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Strategies for Coping with Polluted Runoff 1

Strategies for Coping with Strategies for Coping with Polluted RunoffPolluted Runoff

Cooperative ExtensionBringing the University to You

Audiovisual-05-15

C. Conway

Strategies for Coping with Polluted Runoff

Chris ConwayKennedy Jenks Consultants

Susan DonaldsonMelody HefnerUniversity of Nevada Cooperative Extension Audiovisual-05-15

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 rock-lined 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, 1999.


NNonpoint onpoint EEducation for ducation for MMunicipal unicipal OOfficialsfficials

NEMONEMO is an educational program for is an educational program for land use decision makers addressing the land use decision makers addressing the relationship between land use and water relationship between land use and water

resource protection.resource protection.

NEMO stands for “Nonpoint Education for Municipal Officials.”


Existing and ongoing efforts to Existing and ongoing efforts to improve storm water qualityimprove storm water quality

Strategies for coping with Strategies for coping with polluted runoffpolluted runoff

Low Impact Development (LID) Low Impact Development (LID) techniquestechniques

What weWhat we’’ll be covering:ll be covering:


Public Education &

Outreach

Storm WaterMonitoring

ConstructionProgram

InteragencyCoordination

IndustrialProgram

Land UsePlanning

StructuralControls

MunicipalOperations

Illicit DischargeDetection & Elimination

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.


Public education & outreachPublic education & outreach

www.TMstormwater.comwww.TMstormwater.com

C. Conway

Local public outreach and education efforts include the regional program Web site (www.TMstormwater.com), 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.


Finding and Finding and eliminating sources of eliminating sources of

illicit dischargeillicit discharge

Dry Weather Flows - Record Street Outfall - Reno

Stormwater Stormwater discharge discharge monitoringmonitoring

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.


Construction & Industrial BMPsConstruction & Industrial BMPs

•• Erosion and sediment Erosion and sediment controlscontrols

•• Inlet protectionInlet protection

•• Industrial site tire washIndustrial site tire wash

Slope tracking Slope tracking –– US 395, US 395, Carson CityCarson City

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.


Municipal operationsMunicipal operations

Structural controlsStructural 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).


www.TMstormwater.comwww.TMstormwater.com

Construction Site Construction Site BMP HandbookBMP Handbook

Structural ControlsStructural ControlsDesign ManualDesign 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, www.TMstormwater.com


Land use planning elementLand use planning element

Low Impact DevelopmentLow Impact Development

Cluster developmentCluster developmentBioretentionBioretentionPorous pavementPorous pavement

R. Arendt

Center for Watershed Protection


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.


Related Groups and ProgramsWatershed 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 DistrictFloodplain Management & Flood Storage Volume MitigationWashoe 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.


What does the 2002 Truckee What does the 2002 Truckee Meadows Regional Plan require?Meadows Regional Plan require?

A A regional approachregional approach to watershed, wastewater and to watershed, wastewater and storm water management to ensure state water quality storm water management to ensure state water quality standards are metstandards are met

The identification of The identification of sustainable regional water sustainable regional water resourcesresources and the promotion of development patterns and the promotion of development patterns and practices that promote sustainable water useand practices that promote sustainable water use

Local government master plans to encourage land uses Local government master plans to encourage land uses that promote the that promote the responsible management of the responsible management of the regionregion’’s water resourcess 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.


What practices do current What practices do current ordinances support?ordinances support?

Buffer ordinancesBuffer ordinancesGroundwater rechargeGroundwater rechargePreserving existing vegetationPreserving existing vegetationOpen space standardsOpen 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


Preserve and

enhance buffers

S. Donaldson

S. Donaldson

Buffer Ordinances:Washoe County has ordinances protecting perennial stream buffer areas (section 110.418.15 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.


Groundwater RechargeGroundwater Recharge

Encourage groundwater rechargeEncourage 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 110.412.20, 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 re-use and discourage run-off.

(f) The use of water harvesting techniques.(g) The use of mulches.Article 412 (ord 867), Section 110.412.70, 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.


Preserve existing vegetationPreserve existing vegetation

C. Conway

Article 412 (ord 867), Section 110.412.25, 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 non-disturbance around drip-line and/or root zone, shall be incorporated into the landscaping plan.Article 412 (ord 867), Sections 110.412.35-.50, 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.


Develop open space standardsDevelop open space standards

NRCS Photo Gallery

(This photo is from Colorado.)Article 408 (ord 876), Section 110.408.35, provisions effective 7/7/93. Common Open Space Development - RoadsTo 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 110.408.45, provisions effective 7/7/93. Common Open Space Development – Conditions of ApprovalCommon 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 110.432, provisions effective 5/1/96. Open Space Standards – PurposeThe 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.


What can you and your What can you and your community do?community do?

Plan Plan development based on your development based on your communitycommunity’’s natural resourcess natural resources

MinimizeMinimize impacts through site design, impacts through site design, source control and public educationsource control and public education

MitigateMitigate unavoidable impacts by using unavoidable impacts by using best management practices (BMPs)best management practices (BMPs)


Existing natural resource inventoryExisting 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.


What about the land use What about the land use planning element?planning element?

Low Impact Development (LID)Low Impact Development (LID)Conventional storm water management seeks to Conventional storm water management seeks to remove water from the site as quickly and remove water from the site as quickly and efficiently as possibleefficiently as possible

LID works with nature to help protect sensitive LID works with nature to help protect sensitive areas (streams, wetlands) by preserving the areas (streams, wetlands) by preserving the natural flow patterns and volume of runoffnatural flow patterns and volume of runoff

LID seeks to mimic natural hydrologicLID seeks to mimic natural hydrologic functions functions by using site design techniques to store, infiltrate, by using site design techniques to store, infiltrate, evaporate, and detain runoffevaporate, 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.


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.


Common LID practicesCommon LID practicesOpen space and cluster developmentOpen space and cluster developmentReduced amount of impervious surfacesReduced amount of impervious surfacesDisconnected impervious surfacesDisconnected impervious surfacesConvey roof runoff to vegetated areasConvey roof runoff to vegetated areasReduce and treat runoff withReduce and treat runoff with–– Filtration buffers and swalesFiltration buffers and swales–– Bioretention featuresBioretention features–– Extended detention/retention basinsExtended detention/retention basins–– Infiltration featuresInfiltration features–– Permeable pavementsPermeable 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 www.TMstormwater.com


PEOPLE & PAVEMENTPEOPLE & PAVEMENTA close but evolving relationshipA close but evolving relationship

Impervious surface Impervious surface coverage increases with coverage increases with

urbanization.urbanization.

Human sacrificeHuman sacrifice

Car habitatCar 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?


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.


An alternate planning approach:An alternate planning approach:Open Space and Cluster DevelopmentOpen Space and Cluster Development

From Randall ArendtFrom Randall Arendt

• Same number of housing units

• 10-50% less impervious surface

• Increased resale value

• Up to 50% open space

• Water resources protected

It’s important to note that “open space” should not be limited to the low value, non-developable 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?


This example of an open space This example of an open space design utilizes the existing design utilizes the existing

character of the area by character of the area by minimizing clearing and grading minimizing clearing and grading

and preserving large tracts of and preserving large tracts of natural open space.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.


Questions to ask about site Questions to ask about site design when reviewing plans:design when reviewing plans:

•• Does the design allow impervious surfaces to be Does the design allow impervious surfaces to be minimized and/or disconnected?minimized and/or disconnected?

•• Does the design maintain highDoes the design maintain high--value open value open space in an undisturbed condition, or is it limited space in an undisturbed condition, or is it limited to nonto non--developable, lowdevelopable, low--value land?value land?

•• Are natural features preserved?Are natural features preserved?

•• Are grading and filling minimized?Are grading and filling minimized?

•• Are creeks and waterways buffered and Are creeks and waterways buffered and protected from disturbance?protected from disturbance?

When you are reviewing plans, consider asking the questions listed above that apply to the specific situation.


Typical culTypical cul--dede--sacs are often sacs are often large enough large enough to double as to double as spaceship spaceship

landing pads.landing pads.S. Donaldson

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.


Is all that pavement necessary?Is all that pavement necessary?

Narrow Narrow streets streets

instead of a instead of a wide culwide cul--dede--

sacsac

Shorter Shorter drivewaysdriveways

Shared green Shared green space in space in center of center of

streetstreetCenter for Watershed Protection

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.


Typical streets are often Typical streets are often excessively wide, excessively wide,

increasing traffic speeds increasing traffic speeds and making streets and making streets

unfriendly to pedestrians.unfriendly to pedestrians.Photo Copyright 1999, Center for Watershed Protection

0

2

4

6

8

10

12

20 22 24 30 32 34 36 38 40 42 44 46 48 50

Street Width (ft)

Acc

iden

ts/M

ile/Y

ear

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.


Pavement = 24’Pavement = 24Pavement = 24’’

R.O.W. = 48’R.O.W. = 48R.O.W. = 48’’

SubbaseSubbaseSubbase

Shoulder/swale= 12’Shoulder/swale= 12Shoulder/swale= 12’’

Pavement width can be Pavement width can be much less than the much less than the

rightright--ofof--wayway


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.


Parking lots are Parking lots are often often

underutilized underutilized and can be and can be minimized minimized

through better through better site design site design techniques.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.


Alternatives to impervious pavementAlternatives to impervious pavementNot less engineering...Not less engineering...Not less engineering...

...different engineering!...different...different engineering!engineering!


Much research currently focuses on alternatives to impervious pavement, from porous concrete and asphalt, to pervious pavers.


Pervious alternatives Pervious alternatives cost factors: grid systems cost factors: grid systems

Short TermShort Term: : ~20% more expensive (for now)~20% more expensive (for now)

Long TermLong Term:: cheaper (less drainage piping)cheaper (less drainage piping)

Grid systems Grid systems Modular systems Modular systems


When costly underground infrastructure can be avoided, pervious alternatives can be reasonably priced.


Porous pavementPorous 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.


Questions to ask about pavement:Questions to ask about pavement:

•• Is all the pavement necessary? (Can the design Is all the pavement necessary? (Can the design incorporate fewer sidewalks, shorter driveways, incorporate fewer sidewalks, shorter driveways, narrower streets, etc.)narrower streets, etc.)

•• Can alternative porous paving materials be used Can alternative porous paving materials be used for at least some of the pavement?for at least some of the pavement?

•• Has space for infiltration and/or Has space for infiltration and/or bioretentionbioretentionbeen incorporated into culbeen incorporated into cul--dede--sacs?sacs?

•• Can parking lots incorporate pervious pavement Can parking lots incorporate pervious pavement into rarelyinto rarely--used spaces?used spaces?


Landscape Landscape detention/ detention/

bioretentionbioretentionUCONN Coop. Ext. NEMO

Center for Watershed ProtectionC. 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.


Source: Center for Watershed Protection

OnsiteOnsitelandscape landscape detentiondetention

C. Conway

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.


Parking islands can be used for bioretention

Parking islands can be used Parking islands can be used for bioretentionfor bioretention

Parking designParking design

S. Donaldson



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.


Bioretention cellBioretention cell


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.


Landscape buffers for lawnsLandscape 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.


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.


Landscape Landscape filtrationfiltrationsystemssystems

New developmentNew developmentRetrofitting existing Retrofitting existing developmentdevelopment

C. Conway

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: http://www.americastusa.com/filterra.htmlThere 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 www.TMstormwater.com.


Infiltration trench

Runoff


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)


Questions to ask about Questions to ask about bioretentionbioretention::

•• Can parking lot islands be used to absorb runoff, Can parking lot islands be used to absorb runoff, rainwater and snowmelt?rainwater and snowmelt?

•• Have overflow structures been included in the Have overflow structures been included in the design of design of bioretentionbioretention basins?basins?

•• Are buffers provided at residential Are buffers provided at residential lawn/pavement perimeters?lawn/pavement perimeters?

•• Are soil types appropriate to permit storm water Are soil types appropriate to permit storm water infiltration?infiltration?


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.


Open channel practices Open channel practices –– vegetated swalesvegetated 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 underdrainsystem 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.


Kietzke Lane, Reno

Open channel practices Open channel practices –– engineered swalesengineered swales

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 underdraininstalled 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


Traditional Drainage $150 - $250 per linear footTraditional Drainage $150 Traditional Drainage $150 -- $250 per linear foot$250 per linear foot

Don’t forget, Maintenance Includes:Don’t forget, Maintenance Includes:

Inspection Sediment/debris removal Structural repairsInspection Sediment/debris removal Structural repairs

Who will Maintain?Who will Maintain?

Engineered Swales $10 - $25 per linear footEngineered Swales $10 Engineered Swales $10 -- $25 per linear foot$25 per linear foot

• Curbing

• Catch basins

• Piping

• Outlet Structure

• Detention/Retention Ponds

• Curbing

• Catch basins

• Piping

• Outlet Structure

• Detention/Retention Ponds

Cost factorsCost factors


Engineered swales can provide significant cost savings over traditional designs. Maintenance (mowing) in residential areas is typically performed by the homeowner.


Questions to ask about swales:Questions to ask about swales:

•• Can swales be used to convey and treat storm Can swales be used to convey and treat storm water runoff instead of curbs & gutters?water runoff instead of curbs & gutters?

•• Does the swale design include an engineered soil Does the swale design include an engineered soil matrix that will dewater rapidly?matrix that will dewater rapidly?

•• Can supplemental irrigation be provided, as Can supplemental irrigation be provided, as needed, to maintain vegetation?needed, to maintain vegetation?

•• Can native vegetation be used instead of turf?Can native vegetation be used instead of turf?

•• Who will maintain the swales?Who will maintain the swales?


Detention Detention basinsbasins

Required for flood control

Often not maintained properly

Provide minimal water quality benefits

Can breed vectorsC. Conway

C. Conway

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.


Residential roof drainageResidential roof drainageResidential roof water is Residential roof water is relatively clean, and can relatively clean, and can be easily taken out of the be easily taken out of the storm water loop.storm water loop.

Redirect down spouts Redirect down spouts to pervious areas, rain to pervious areas, rain gardens, or rain barrelsgardens, or rain barrels


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.


Commercial roof drainageCommercial roof drainage

US Bank building, McCarran & Neil Rd., RenoSparks LibraryS. Donaldson

C. Conway

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.


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.


This conceptual plan utilizes several This conceptual plan utilizes several better site design techniques, better site design techniques,

including a vegetated island that including a vegetated island that allows storm water filtration, shorter allows storm water filtration, shorter

driveways, narrow streets, and driveways, narrow streets, and alternate pavement for overflow alternate pavement for overflow

parking.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.


Other questions to ask:Other questions to ask:•• Is there a plan for phased development and Is there a plan for phased development and

clearing to minimize soil disturbance?clearing to minimize soil disturbance?

•• Are drainage flow paths as long as possible, to Are drainage flow paths as long as possible, to encourage infiltration?encourage infiltration?

•• Are impervious surfaces minimized or Are impervious surfaces minimized or disconnected with vegetated buffers?disconnected with vegetated buffers?

•• Have pervious alternatives been considered for Have pervious alternatives been considered for RV and overflow parking areas?RV and overflow parking areas?

•• Have Have bioretentionbioretention or infiltration features been or infiltration features been incorporated into the landscaping plan?incorporated into the landscaping plan?


Getting started with LIDGetting started with LID

1.1. Form a Professional Advisory GroupForm a Professional Advisory Group

2.2. Identify development categoriesIdentify development categories

3.3. Permitting and plan review proceduresPermitting and plan review procedures

4.4. Standard design criteriaStandard design criteria

5.5. Construction inspection proceduresConstruction inspection procedures

6.6. Determine responsibility for longDetermine responsibility for long--term term operation and maintenanceoperation 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 www.TMstormwater.com). 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.


Getting started with LIDGetting started with LID7.7. Develop applicable zoning and land use Develop applicable zoning and land use

regulationsregulations

8.8. Training for developers, architects, Training for developers, architects, contractors and agency staffcontractors and agency staff

9.9. Incorporate LID practices into site designsIncorporate LID practices into site designs

10.10. Develop longDevelop long--term operation and term operation and maintenance plansmaintenance plans

11.11. Inspection and enforcementInspection 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.


Any questions??Any questions??


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is an educational program for land use is an educational program for land use decision makers addressing the relationship decision makers addressing the relationship

between land use and water resource between land use and water resource protection.protection.

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strategies for coping with polluted runoff · strategies for coping with polluted runoff 5 public...

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