCE OF RAIN GARDENS TO URBAN FARMING

Applying the rain garden concept into site design farmers can give their production beds dual functionality.

Utilizing conservation landscaping in a traditional rain garden will still bring the biodiversity benefits important to any farm. Additionally, the substantial filtration capacity of rain gardens makes it an ideal place to drain nutrient heavy hydroponic or aquaponic systems.

47

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A RAIN GARDEN

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

KEY TERM:

BIORETENTION

Figure 2http://www.stormwater.allianceforthebay.org/take-action/installations/rain-gardens#resources

Once the site assessment is finished, farmers can apply what they learned to design an effective rain garden.

Rain gardens are often bean shaped to capture as much runoff from the CDA as possible. Pretreatment in the form of filter strips help slow sheet flow where needed.

Most soils will need some amendments to ensure it has both good drainage and provides enough nutrients for plant growth.

Using soil that was dug up for berm construction on the downslope portion of the garden, and a plan in place for any unused soil will help manage the risk of sediments leaving the site. To establish a ponding depth an overflow outlet is installed at the maximum height. For large storms this outlet will allow the rain garden to drain excess water into storm drain.

Designs that temporarily hold or retain stormwater in an area and treat it with biologically active components such as microbes, soil, and plants.

PLANTS: Apply previous concepts from conservation landscaping and site assessment for plant selection. Plants able to withstand submersion in water should be placed in the center, with lessening degrees nearer the exterior of the garden.

MAINTENANCE: Typical weeding and watering during plant establishment as well as removal of sediment and debris is required.

Rain gardens will pond after a storm but should infiltrate within 72 hours. Longer retention times may indicate clogging and should be monitored.

https://www.harvestingrainwater.com/plant-listsresources/rain-garden-planting-zones/

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

VEGETATED SWALES A vegetated swale utilizes a combination of rain gardens, filter strips, and conservation landscaping to create a conveyance system that directs runoff away from the property, towards a storm drain. These swales slow, filter, absorb, and infiltrate much of the stormwater that runs through them, and if designed correctly, not much actually reaches the drain.

RELEVANCE OF VEGETATED SWALES TO URBAN FARMING

Vegetated swales are adaptable and can range in scale based on the needs of the farm. Providing similar benefits as rain gardens and conservation landscaping, these swales offer another option for farms with limited infiltration capacity or heavy flows from impervious areas.

49

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A VEGETATED SWALE

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

KEY TERM:

CONVEYANCE

https://water.rutgers.edu/Green_Infrastructure_Guidance_Manual/GI-Brochure_PRINT-FRIENDLY.pdf

The linear transportation or movement of water across a surface or through a pipe.

Vegetated swales are the most common form of stormwater management due to their low cost of construction and maintenance.

While multiple forms of a vegetated swale exists, the concept of stormwater conveyance remains consistent. Many of the same design parameters are required when designing a swale as the previous GSI. Sizing the swale will be based on CDA calculations. Filter strips provide effective pretreatment and sheet flow dispersion of runoff to minimize erosion. The slope of the swale needs to be steep enough so that water flows in one direction and does pool, but shallow enough that allows time for some water to infiltrate. Most swales lead to a storm drain so knowing the location of the nearest drain as well as the drop in elevation will be key parameters for the design. Swale conceptual design can be applied to farming practice as a means of transporting water throughout the farm or away from areas that frequently flood.

MAINTENANCE: Swales act as a means of conveyance so any standing water represents a blockage that will need to be remediated through removal of debris or sediment.

Mowing of the pretreatment and ensuring chosen plants flourish weed removal is required during the establishment phase.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

WOODCHIP BIOREACTOR

Through years of experimentation rural farmers have found that adding woodchip bioreactors to filter strip buffers is an effective way of removing nitrate from agricultural runoff. Certain bacteria when submerged in water can use nitrogen instead of oxygen to help them create energy when eating. In this case the bacteria break down the carbon source (woodchips) for food using the energy supplied by the fertilizer.

RELEVANCE OF WOODCHIP BIOREACTORS TO URBAN FARMING

While this practice has traditionally been used in rural applications there is potential for adaptation to an urban setting. With proper scaling and design woodchip bioreactors could be another tool urban farmer have to deal with high nutrient loads. This practice could be used as a stand-alone or combined with other GSI.

51

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A WOODCHIP BIOREACTOR

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

KEY TERM:

TREATMENT

Bioreactors consist of ditches or small pits filled with a slow releasing carbon source. Woodchips are most often used because of their availability and relative cheap cost. Rural bioreactors use drainage tile, or large lightweight pipes beneath fields to direct flow into the bioreactors. Urban farms can make use of a similar type of conveyance system or develop a novel system for site specific application. The scale of the bioreactor is determined by the runoff conditions of the site (volume, flow rate, and nutrient load) and should be designed to meet these parameters. (BIR)

The bacteria present in bioreactors is one way that GSI treats storm water. These bacteria are present in most soils, but woodchips increase their effectiveness.

Other mechanisms of treatment include absorption and uptake via plants and filtration of physical particles.

DE-NITRIFICATION

should occur so long as: 1. Temperatures are high enough to support bacteria 2. Water is retained for enough time 3. There is enough nitrate to break down in the water 4. Oxygen doesn’t become available to bacteria

MAINTENANCE: Bioreactors are relatively low maintenance and as long as they are designed correctly should function for 4 years with little need for correction. Addition of new woodchips is the main activity required, and the conveyance system should be checked periodically for clogging.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

RAIN BARRELS / CISTERNS

Rainwater harvesting is the collection of rainwater from impervious surfaces for later use.

Rainwater collection systems divert roof downspouts to cisterns or rain barrels. Rain barrels and cisterns are the containers that hold the captured stormwater. Rain barrels are typically used for smaller properties such as private residences whereas cisterns are typically used for larger commercial properties.

RELEVANCE OF RAIN BARRELS/CISTERNS TO URBAN FARMING

Capturing and storing rainwater from the rooftops situated around the urban farm comes with several benefits. Initially, capturing stormwater reduces the amount of stormwater that runs through the farm. This reduces erosion and any potential nutrient loss that might end up as pollution, keeping soil and nutrients in place. Additionally, the farm can save on water costs by reusing the captured water for irrigation on certain plant types and non-edible species.

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GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A RAIN BARREL / CISTERN

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

http://pvcguy.com/downspoutdiverters/

Rain barrels are an easy DIY installation with relatively low input costs. Cisterns are much more expensive and require engineers with construction plans to install (1).

INSTALLATION: Diverters - Connect rain barrels directly to downspout system with downspout diverters.

These come in many forms and require specific gutter cutting tools.

Barrels - should be placed on an even graded surface elevated slightly on cinder blocks to improve drainage for use. Barrels are sized based on the CDA calculations and may be linked in sequence for larger areas or desired holding capacity. Barrels can be any large food grade container that is waterproof, and many municipalities have rebate programs to help with the costs of purchase.

Overflow/Spigot - Overflow protection is important to prevent damage to other areas of the system and should either flow back into the storm drain or to another GSI. Spigot are placed at or near the bottom with a hose attachment to allow for emptying and use after the storm event.

Pretreatment - Screens or other forms of filter will keep debris out the barrel and prevent clogging.

MAINTENANCE: Inspect - During a rainstorm make sure all parts are working and there are no unintended leaks.

Drain/Use - Barrels should be emptied between each storm.

Winterizing - In order to avoid freezing during winter months barrels need to be drained and disconnected.

Algae - Barrels should be opaque or kept out of sunlight to prevent algae growth.

Mosquitoes - A tight sealing lid will ensure these pests can’t use your barrel to lay their eggs.

Cleaning - Any debris such as leaf build up should be removed from the pretreatment as needed.

APPLICATION: Water collected from rain barrels is not considered safe to drink and should only be used on nonedible plants or trees. Draining barrels into other GSI practices is a great way to maintain both.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

PLANTER BOXES Planter boxes are a versatile green infrastructure that perform the same functions as larger practices on a smaller scale. Built within boxes or containers, their defined size adheres to many functional areas and can be used as a welcome aesthetic improvement to numerous locations. The vegetative box is intended to be placed next to buildings and installed with a waterproof liner. Once the soil becomes saturated, the excess water collects in an underdrain system where it may be routed to a storm water conveyance system or another GSI system, such as a vegetated swale (2).

RELEVANCE OF PLANTER BOXES TO URBAN FARMING

As a versatile stormwater solution practice planter boxes provide many potential benefits to multiple types of urban farms. Acting as a natural filter, planter boxes can help reduce nutrients levels in water drained from aquaponic/hydroponic systems during cleaning. For rooftop gardening planter boxes can act as an excellent wind barrier as well as offer some cooling shade. Planter boxes are particularly adaptive to an urban setting because they are self-contained modular units that can adhere to numerous applications.

https://www.epa.gov/sites/production/files/2015-10/documents/neosho-handbook-508.pdf

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GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A PLANTER BOX

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

The design of planter boxes combines the collection concepts of rain barrels with the passive treatment capabilities of rain gardens. Essentially these boxes create a rain garden within a rain barrel. Some specific engineering is required to allow for the passive drainage of stormwater as opposed to the regular activity required of rain barrel maintenance. The boxes must be reinforced and waterproofed to hold soil, a gravel drainage layer, and the stormwater it was designed to collect from the roof. Using more than one box under multiple downspouts can help account for larger roofs and space limitations. Like a rain barrel, an overflow system is important for handling larger storms. A rock splash pad will keep the planter beautiful and avoid holes from forming in the soil media. Planters underlying drainage systems can lead to storm sewers or other GSI. PLANTS: Plants in the planter should be able to withstand dry and moist periods. Location of the planter will determine relative sun/shade varieties.

MAINTENANCE: Regular maintenance of a planter box includes weeding and watering like a rain garden. Regularly cleaning gutters will ensure debris doesn’t clog the planter. Any standing water indicates a clog system and will need remediation.

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

PERMEABLE PAVEMENT

Serving the same purpose as traditional paving surfaces, permeable pavements offer an alternative by filtering runoff through voids in the pavement surface and temporarily storing it in an underground stone reservoir. Here it returns to the storm sewer or slowly infiltrates (3).

RELEVANCE OF PERMEABLE PAVEMENT TO URBAN FARMING

Permeable pavement is designed for low impact application such as parking lots or recreation areas. An urban farm is an ideal place to consider using permeable pavements especially when impervious area is increased due to greenhouses. The extra firmness of permeable pavement is a great way to maintain perviousness in high foot traffic areas that become compacted over time.

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Porous Pave material maintains this pathway while allowing stormwater to filter through. https://biologicperformance.com/permeable-pavement/

GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD PERMEABLE PAVEMENT

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N : Easy

Difficult

Permeable pavement systems have low space requirements and can replace existing pavement systems. The underlying system facilitates stormwater capture with a gravel storage area that holds stormwater allowing it to slowly infiltrate into the soil. For areas with low rates of infiltration an under-drain can be installed to allow efficient drainage. The slope of bottom should be as close to zero as possible to avoid pooling. When installing near areas with high sediment loads such as garden beds a filter strip pretreatment is recommended to avoid clogging (3).

SURFACE: When designing a permeable pavement system there are many surface options to choose from with many that have similar appearance to traditional surfaces. Picking the right surface depends on purpose and price as some are more expensive than others. A newer type of surface called Porous Pave is recycled from old car tires and has the benefit of flexibility, as well as freeze and frost resistance (4) MAINTENANCE: Proper maintenance of permeable pavement is critical to its function.

Weeding and cleaning will ensure that the porous crevices don’t clog. Once a system is clogged it no longer serves stormwater benefit purposes and might as well be impervious.

Pictured: 3https://www.watershedcouncil.org/permeablepavers.html

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

GREEN ROOFS Green roofs are a planted growing media situated over a waterproof membrane to protect the roofing below. The plants absorb and evaporate a portion of rainfall to help reduce volume and peak runoff flows but are not meant to retain large storm events. Depending on the structural capacity of the roof, the depth of the growing layer can vary to support different sorts of plants. This practice is traditionally exclusively for stormwater retention and urban agriculture applications might not provide the same stormwater management properties (3).

RELEVANCE OF PERMEABLE PAVEMENT TO URBAN FARMING

Limited amounts of space and sun exposure as well as poor soil conditions contribute to difficulties of growing in an urban environment (5). Green roofs can combat these issues, by locating gardens on top of unused roof space in engineered media with plentiful sun. Provided the building has the underlying architecture to support intensive farming practices, rooftops open up huge possibilities for growing. Savings in heating and cooling of a building might help convince building owners to install one.

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GREEN STORMWATER INFRASTRUCTURE

!

HOW TO BUILD A GREEN ROOF

C O S T: Low

High

MAINTENANCE: Low

High

I N S TA L L AT I O N :

TYPE

DEPTH

Easy

GROWS

Extensive

3-6 inches

Succulents, herbs, & grasses

Semi-Intensive

6-10 inches

Grasses, herbaceous perennials, & shrubs

Intensive

10 or more inches

Supports trees & shrubs

Difficult

Table1: https://developersguide.njfuture.org/what-is-gi/

A structural engineer professional should be involved with all green roof designs to ensure that the building has enough structural capacity to support a green roof (3). The minimal requirements for support will allow for an extensive roof to range 3-8 inches of growing media.

For roofs with more substantial support intensive roofs can be planted with growing media up to 48 inches. Most vegetables crop varieties require at most 36 inches of growing depths and would be suitable for these intensive practices (6).

LAYERING: The layering system of a green roof is to ensure efficient drainage. The filter fabric and root barriers create a water permeable barrier that prevents solid from the growing media inundating runoff. Green roofs can be combine with other GSI such as rain barrels or planter boxes, and a vegetative swale or rain garden to accommodate larger storm events.

MAINTENANCE: Similar maintenance activities to most GSI green roofs require weeding and watering to help plants establish. Removing of debris and any sediment as well as inspection of any mechanical or structural components for functionality.

Proper drainage is of utmost importance as pooling or flooding brings high risk on rooftops.

Figure 4: https://doee.dc.gov/node/610622

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A TOOLKIT FOR STORMWATER BEST MANAGEMENT PRACTICES FOR URBAN FARMING

CONCLUSION As more and more people move into the urban environment, urban farming is a realistic solution to feeding the population. An urban farm is an ideal approach to sustainability, as it provides health in the form of fresh local nutritious food, outdoor door activity, and community engagement, creates stable long term in demand jobs and economic development, and provides a threshold for environmental education and concern. In order for these urban farms to ensure they represent this movement toward sustainable living, they must consider their impacts on the surrounding non-edible environment. While urban farms do provide a multitude of environmental benefits such as havens of biodiversity and reductions in stormwater quantity, many of the actions on these farms can contribute to pollution and environmental degradation as well. Simply by monitoring and implementing best management practices (BMPs), these farms can prevent much of this pollution from occurring in the first place. In situations where simple prevention is not enough, there are comprehensive steps that urban farmers can take to ensure any potentially damaging substances do not get discharged off their property by utilizing green infrastructure. This toolkit is meant to provide an introduction to these solutions and help urban farms live up to the potential of being sustainable hubs of life in an evergrowing city.

FUTURE PERSPECTIVE Climate change comes with more variable storm surges that are heavier and more frequent.

Understanding, how this stormwater moves on the urban farm property is important for many reasons described earlier in this toolkit. Pollution and environmental degradation are the top of the list, and urban farmers would be wise to utilize stormwater management during site design to reduce the economic impact of extreme storm events as well. Green infrastructure and urban farms both seek to improve the landscape by instilling an increased awareness of human environmental impact and green spaces within the city. According to the UN, sustainable urbanization is key to successful development. An integral aspect of implementing this is by maintaining linkages between rural and urban areas and urban agriculture can perform as a medium for informational exchanges between the two developing practices that improve both. Sustainable urban farming is achievable, and this toolkit provide major guidance for controlling polluted stormwater to protect our environment.

RESOURCES: DC Government Department of Energy and the Environment 2020 Stormwater Management Guidebook U.S. Fish & Wildlife Service Native Plants for Wildlife Habitats and Conservation Landscaping

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WORKS CITED 1. Alliance for the Bay. Rain Barrels. Reduce Your Stormwater. [Online] Alliance for the Bay. http://www.stormwater.allianceforthebay.org/take-action/installations/rain-barrels.

2. EPA. City of Neosho Green Infrastructure Design Handbook. [Handbook] Neosho : 2012 Green Infrastructure Technical Assistant Program, 2013. EPA 800-R-13-.

3. Hoffman, Greg, et al. Department of Energy and Environment. DC.gov. [Online] January 2020. https://doee.dc.gov/node/610622.

4. Biologic Performance. Permeable Pavement. Biologic Performance. [Online] Biologic Performance, 2021. https://biologicperformance.com/permeable-pavement/.

5. Edible green infrastructure: An approach and review of provisioning ecosystem services and disservices in urban environments. Russo, Alessio, et al. 242, Gloucestershire : University of Gloucestershire, 2017.

6. Lott, David E. and Hammond, Vaughn E. Water Wise, Vegetable and Fruit Production.

Lincoln : University of Nebraska, 2013.

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