Strategies for Coping with Polluted Runoff

Transcription

1 Strategies for Coping with Polluted Runoff Cooperative Extension Bringing the University to You Audiovisual C. Conway Strategies for Coping with Polluted Runoff Chris Conway Kennedy Jenks Consultants Susan Donaldson Melody Hefner University of Nevada Cooperative Extension Audiovisual This photo was taken near the Reno Costco on Harvard Way. Runoff from the parking lot west of Costco and the REI parking lot drains to this retention feature. This feature was originally designed to attenuate (slow down) storm water peak flows from the parking lots. Note the curb cut and rocklined channel that allows runoff while preventing erosion. The outlet from this constructed drainage feature ended up being above the gradient of the feature. This led to formation of a permanent pond, primarily from the irrigation of the grass on the embankments. Volunteer cattails have established themselves in the low point of the feature, the permanent pond. The vegetation is slowing down water flow into the storm drain and probably accomplishing some natural processing of pollutants. With more thoughtful design, this feature could accomplish even more water quality improvement. Portions of this presentation were adapted from Reducing Imperviousness, NEMO Project, University of Connecticut Cooperative Extension System and Introduction to the Eight Tools of Watershed Protection, Center for Watershed Protection, Strategies for Coping with Polluted Runoff 1

2 Nonpoint Education for Municipal Officials NEMO is an educational program for land use decision makers addressing the relationship between land use and water resource protection. NEMO stands for Nonpoint Education for Municipal Officials. Strategies for Coping with Polluted Runoff 2

3 What we ll be covering: Existing Existing and ongoing efforts to improve storm water quality Strategies for coping with polluted runoff Low Low Impact Development (LID) techniques Strategies for Coping with Polluted Runoff 3

4 Interagency Coordination Public Education & Outreach Illicit Discharge Detection & Elimination Storm Water Monitoring Construction Program Industrial Program Municipal Operations Structural Controls Land Use Planning Reno, Sparks and Washoe County are jointly permitted under a National Pollutant Discharge Elimination System (NPDES) permit issued by Nevada Division of Environmental Protection (NDEP) to discharge storm water to the Truckee River. The NPDES permit issued in 2000 and updated in 2005 requires the agencies to develop, implement and enforce a storm water management program that includes each of the nine elements noted above. The Truckee Meadows Regional Stormwater Quality Management Program is a multi-objective program designed to reduce the discharge of pollutants to local streams and the Truckee River. The agencies have an interlocal agreement and share the costs of developing, implementing and enforcing the required elements of the permit. Strategies for Coping with Polluted Runoff 4

5 Public education & outreach C. Conway Local public outreach and education efforts include the regional program Web site ( participation in activities such as Earth Day, Reno Clean and Green, and NEMO, and organization of volunteer storm drain stenciling projects. Additional efforts are being planned, including a partnership with a local TV weather personality to educate the public about storm water pollution and strategies homeowners can use to minimize impacts to local water resources. Strategies for Coping with Polluted Runoff 5

6 Finding and eliminating sources of illicit discharge Stormwater discharge monitoring Dry Weather Flows - Record Street Outfall - Reno C. Conway Several of the main tributaries to the Truckee River are being monitored for storm water pollutants. The picture on the right shows a discharge to the river during a dry summer day. There are several sources for the discharge: groundwater base flow, over-watered landscaped areas, car and street washing, etc. Dry weather flows are also regulated under the NPDES storm water permit and often transport significant pollutant loads. Strategies for Coping with Polluted Runoff 6

7 Construction & Industrial BMPs Slope tracking US 395, Carson City Erosion and sediment controls Inlet protection Industrial site tire wash C. Conway Anyone who has visited a construction site recently has probably noticed erosion and sediment control best management practices (BMPs) such as these. They are the result of the construction element of the Regional Storm Water Program. The industrial element of the regional program includes inspection of industrial sites to ensure that pollutants that could potentially come in contact with storm water are covered and properly stored. It also includes the installation and maintenance of BMPs such as tire washes to prevent the tracking of sediment and debris onto public roadways. Strategies for Coping with Polluted Runoff 7

8 Municipal operations Structural controls Catch basin cleaning - Reno Sand filter detention basin Denver, Colorado C. Conway Reno, Sparks and Washoe County are considering increased cleaning of the storm drain system and municipal streets. New vacuum-type street sweepers improve air quality while reducing storm water pollutants. Structural controls including the sand filter detention basin in Denver, Colorado treat large impervious areas such as parking lots prior to discharge to the storm drain system. The cities and county are developing policies and procedures for the implementation of structural controls for new development and significant redevelopment (an NPDES permit requirement). Strategies for Coping with Polluted Runoff 8

9 Construction Site BMP Handbook Structural Controls Design Manual These manuals can be purchased at the Community Development Departments of Reno, Sparks and Washoe County. They can also be downloaded from the regional program Web site, Strategies for Coping with Polluted Runoff 9

10 Land use planning element R. Arendt Center for Watershed Protection Low Impact Development Center for Watershed Protection Cluster development Bioretention Porous pavement This slide demonstrates three land use planning techniques that are being used throughout the country to reduce the quantity and improve the quality of runoff. These alternative drainage or storm water management techniques are commonly referred to as Low Impact Development (LID) design practices. Strategies for Coping with Polluted Runoff 10

11 Related Groups and Programs Watershed Management and Protection Plan for Tributaries to the Truckee River (2003) Nevada Division of Environmental Protection (NDEP) Regional Water Planning Commission (RWPC) University of Nevada Cooperative Extension (UNCE) Truckee Meadows Water Authority (TMWA) Washoe-Storey Conservation District Floodplain Management & Flood Storage Volume Mitigation Washoe County District Health Department Vector Controls There are many concurrent efforts actively working on water quantity and quality issues in the Truckee Meadows. The Watershed Management and Protection Plan targets stream reaches that are currently at risk. A watershed facilitator has been hired to begin plan implementation. As part of this effort, a Low Impact Development (LID) handbook will also be developed to provide education and design guidance for developers, engineers and planners. NDEP is the primary regulatory agency. They issue storm water discharge permits and manage a number of programs including the wellhead protection program and the NPS program. The RWPC has provided the majority of funding for regional water quantity- and water quality-related projects. The University of Nevada Cooperative Extension continues to provide a wide array of public education and outreach programs to the community, including the NEMO Nevada program. The Washoe-Storey Conservation District is actively involved in projects such as the restoration of Steamboat Creek, and the Floodplain Management and Flood Storage Volume Mitigation group is developing policies to reduce future flooding potentials from new development. The Washoe County District Health Department is actively involved in the control of mosquitoes and the spread of vector-borne diseases such as West Nile Virus. Strategies for Coping with Polluted Runoff 11

12 What does the 2002 Truckee Meadows Regional Plan require? A regional approach to watershed, wastewater and storm water management to ensure state water quality standards are met The identification of sustainable regional water resources and the promotion of development patterns and practices that promote sustainable water use Local government master plans to encourage land uses that promote the responsible management of the region s s water resources The goals of the NEMO Nevada program coincide with the requirements of the 2002 Truckee Meadows Regional Plan. See the plan for more information. Strategies for Coping with Polluted Runoff 12

13 What practices do current ordinances support? Buffer ordinances Groundwater recharge Preserving existing vegetation Open space standards Successful water quality protection can only be accomplished if necessary elements are supported by local ordinances. Below are a few of the ordinances already on the books in Washoe County that improve water quality and reduce NPS: Buffer ordinances Groundwater recharge Preserving existing vegetation Open space standards Strategies for Coping with Polluted Runoff 13

14 Preserve and enhance buffers S. Donaldson S. Donaldson Buffer Ordinances: Washoe County has ordinances protecting perennial stream buffer areas (section Significant Hydrologic Resources). Perennial stream buffer areas are established to provide adequate setbacks and land use controls to ensure water quality functions of each perennial stream are not jeopardized through development activity. To limit significant impacts adjacent to hydrologic resources, two buffer areas have been established. All proposals to develop uses within these two buffer zones are required to submit site plans with precise dimensions depicting the boundary line for the buffer area. The two buffer zones are defined as follows: (a) Critical Stream Zone Buffer Area: The critical stream zone buffer area shall be all land and water surface within thirty (30) feet from the centerline of the perennial stream. (b) Sensitive Stream Zone Buffer Area: The sensitive stream zone buffer area shall be all land and water surface between the critical stream zone buffer area boundary of thirty (30) feet and one hundred fifty (150) feet from the centerline of the perennial stream. No development or extremely limited uses are allowed in these two buffer zones. Fences deterring livestock are allowed, upon approval. Special use permits detailing protective BMPs are required for more intensive land uses. Strategies for Coping with Polluted Runoff 14

15 Groundwater Recharge Encourage groundwater recharge J Stone This detention or retention basin holds storm water runoff and allows for groundwater recharge. Additionally, natural processing of some pollutants occurs by interaction with the vegetation and soil. Article 412 of the Washoe County Development Code supports these types of facilities. Article 412 (ord 867), Section , provisions effective 5/27/93. Landscaping Water Conservation. To promote resource-efficient landscaping for the conservation of water and other natural resources, the following principles and practices are encouraged: (e) The installation of permeable hard surfaces to encourage groundwater recharge and reuse and discourage run-off. (f) The use of water harvesting techniques. (g) The use of mulches. Article 412 (ord 867), Section , Landscaping General Requirements (d) Erosion Control: Erosion shall be controlled by slowing storm water runoff and assisting in groundwater recharge. (e) Storm Water Runoff shall be minimized in landscaped areas (1) Storm water detention/retention basins not integrated with paved areas shall be landscaped to enhance the natural configuration of the basin and plants located within the lower one-third portion of the basin must withstand periodic submersion. Strategies for Coping with Polluted Runoff 15

16 Preserve existing vegetation C. Conway Article 412 (ord 867), Section , provisions effective 5/27/93. Landscaping Existing Vegetation. Existing vegetation within the total developed land area,, shall be preserved as set forth in this section and may contribute toward all landscaping required by this article, including: (a) Existing Vegetation: Existing vegetation and ecological communities shall be protected and preserved where appropriate and feasible; (b) Preservation of Protected and Endangered Vegetation: Protected and endangered vegetation as defined in the Conservation Element of the Washoe County Comprehensive Plan; and (c) Preservation of Significant Trees: Existing trees with a caliper greater than six (6) inches, as measured 54 inches from grade, shall be preserved if feasible. Protection measures, including nondisturbance around drip-line and/or root zone, shall be incorporated into the landscaping plan. Article 412 (ord 867), Sections , provisions effective 5/27/93. Landscaping Landscape Coverage Requirements. Residential Use Types: A minimum of twenty (20) percent of the developed land area shall be landscaped. Civic and Commercial Use Types: A minimum of twenty (20) percent of the total developed land area shall be landscaped. Industrial and Agricultural Use Types: A minimum of ten (10) percent of the total developed land area shall be landscaped. Any disturbance to undeveloped portions of the site shall be mitigated. All of above can be natural undisturbed vegetation. Parking and Loading Areas: At least one (1) tree shall be provided for every ten (10) parking spaces, provided the distance between trees does not exceed twelve (12) spaces in a row and the trees are evenly distributed throughout the paved area. Strategies for Coping with Polluted Runoff 16

17 Develop open space standards NRCS Photo Gallery (This photo is from Colorado.) Article 408 (ord 876), Section , provisions effective 7/7/93. Common Open Space Development - Roads To the extent possible, common roads and driveways shall be used for access. The roads shall be aligned to follow natural features and topography where possible. Article 408 (ord 876), Section , provisions effective 7/7/93. Common Open Space Development Conditions of Approval Common Open Space development is required to have a three-year maintenance plan. Plan must address vegetation management, watershed management, debris/litter removal, fire suppression, maintenance of public access, and anything else deemed necessary by the Planning Commission. Provisions for permanent preservation and maintenance are supposed to be made, but the language is vague as to the method. Article 432 (ord 949), Sections , provisions effective 5/1/96. Open Space Standards Purpose The intent of these regulations is to protect the public health, safety and welfare by: (c) Encouraging open space buffers and greenbelt areas to help define boundaries between development areas, communities or neighborhoods so that all development does not run together in a suburban sprawl pattern; and (d) Protecting environmentally sensitive habitat. Strategies for Coping with Polluted Runoff 17

18 Plan What can you and your community do? Plan development based on your community s s natural resources Minimize Minimize impacts through site design, source control and public education Mitigate Mitigate unavoidable impacts by using best management practices (BMPs) Strategies for Coping with Polluted Runoff 18

19 Existing natural resource inventory Soil permeability Tributary watersheds Washoe County Water Resources Washoe County Water Resources We can use the existing natural resource inventory data currently available to help identify locations at risk to significant water quality impacts from development. Both paper and digital information exists that identifies soils with good recharge potential, stream corridors, wetlands, high value open space, critical wildlife habitat, current and planned land uses and many other attributes. Strategies for Coping with Polluted Runoff 19

20 What about the land use planning element? Low Impact Development (LID) Conventional storm water management seeks to remove water from the site as quickly and efficiently as possible LID works with nature to help protect sensitive areas (streams, wetlands) by preserving the natural flow patterns and volume of runoff LID seeks to mimic natural hydrologic functions by using site design techniques to store, infiltrate, evaporate, and detain runoff LID practices are built upon a premise agreed upon by many storm water managers: control storm water close to the source (where it originates) and keep pollutants out of the storm drain system and receiving waters. This is accomplished by protecting native vegetation, reducing the amount of hard surfaces and compaction of soil, treating storm water runoff close to where it starts, and slowing the flow of storm water runoff so that the quantity and quality of runoff is similar to what it was prior to the site being developed. LID is one of several new urban planning techniques. It differs from other techniques such as Smart Growth and Sustainable Development in that LID is primarily focused on alternative storm water management techniques. Smart Growth is a term that describes the efforts of communities across the United States to manage and direct growth in a way that minimizes damage to the environment and builds livable towns and cities. Smart Growth addresses problems caused by sprawl by emphasizing the concept of developing "livable" cities and towns. Sustainable development is a new term that grew out of the conservation/environmental movement of the 1970's. A sustainable community preserves and enhances the quality of life of residents both within and between communities, while minimizing local impacts on the natural environment. Strategies for Coping with Polluted Runoff 20

21 Puget Sound Action Team Small scale storm water controls largely consist of different landscaping and drainage techniques that function to capture and treat or infiltrate runoff. Customized site designs help to preserve natural drainage areas and valuable open space. Regular maintenance of LID design techniques and public education about pollution prevention measures helps the public gain a sense of stewardship of watersheds and streams. These techniques also help to conserve water and increase groundwater recharge. Strategies for Coping with Polluted Runoff 21

22 Common LID practices Open space and cluster development Reduced amount of impervious surfaces Disconnected impervious surfaces Convey roof runoff to vegetated areas Reduce and treat runoff with Filtration buffers and swales Bioretention features Extended detention/retention basins Infiltration features Permeable pavements The following slides provide examples of these common LID Practices. For more information, the draft LID manual for the Truckee Meadows can be downloaded at Strategies for Coping with Polluted Runoff 22

23 PEOPLE & PAVEMENT A close but evolving relationship Human sacrifice Impervious surface coverage increases with urbanization. Car habitat UCONN Coop. Ext. NEMO Throughout history, people have created large impervious structures. Where once they were created as altars to pagan gods for human sacrifice, we are now creating immense impervious structures and sacrificing our natural resources. Is history repeating itself? Strategies for Coping with Polluted Runoff 23

24 Conventional development NRCS photo gall This is an aerial view of conventional development in Las Vegas. Note the high percentage of impervious surfaces, the lack of open space, the wide streets and the prominent cul-de-sacs. This type of development has the potential to increase runoff by as much as 60 percent to 75 percent. Strategies for Coping with Polluted Runoff 24

25 An alternate planning approach: Open Space and Cluster Development Same number of housing units 10-50% less impervious surface Increased resale value Up to 50% open space Water resources protected From Randall Arendt It s important to note that open space should not be limited to the low value, nondevelopable portion of the development. To provide multiple benefits to water quality, habitat, recreation, and aesthetics, open space should consist of continuous, contiguous, high-value land, preferably in an undisturbed condition, with the native vegetation left intact. Planning for maintenance is essential, and should include the following factors: Who is responsible for performing regular maintenance, including weed control and other vegetation management? Who will pay for maintenance? What mechanisms must be in place to ensure maintenance is properly performed? Strategies for Coping with Polluted Runoff 25

26 This example of an open space design utilizes the existing character of the area by minimizing clearing and grading and preserving large tracts of natural open space. C. Conway The large amount of unnecessary impervious cover and clearing of natural areas associated with conventional development can be reduced significantly by changing the shape, orientation, and layout of residential lots. This development has relatively small lot sizes within a compact, developed portion of the property while leaving the remaining portion open. Grading and filling have been reduced, and natural features preserved. The aerial photograph shows a local example from the ArrowCreek development in southwest Reno. Homes constructed in developments such as this are highly sought after and typically have greater resale values than homes in conventional developments. Strategies for Coping with Polluted Runoff 26

27 Questions to ask about site design when reviewing plans: Does the design allow impervious surfaces to be minimized and/or disconnected? Does the design maintain high-value open space in an undisturbed condition, or is it limited to non-developable, low-value land? Are natural features preserved? Are grading and filling minimized? Are creeks and waterways buffered and protected from disturbance? When you are reviewing plans, consider asking the questions listed above that apply to the specific situation. Strategies for Coping with Polluted Runoff 27

28 S. Donaldson Typical cul-de de- sacs are often large enough to double as spaceship landing pads. This conventional cul-de-sac design will result in a significant increase in the amount of runoff in this development. The curb and gutter system will ensure that the additional runoff will flow directly to the storm drain system and into nearby streams, rivers and lakes without treatment, polluting the water. Strategies for Coping with Polluted Runoff 28

29 Is all that pavement necessary? Narrow streets instead of a wide cul-de de- sac Shorter driveways Center for Watershed Protection Shared green space in center of street There are a number of ways to reduce pavement, including alternative-sized streets, shorter or partially paved driveways, and the addition of green spaces or infiltration areas in the center of streets or cul-de-sacs. A reduction of pavement means less impervious cover, more infiltration, and more filtration of pollutants. Strategies for Coping with Polluted Runoff 29

30 12 10 Typical streets are often excessively wide, increasing traffic speeds and making streets unfriendly to pedestrians. Accidents/Mile/Year Street Width (ft) Photo Copyright 1999, Center for Watershed Protection Typical streets are often excessively wide, increasing traffic speeds and the number of accidents. They also make streets unfriendly to pedestrians and dangerous for children. The graph shows that generally, as street widths increase, the number of accidents per year also increases. Strategies for Coping with Polluted Runoff 30

31 Pavement width can be much less than the right-of of-way Shoulder/swale= 12 Pavement = 24 R.O.W. = 48 Subbase UCONN Coop. Ext. NEMO In areas where wider streets are needed for emergency vehicle access, or to preserve right-of-way, consider paving only a portion of the street, and building drivable swales on each side of the road. Strategies for Coping with Polluted Runoff 31

32 Parking lots are often underutilized and can be minimized through better site design techniques. Photo Copyright 1999, Center for Watershed Protection Parking lots are a major source of pollutants in storm water runoff and are often underutilized. Approximately 65 percent of total impervious cover in the urban landscape is "habitat for cars," in the form of parking lots, roads, and driveways. Much of this impervious cover is often unnecessary and can be minimized at every stage of parking lot and residential street planning and design. RTC is presently investigating parking space requirements. Strategies for Coping with Polluted Runoff 32

33 Alternatives to impervious pavement Not less engineering......different engineering! UCONN Coop. Ext. NEMO Much research currently focuses on alternatives to impervious pavement, from porous concrete and asphalt, to pervious pavers. Strategies for Coping with Polluted Runoff 33

34 Pervious alternatives cost factors: grid systems Grid systems Short Term: ~20% more expensive (for now) Long Term: Modular systems cheaper (less drainage piping) UCONN Coop. Ext. NEMO When costly underground infrastructure can be avoided, pervious alternatives can be reasonably priced. Strategies for Coping with Polluted Runoff 34

35 Porous pavement Provides pollutant removal by filtration and biochemical reactions Underlain by sand, porous pavement effectively removes pollutants by filtration and biochemical reactions. The benefits include less winter heaving. Porous pavement has been used extensively in Europe on roadways, parking lots and loading docks. Strategies for Coping with Polluted Runoff 35

36 Questions to ask about pavement: Is all the pavement necessary? (Can the design incorporate fewer sidewalks, shorter driveways, narrower streets, etc.) Can alternative porous paving materials be used for at least some of the pavement? Has space for infiltration and/or bioretention been incorporated into cul-de de-sacs? Can parking lots incorporate pervious pavement into rarely-used spaces? Strategies for Coping with Polluted Runoff 36

37 UCONN Coop. Ext. NEMO Landscape detention/ bioretention Center for Watershed Protection C. Conway Not limited to parking lots, bioretention can be used for rain water infiltration in any landscape setting. Bioretention is actually a form of water harvesting. If properly designed, constructed and maintained, bioretention practices can significantly reduce runoff and are very effective at removing pollutants from storm water. Strategies for Coping with Polluted Runoff 37

38 Onsite landscape detention C. Conway Source: Center for Watershed Protection Use of bioretention structures such as the one shown in the diagram above can reduce or eliminate the need to install costly underground storm drain infrastructure. The photo shows a new development in northwest Reno that has the potential to be an LID design. If the gravel and shrub section had been over-excavated and engineered soils added, it could have been used to retain all of the runoff produced by one or two homes, thereby saving the developer money by reducing or eliminating the need for a conventional underground storm drain system. Per District Health Vector Control Standards, the system must be designed to drain and prevent ponding and breeding of mosquitoes. The ponded area shown in the diagram depicts the designed maximum ponding depth, typically 6 to 8 inches, before water spills into an overflow pipe or a swale. Strategies for Coping with Polluted Runoff 38

39 Parking design UCONN Coop. Ext. NEMO Parking islands can be used for bioretention S. Donaldson UCONN Coop. Ext. NEMO A review of city and county codes indicates that these structures are allowed in the Truckee Meadows. Biorention islands can be installed without curbs, or may allow runoff to enter via curb cuts. Strategies for Coping with Polluted Runoff 39

40 Bioretention cell Center for Watershed Protection This parking lot bioretention cell is surrounded by special wheel stops that allow runoff to flow under them. The gaps in the concrete wheel stops also help to break up the velocity of runoff entering the depressed bioretention area. Strategies for Coping with Polluted Runoff 40

41 Landscape buffers for lawns C. Conway C. Conway It s not uncommon to see lawns extending all the way to the edge of the curb or sidewalk in the Truckee Meadows. These areas are almost impossible to irrigate without overspray and runoff onto sidewalks and streets. At both new and old developments, a significant amount of runoff in the storm drain system is the result of over-watering or overspray from lawn irrigation systems. During the summer months, strong afternoon winds often blow a significant amount of sprinkler system water onto the streets. People that water their lawns in the afternoon on a hot summer day when the wind is blowing can lose as much as 40% of the water to runoff and evaporation. Homeowners can easily install rock buffers with xeriscape landscaping to reduce runoff from lawn watering systems. When designing these types of buffers, additional retention and treatment of runoff can be obtained by over-excavating buffer areas and adding engineered soils. Economic incentives for the removal of turf and the installation of buffers and xeriscape gardens should be considered for both water conservation purposes and storm water quality improvement. For example, communities such as Las Vegas are paying homeowners one dollar for each square foot of lawn removed to assist with the cost of installing xeriscape gardens. Strategies for Coping with Polluted Runoff 41

42 Prince Georges County, MA This table provides bioretention design guidance from Prince Georges County, MA. The new design standards in the right column, provided in the 2002 revised document, are being tested by Caltrans in California to treat highway and freeway runoff. The new design is only 3.5 feet deep and does not include a separate sand layer. This design has been shown to be less prone to clogging. Important features include an under-drain pipe system for areas with soils that have poor infiltration characteristics. These systems must be designed to drain within seven days to prevent mosquito breeding. They must also include an overflow system that consists of either a pipe or a weir that conveys flows to the storm drain system, to a swale, or to a natural drainage. Strategies for Coping with Polluted Runoff 42

43 Landscape filtration systems C. Conway New development Retrofitting existing development This particular LID design is well-suited for retrofitting existing developments. The cartoon at the lower right demonstrates how runoff from the most frequently occurring small storm events as well as nuisance flows from over- watering and washing activities can be captured and treated by a specially- designed planter box. Again, this is another form of water harvesting that helps to both conserve water and improve water quality. To get a better idea of how this system works, go to: There are many innovative proprietary structural controls that have been recently developed and are being tested around the nation. The Structural Controls Design Manual provides an overview of the various types of proprietary or manufactured structural controls currently available, as well as the numerous public domain structural controls that can be designed and constructed by an engineer. The manual is available at Strategies for Coping with Polluted Runoff 43

44 Infiltration trench Runoff Center for Watershed Protection In this example, runoff flows out of the parking lot through curb cuts and into a grass-lined swale before entering the infiltration trench. The grassy swale acts to pre-treat the runoff and remove some of the sediment that might clog the trench. Infiltration trench design notes: Soil type must permit infiltration Helps to recharge groundwater Only applicable in certain areas Longevity is typically reduced without pretreatment of the runoff Should not be used if contributing drainage is a hotspot (i.e. an industrial site) Strategies for Coping with Polluted Runoff 44

45 Questions to ask about bioretention: Can parking lot islands be used to absorb runoff, rainwater and snowmelt? Have overflow structures been included in the design of bioretention basins? Are buffers provided at residential lawn/pavement perimeters? Are soil types appropriate to permit storm water infiltration? Strategies for Coping with Polluted Runoff 45

46 Impervious cover reduction Several techniques can be incorporated into a parking lot design to protect water quality, including providing compact car spaces, utilizing alternative paving materials in overflow parking, and treating storm water with the use of bioretention areas. Strategies for Coping with Polluted Runoff 461

47 Open channel practices vegetated swales C. Conway This is a photo of a dry swale on Kietzke Lane just south of Lowes. The term vegetated swale refers to open channel management practices designed specifically to treat and attenuate storm water runoff for a specified water quality volume. As storm water runoff flows through these channels, it is treated through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Swales work well for treating highway or residential road runoff because they are linear practices. Dry swales are similar in design to bioretention areas. These designs incorporate a fabricated soil bed into their design. That is, the existing soil is replaced with a sand/soil mix that meets minimum permeability requirements. An underdrain system is used under the soil bed. This system consists of a gravel layer that encases a perforated pipe. Stormwater treated in the soil bed flows through the bottom into the underdrain, which conveys the treated storm water to the storm drain system. The swale is designed to rapidly dewater, which makes this practice a good choice for low-density residential projects or for very small impervious areas. Strategies for Coping with Polluted Runoff 47

48 Open channel practices engineered swales Kietzke Lane, Reno C. Conway This is an example of a grass-lined swale that could potentially have been an LID design if it had been over-excavated, filled with engineered soils, and an underdrain installed to promote filtration and infiltration of storm water and prevent standing water. Dry swale design notes: High space requirements May require supplementary irrigation Swale has engineered soil matrix Ideal for open section roads and low density residential streets Strategies for Coping with Polluted Runoff 48

49 Cost factors Traditional Drainage $150 - $250 per linear foot Engineered Swales $10 - $25 per linear foot Don t forget, Maintenance Includes: Inspection Sediment/debris removal Structural repairs Who will Maintain? Curbing Catch basins Piping Outlet Structure Detention/Retention Ponds UCONN Coop. Ext. NEMO Engineered swales can provide significant cost savings over traditional designs. Maintenance (mowing) in residential areas is typically performed by the homeowner. Strategies for Coping with Polluted Runoff 49

50 Questions to ask about swales: Can swales be used to convey and treat storm water runoff instead of curbs & gutters? Does the swale design include an engineered soil matrix that will dewater rapidly? Can supplemental irrigation be provided, as needed, to maintain vegetation? Can native vegetation be used instead of turf? Who will maintain the swales? Strategies for Coping with Polluted Runoff 50

51 Detention basins C. Conway C. Conway Required for flood control Often not maintained properly Provide minimal water quality benefits Can breed vectors These are two examples of local detention basins. They often become eyesores when not maintained, and can breed mosquitoes. The upper right photo shows a poorly-designed detention basin located near Whites Creek in southwest Reno. The steep slopes and lack of vegetation will likely lead to erosion and sediment transport to Whites Creek. The ponded area may provide habitat for mosquito and midge breeding. The lower left photo is from a development in the northwest near Rancho San Rafael Park. If onsite LID design techniques had been implemented, these areas might have become available as open space, a park or an additional house. Strategies for Coping with Polluted Runoff 51

52 Residential roof drainage Residential roof water is relatively clean, and can be easily taken out of the storm water loop. Redirect down spouts to pervious areas, rain gardens, or rain barrels UCONN Coop. Ext. NEMO Many new developments have downspouts that direct runoff to vegetated areas. However, many older homes continue to direct roof runoff onto paved areas that drain directly to the street or a storm drain. Since roof runoff is typically better quality water than the municipal water supply that is treated with chlorine, it can be stored in rain barrels and used to water sensitive plants. Strategies for Coping with Polluted Runoff 52

53 Commercial roof drainage C. Conway S. Donaldson Sparks Library US Bank building, McCarran & Neil Rd., Reno Commercial areas often pipe roof runoff directly onto other impervious surfaces and then direct it towards curbs and gutters that convey it into storm drain as quickly as possible. A better alternative is to convey roof drainage to vegetated areas, bioretention structures or infiltration facilities. With the large number of warehouses and large department stores in the Truckee Meadows, commercial roof runoff provides a significant contribution to the area s storm drain system. Strategies for Coping with Polluted Runoff 53

54 C. Conway Multifamily developments, such as the Enclave in southeast Reno, can mitigate impacts by slowing and filtering storm water runoff across common areas, avoiding direct connections to the storm drain system, providing regular maintenance to remove trash and spills, and providing education to tenants to remove pet waste. Strategies for Coping with Polluted Runoff 54

55 This conceptual plan utilizes several better site design techniques, including a vegetated island that allows storm water filtration, shorter driveways, narrow streets, and alternate pavement for overflow parking. This conceptual plan utilizes several better site design techniques, including a vegetated island that allows storm water filtration, shorter driveways, narrow streets, and alternate pavement for overflow parking. Strategies for Coping with Polluted Runoff 55

56 Other questions to ask: Is there a plan for phased development and clearing to minimize soil disturbance? Are drainage flow paths as long as possible, to encourage infiltration? Are impervious surfaces minimized or disconnected with vegetated buffers? Have pervious alternatives been considered for RV and overflow parking areas? Have bioretention or infiltration features been incorporated into the landscaping plan? Strategies for Coping with Polluted Runoff 56

57 Getting started with LID 1. Form a Professional Advisory Group 2. Identify development categories 3. Permitting and plan review procedures 4. Standard design criteria 5. Construction inspection procedures 6. Determine responsibility for long-term operation and maintenance To successfully incorporate LID into a proposed project, LID design features must be considered during each phase of development process. Applicable zoning, land use, and other local regulations that support the use of LID must be developed and enforced. Efforts are currently underway to define existing codes and ordinances that support LID practices, and those that might conflict. Local policies and procedures are also being developed, along with an LID manual (see These policies and procedures will require that the development envelope is properly defined such that buffers, setbacks and overlay zones are defined during the concept phase of the project and valuable resources such as wetlands, streams, drainage ways and recharge areas are protected. The design should strive to reduce or minimize total site impervious cover as well as minimize directly-connected impervious surfaces. Strategies for Coping with Polluted Runoff 57

58 Getting started with LID 7. Develop applicable zoning and land use regulations 8. Training for developers, architects, contractors and agency staff 9. Incorporate LID practices into site designs 10. Develop long-term operation and maintenance plans 11. Inspection and enforcement Integrated Management Practices (IMPs) such as bioretention areas, infiltration structures and vegetated swales should be included on site plans and reviewed for feasibility. If infiltration structures are proposed, infiltration tests of the soils must be conducted to confirm infiltration rates. Runoff flow paths should be maximized to increase potential for infiltration and water treatment. A comparison of pre- and post-development hydrology must be conducted to determine whether runoff will increase and which mitigation measures will be necessary to treat increased flows and pollutant loads. The ultimate goal of LID is to create developments that mimic pre-development hydrology and do not increase runoff. This may require an iterative process to achieve the desired end result. Finally, an effective long-term operation and maintenance plan is imperative. It must be transferable from one property owner to the next and enforceable by the local agency. Without proper maintenance, structural controls and LID practices will fail and cease to function as designed. This important element is also being researched and developed. Strategies for Coping with Polluted Runoff 58

59 Any questions?? Strategies for Coping with Polluted Runoff 59

60 NEMO, Nonpoint Education for Municipal Officials, is an educational program for land use decision makers addressing the relationship between land use and water resource protection. COOPERATIVE EXTENSION Bringing the University to You Strategies for Coping with Polluted Runoff 60