Enhancing Low Impact Development Designs Using Manufactrured BMP's

ENGINEERED SOLUTIONS

A Collection Of Case Studies That Show

How Manufactured BMP’s Contribute to Low Impact Development

2014 | www.ContechES.com/Stormwater-Blog

Enhancing LID Designs Using Manufactured BMP’s

www.ContechES.com/Stormwater-Blog



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What makes a stormwater design green? Urban stormwater planning has two fundamental purposes, minimizing the impact of increased runoff quantity and preventing pollutants from migrating to our natural waterways through stormwater conveyance systems. Natural systems comprised mainly of soil, plants and associated microbiological communities perform these functions with remarkable effectiveness in natural environments. Compared to unmitigated urban landscapes, most undeveloped areas generate lower runoff volumes, lower peak flow rates, shorter runoff durations and more moderate runoff temperatures. What runoff does occur is relatively free from urban pollutants like hydrocarbons, fertilizers, heavy metals and bacteria. Green or low impact urban stormwater systems provide these same critical stormwater quality and quantity management services, although given engineering and land availability constraints, they may take a decidedly engineered form.

The case studies presented here are real project examples where manufactured stormwater management systems were integrated into the site design to restore predevelopment hydrology and to minimize pollutant discharge. Such strategies include:

• Using underground infiltration galleries to reduce or eliminate runoff while preserving the overlying site area

for green space and vehicular loading

• Harvesting and treating stormwater from roofs and other impervious surfaces for on-site use to reduce runoff

and potable water demand

• Using flow-through treatment systems in dense environments to capture spills, gross pollutants and trash

thereby protecting downstream soil and plants

• Targeting specific urban pollutants with subsurface filtration systems using optimized filter media

• Integrating compact high-rate biofiltration systems into the streetscape to provide pollution control

Table of Contents• UrbanGreen® Solutions Staircase ..............................................................................4

» Managing stormwater close to the source

• Pitzer College – Claremont, California ......................................................................6

» California college adds stormwater infiltration systems to help promote sustainability

• Oceano Apartments – Woodland Hills, California ......................................................7

» Apartment complex meets LID goals with rainwater harvesting solution

• Salem-Keizer Public Schools – Salem, Oregon ...........................................................8

» School district uses biofiltration to provide decentralized stormwater treatment

• Ocean Parks Boulevard – Santa Monica, California .................................................10

» Complete “green street” reduces urban runoff discharges

• Huntington Library – San Marino, California ...........................................................12

» Library’s cultural landscaping meets stormwater mitigation plan

• Mathei Place – Bellingham, Washington ..................................................................14

» High-density development takes on challenge of being green

• Lake Street in Whitehall – Whitehall, Michigan .........................................................16

» Michigan’s first “green road” uses flow-through treatment to improve water quality

• Surfer’s Point – Ventura, California ..........................................................................18

» Managed retreat project provides long term solution to popular beach

• Point Breeze Office – Baltimore, Maryland ...............................................................19

» Office building follows LID principles by integrating land based and structural BMP’s


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Storing runoff, treating it and using it for irrigation, toilet

flushing, wash water, cooling make-up or other applications

turns stormwater into a valuable resource.

Biofiltration Biofiltration is a compromise between LID practices

and traditional flow through BMPs. Filtration through

a deep media bed provides a high level of treatment and

some runoff reduction. Incorporating plants and organic

material into the mix further enhances performance. Because

biofiltration is a flow-through treatment process and does not

eliminate runoff completely, it is preferred when options higher

on the staircase are not practical.

Traditional Design – Treatment Trains

Traditional stormwater criteria require

both improving the quality and

managing the quantity of runoff. One

of the best practices is to incorporate

pretreatment, detention and treatment

into an integrated system. The use of

detention and treatment systems in a

conventional design continues to provide

significant environmental benefits and

is acceptable in many jurisdictions. This

approach can meet TMDL requirements by

providing a high level of pollutant removal

and preventing erosion damage from

peak flows.

Surface InfiltrationSurface infiltration is the first option in many LID strategies. Infiltrating runoff through engineered

soils cleans the water and slowly recharges groundwater systems that supply aquifers, streams and lakes. Where viable, infiltration is an effective means of managing stormwater runoff because it often allows you to address both water quality and water quantity concerns. Practices include minimizing impervious surfaces (and using porous hardscape), rain gardens and bioswales.

Subsurface InfiltrationFor dense developments or sites with lower

infiltration rates, aboveground practices

may not be a viable solution. The next step to consider is

underground infiltration practices such as vaults, chambers

and pipes with open bottoms or perforations. Belowground

practices provide a significant storage volume and

infiltration footprint without using land that could otherwise

be developed or preserved.

Rainwater HarvestingHarvesting runoff and using it on-site

provides many benefits beyond stormwater

management. Not only does harvesting reduce runoff

from the site, it preserves municipal fresh water supplies,

eliminates the energy required to move water long

distances and eliminates CO2 emissions associated with

that energy consumption.

Solutions StaircaseLow impact development regulations

direct us to manage stormwater close to

the source and mimic predevelopment

hydrology to the maximum extent

practicable. It is easy to meet those

goals by taking a systematic approach

to selecting which BMP is right for your

site. First, select the runoff reduction

practices that are most appropriate for

your site, paying particular attention to

pretreatment needs. If the entire design

storm cannot be infiltrated on-site,

select a treatment BMP for the balance.

Finally, select a detention system to

address any outstanding downstream

erosion issues.

hydrodynamic separation

detention

filtration

retention

© 2012 Contech Engineered Solutions LLC



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In 2001, Pitzer College reimagined its campus. The college committed itself to expanding in an environmentally responsible fashion. The 2003 Housing Master Plan proposed new residence halls designed with both architectural flair and eco-friendly features. Phase I of the project, Atherton Hall, was so green it achieved LEED Gold certification.

For Phase II of the project, the construction of

Built in 2012, Oceano apartments is a 244 unit, 5.8 acre community located in Woodland Hills, California, featuring outstanding architecture and design as well as a host of the most modern and cutting edge amenities. The goal of the development was to provide residents with a unique, sustainable environment and a neighborhood feel.

Water and energy conserving technologies and practices were incorporated into the site to

Pitzer College » Claremont, CA

Owner: Pitzer CollegeEngineer: KPFFLandscape Architect: Mia Lehrer, AssociatesContractor: Bali ConstructionTechnical Description:CMP Infiltration - 163 LF of 60-in. diaALT2, perforated CMPInstallation Date: June 2011

Oceano Warner Center » Woodland Hills, CA

Owner: TDI Real Estate Holdings LLC Dune & Real Estate Partners LPEngineer: KHR AssociatesContractor: AR PipelineTechnical Description: (3) CDS® hydrodynamic separators; 88,000 gallon cistern made from 500’ of 96” diameter DuroMaxx® SRPE Installation Date: June 2012

the Mosbacher/Gartrell Center for Media Experimentation and Activism, the college set its goals even higher - LEED Platinum certification. More than 40 sustainable features were incorporated into the design of the residence halls, including a green roof, solar panels, permeable concrete, and a graywater system to collect and treat water to be used for irrigation. The project was a way to celebrate rainfall, sustainability and create a seamless transition to the Outback portion of the campus.”

Contech helped the college meet its goal by providing two stormwater infiltration systems to capture runoff, storing the water during a storm until it can be slowly released into the surrounding native soil and recharging the aquifer. Both systems use 60-in.

diameter ALT2, perforated corrugated metal pipe (CMP). The first system uses 197 LF of CMP to store 5,684 cf of runoff while the second system uses 126 LF to store 9,400 cf of runoff. The two systems were enclosed in a non-woven geotextile to prevent clogging of the perforations.

“This was beyond green design. There was no storm drain infrastructure on site; the underground detention was necessary for the project to move forward,” said Omar Maciel, Engineer at KPFF. Infiltration is a common

Low Impact Development (LID) practice. By utilizing subsurface infiltration, space is preserved for development, runoff is reduced or eliminated and groundwater recharge can occur. Contech CMP infiltration systems can be sized and shaped to meet site-specific needs, and are available fully or partially perforated. CMP detention and infiltration systems are available in all AASHTO M 36 types, with various coatings to achieve 75-100 year design service life. In 2012, Phase II of the project earned LEED Platinum certification from the US Green Building Council.

reduce the community’s overall carbon footprint. This included an UrbanGreen Rainwater Harvesting System from Contech Engineered Solutions. The 3.57 acre site was challenging because it consisted of 85% impervious surface and included 48,778 sq. ft. of landscaping. Engineers at KHR originally looked at retention as a way to control stormwater, but upon further review, rainwater harvesting was chosen as it provided the runoff reduction required by the Community of Woodland Hills in the City of Los Angeles.

A Contech CDS hydrodynamic separator was used to pretreat runoff collected from the roofs, surface parking and associated drive aisle, keeping organic material and other debris from damaging or clogging the system and to reduce maintance costs. The treated water then flowed to a 188,000 gallon cistern made from 500’ of 96” DuroMaxx Steel Reinforced Polyethylene. DuroMaxx is an ideal choice for rainwater harvesting cisterns as it is strong, lightweight, and can be made in diameters of up to 120”. Contech provided all of the pumps and controls, providing a turn-key system from a single provider. Contech also provided KHR complete sizing, engineering, and installation support.

The stormwater management design also called for two additonal CDS units to treat stormwater downstream, treating runoff from roadways not collected in the cistern. The CDS system uses continuous deflective separation to effectively screen separates and trap debris, sediment and oil from stormwater runoff.

Oceano Warner Center was honored as the Best New Construction in Los Angeles by the California Apartment Association and is LEED Silver Certified.

The 2003 Housing Master Plan proposed new residence halls

designed with both architectural flair and eco-friendly features. Infiltration

The goal of the development was to provide residents with a unique,

sustainable environment and a neighborhood feel.RWH




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Voters in the Salem-Keizer Public School District passed a $242.1 million school construction bond in 2008 — one of the largest in Oregon history. This bond included increases to school safety, renovations and upgrading of current facilities, construction of four new facilities to alleviate overcrowding, and independent oversight of all bond-related projects.

An internal high-flow bypass weir is a standard design feature of the UrbanGreen BioFilter. This eliminates the extra high-flow bypass inlet structure that would have been required with alternative biofiltration products. This configuration greatly reduced installation time while providing additional cost savings to the District. Activation of each BioFilter unit, plants and even first-year maintenance to ensure establishment of a healthy root system, are all included in the purchase price, providing additional cost savings.

Salem-Keizer Public Schools » Salem, OR

Owner: Salem-Keizer Public SchoolsEngineer: Youngman Locke EngineersContractor: Emery & SonsTechnical Description:22 UrbanGreen® BioFilters 4-ft x 6-ftInstallation Date: January 2011

The District created a construction bond campaign to share how the bond addressed these community concerns, and strengthen community relationships. Two of the new schools, Straub Middle and Kalapuya Elementary, would benefit the community through providing healthy and safe environments for educational programs, and providing access for West Salem neighborhoods, through the planned extension of Wilmington Avenue. They were working within a tight time frame to complete construction and open the new schools on schedule. As a result, a quick-installing solution that addressed stormwater management was required. The District worked with Youngman Locke Engineers to find a Low Impact Development (LID) solution.

“The LID solution was desired because it decentralizes treatment,” said Ron Hudkins, P.E., with Youngman Locke Engineers. “It also has the additional benefit of lessening the peak water runoff volume.”

The Contech UrbanGreen® BioFilter was selected for the project because it could provide a high level of treatment and partial reduction of runoff volume. The UrbanGreen BioFilter is a cost-effective solution that is a compact, versatile and reliable alternative to conventional bioretention designs.

UrbanGreen Biofilters are commonly configured with a curb inlet, but in this case the road on which the Biofilters are being used has slopes of up to 9%, so the engineers designed the units with catch basins in the street to ensure all runoff would be captured in the systems and not just flow by.

“One site challenge was the hilly nature of the site,” said Hudkins. “Wilmington Avenue traversed the entire elevation change of the site, leading to varying grades at the basin locations - from two to 9.5 percent. This called for a new design for the UrbanGreen BioFilter.”

Emery & Sons installed 22 of the 4-ft. by 6-ft. UrbanGreen BioFilters in just 6 weeks. Additionally, a Corrugated Metal Pipe (CMP) detention system composed of 336 LF of 72-in. diameter, 16 gage, Aluminized Type II CMP was used to create a system footprint of 24-ft. by 108-ft.

“We were pleased with the final outcome of the project,” said Jay Remy, Director of Communications and Community Relations for the Salem-Keizer Public School District. “We have two new schools open, serving more than 1,000 students per day in a great learning environment.”

The ribbon cutting and open house events at Kalapuya Elementary and Straub Middle schools were held in September 2011. More than 1,000 students, parents and other community members attended these and 11 other events at schools throughout the District following the extensive summer construction projects.

“The LID solution was desired because it decentralizes treatment,” said Ron Hudkins, P.E., with Youngman Locke Engineers. “It also has the additional benefit of lessening the peak water

runoff volume.”Biofiltration



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In 2008, at the request of the Santa Monica community, a project was initiated to examine the portion of Ocean Park Boulevard west of Lincoln Boulevard to Neilson Way. The community requested solutions to issues based on scale, character, health, safety, sustainability, landscaping, accessibility and circulation. After several years of planning and collaboration between community members, the City of Santa Monica and other local

“The CMP installed very smoothly,” stated Randy Slane, Construction Manager with Arcadis, the construction manager on the project. “Excel Paving Company is a great contractor and installed the large, 7’ diameter pipe and connected it with an excavator in less than an hour, like clockwork.”

Throughout the project, a few challenges were encountered, such as installation of the pipe in

Ocean Park Boulevard Green Streets Project » Santa Monica, CA

Owner: City of Santa MonicaEngineer: Kimley-Horn and Associates, Inc.Contractor: Excel Paving CompanyTechnical Description:• 4 Basins of ChamberMaxx®

• 3 Basins of Corrugated Metal PipeInstallation Date: April to June 2012

stakeholders construction for the Ocean Park Boulevard project began in December 2011 with a groundbreaking ceremony. From Neilson Way to Lincoln Boulevard, Ocean Park Boulevard will be turned into a “Complete Green Street,” resulting in a better performing, enhanced streetscape that is pedestrian and bicycle oriented, attractive and reduces urban runoff discharges into the Santa Monica Bay.

Key elements of the project included: wider sidewalks, over 100 trees, improved landscaping, a drip irrigation system, crosswalks, traffic signal improvements, parkway/stormwater biofilter swales and infiltration areas, storm improvements and more. While searching for a stormwater solution, the City and Kimley-Horn and Associates, Inc, the engineer on the project, turned to Contech Engineered Solutions for help. Both long-term clients, they knew Contech would provide a strong level of expertise in stormwater and Low Impact Development (LID) engineering.

As a solution, Kimley-Horn chose to utilize four basins of ChamberMaxx® ranging from 945 CF to 4,590 CF of storage, two basins of 84” perforated corrugated metal pipe (CMP) with approximately 4,000 and 10,000 CF of storage and one basin of 24” perforated CMP with approximately 250 CF of storage. Ideal in a shallow footprint, the open-bottom plastic ChamberMaxx allows infiltration into surrounding soil, effectively achieving runoff reduction requirements. By utilizing subsurface infiltration, space is preserved for development or green spaces above, runoff is reduced or eliminated and groundwater recharge can occur. Furthermore, ChamberMaxx’s light weight allows for installation by hand, rather than by heavy equipment, providing a green and economical solution.

tight spaces, utility conflicts and grade issues. Due to utilities buried in the area, it was imperative that the pipe size varied throughout the project in order to meet the depth requirements. In addition, the footprint was extremely restricted so the width and length of each pipe section was carefully considered. There were also concerns about corrosive soils in the area so, as a solution, the CMP was coated with polymer.

At completion, the project included improvements to over a half mile of vehicular right of way, more than 6,000 linear feet of sidewalks and the 4th Street overpass. The end result has benefited the Ocean Park neighborhood and the entire Santa Monica community by providing a working model of sustainability, multi-modality and low-impact street design.

Ocean Park Boulevard will be turned into a “Complete Green Street,”

resulting in a better performing, enhanced streetscape that is ...

attractive and reduces urban runoff discharges into the Santa Monica Bay.

Infiltration




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The Huntington Library in San Marino California is a private, nonprofit institution that encourages research and promotes education in the arts, humanities and botanical sciences. The library is replacing the current 9,000 square-foot entrance with a new Education and Visitor Center. The $60 million project features 6.5 acres of new gardens and about 43,000 square feet of educational facilities and visitor amenities.

After treatment, the runoff is directed to a below ground infiltration system made from 310 LF of pipe-arched 71” x 47” 10 GA Aluminized Type II perforated pipe designed to provided 8,731 CF of storage; 5,606 CF from the pipe and 3,125 CF from the stone. The system stores runoff in the pipe and surrounding stone during a storm until it can be slowly released into the surrounding native soil.

Huntington Library » San Marino, CA

Owner: Huntington LibraryEngineer: Breen EngineeringContractor: Kana PipelineTechnical Description: CMP Infiltration - 310 LF of pipe-arched 71”x 47” 10 GA Aluminized Type 2 perforated pipe and (2) CDS® hydrodynamic separators Installation Date: 2013

The new facility will provide much improved services for more than 550,000 visitors who come to The Huntington each year.

The new buildings are designed to be compatible with the formality, scale and materials of the original 20th-century Beaux-Arts architecture on the property. The landscaping will include gardens highlighting the natural, agricultural and cultural landscape origins of the estate in a Mediterranean plant palette.

Given the dense site and the need to comply with Los Angeles County Standard Urban Storm Water Mitigation Plan (SUSMP), Breen Engineering selected a belowground infiltration system with pretreatment from Contech Engineered Solutions to manage runoff from the site.

Water from the roof and other impervious surfaces is conveyed to two Contech CDS hydrodynamic separators. The CDS is a swirl concentrator hybrid technology that provides continuous deflective separation – a combination of swirl concentration and patented indirect screening – into a unique product. The indirect, self–cleaning screening capability of the system allows for 100% removal of floatables and neutrally buoyant material, without binding. Pretreament with a CDS removes trash and solids debris to protect infiltration beds from solids occlusion, protects outlet control structures, and isolates sediment into a single structure to provide easy maintenance.

Pipe-arch was used instead of large diameter pipe because the site was very flat with limited depth. Using pipe-arch allowed for a larger volume of storage per foot of pipe; maximizing storage and minimizing the depth of the trench.

“Breen Engineering decided to use this particular system at Huntington because it provided a concentrated treatment area for a large project acreage,” said Evan Fernandez, Civil Designer at Breen Engineering. “Infiltration being the recommended and preferred method for storm water treatment by MS4 Permittees, it gave us the option to use the CMP system. The CMP, along with the CDS units, allowed the site to maintain the original layout the architects intended, as well as utilizing the existing storm drain system in many areas to create a complex storm drain system that can

provide flood protection and treatment control.”

Installation of the stormwater management system was completed in the Fall of 2013. The new Education and Visitor Center is scheduled to open in early 2015.

The landscaping will include gardens highlighting the natural, agricultural and cultural landscape origins of the estate in

a Mediterranean plant palette.Infiltration

HDS



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In Bellingham, Washington – as in many communities in the Pacific Northwest and across the United States – the number of projects constructed utilizing green or sustainable practices is increasing rapidly. Often these projects utilize emerging technologies and construction practices and, without the economies of scale, these green features can come with a cost premium. The goal of this project is to take on the challenge

Matthei Place » Bellingham, WA

Owner: City of BellinghamEngineer: Chris Webb & AssociatesContractor: Callen ConstructionProducts Used: The Stormwater Managment StormFilter® and CatchBasin StormFilter configuration and CMP Detention (250 LF of 60-in. dia. corrugated metal pipe)Installation Date: 2008

of being green and sustainable while also meeting affordable housing requirements. The Matthei Place project’s goal is to build 14 permanently affordable single family attached homes and 21 parking places on ½ of a city block in Bellingham’s south side.

The primary challenge for this project was to achieve a level of density that is much higher than the surrounding development. The site for the project was ½ of a city block that was designated for use as affordable housing by the Bellingham City Council following the construction of a new fire station on the other ½ of the block. The original size of the site dedicated to the project was approximately 37,000 sq. ft. which included part of a vacated right of way. In order to maximize the size of the site to allow the 14 units and the required parking to be provided while maintaining some open space, additional land was needed.

When the fire station was built, about 5,000 sq. ft. of land on the project’s ½ of the block was used to provide stormwater treatment and detention/flow control in a stormwater “wet pond”. A “wet pond” provides dead storage for stormwater treatment and live storage controlled by an outlet structure for stormwater detention.

“At the level of density necessary to build this type of project, dedicating that much space to a detention pond is just not an efficient use of land,” said the project’s Civil Engineer. The engineer and the owner approached the City of Bellingham with an offer that if the project proved to provide the detention and stormwater treatment function afforded by the existing “wet pond”, the city would have to allow the land containing this pond to be added to the project.

To meet the project’s green goals and to take full advantage of the infiltration capacity of the project’s sandy loam soils, a pervious concrete pavement system was proposed for all new parking areas.

The goal of this project is to take on the challenge of being green

and sustainable while also meeting affordable housing requirements. Infiltration

The City of Bellingham agreed to surplus the land for the stormwater wet pond to the project in exchange for an agreement to manage the fire station’s stormwater for both water quality and flow control indefinitely. The addition of this land to the project site took the total project site to just about an acre – approximately 42,000 sq. ft. This additional area allowed the architect to lay out the project with more open space and allowed the construction of a bike barn to encourage non-car transportation.

To provide the required treatment for the off-site stormwater flows from the fire station, two CatchBasin StormFilters were selected. To meet the detention requirements for the off-site flows and for the roof water from the on-site homes, a 60-in. diameter corrugated metal pipe vault system was used. The new 12,000 sq. ft. on-site parking lot did not require any additional treatment or flow control as it was designed to directly infiltrate.

The off-site flows are treated by two CatchBasin StormFilters. One is a single cartridge unit located off-site in the back parking lot of the fire station. The second unit is located on-site and provides treatment for the large apron in front of the fire station and a portion of Harris Avenue. Following treatment in the CatchBasin StormFilters, the stormwater flows are directed to an on-site vault system of approximately 250 lf of 60-in. diameter corrugated metal pipe in three parallel pipes with a header. The flow from the

roofs of the 14 homes is also directed to the vault where it combines with the off-site flows and is detained prior to being released to the city’s stormwater system and ultimately into Padden Creek.

In summary, the use of the CatchBasin StormFilters and the corrugated metal vault system was part of a system that incorporated the Low Impact Development (LID) strategy of pervious pavement which allowed this project to meet its goals of affordability and sustainability. The efficient use of land in the dense urban areas is important to allow development to occur where services exist and avoid sprawl.




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For more than 20 years, challenging stormwater conditions and continued erosion have been a problem at Surfer’s Point, a popular surf break near Santa Barbara. Beach erosion, degraded water quality and flooding issues have caused tremendous damage. Coastal development, unsustainable water management practices and runoff from urban and agricultural areas further exacerbated the problem.

Surfer’s Point » Ventura, CA

Owner: Surfers PointEngineer: RRM Design GroupContractor: Tierra Contracting, Inc. /C.A. Rasmussen, Inc.Product Used: The Stormwater Management StormFilter®, 60 cartridges 8-ft. by 24-ft.Installation Date: April 2011

A collaboration of community stakeholders from government, businesses, non-profits and residents spent years debating options, and eventually chose the innovative “managed retreat” — or shoreline retreat — approach as their long-term solution to effectively manage the stormwater and stall erosion.

The design of a rainwater-permeable parking lot and sustainable stormwater filtration system were critical to the success of the Surfer’s Point managed retreat project. To provide the highest possible quality treatment of runoff water, the City of Ventura and consulting engineer RRM Design Group, chose Contech to provide a StormFilter® stormwater management system to use in combination with bioretention from a grass bioswale, “buried cobble” berm and vegetated sand dunes. This StormFilter system was designed to remove trash, sediment, oil, nutrients and heavy metals from stormwater runoff at flow rates of up to two cubic feet — that’s 900 gallons — per minute.

In addition to being the most economical solution, managed treatment is also the best environmental solution because it reestablishes a natural erosion buffer zone through redesign of the urban watersheds and environmental restoration of this 1,800-foot stretch of shoreline. To create this zone, the old rip-rap was replaced with a cobble-and-sand berm, a crumbling bike trail was relocated more than 60 feet inland, and a sustainable quality stormwater management system was designed to provide high-quality filtration near the new bike path and parking areas to treat stormwater runoff before discharge to the nearby Ventura River estuary and the Pacific Ocean.

Since two decades of problematic flooding contributed to the erosion,

the project required Low Impact Development (LID) features to capture and filter stormwater runoff for flood

control and water quality improvement.Filtration

Both the City of Ventura and RRM Design Group have years of experience working with the StormFilter product. In addition to the quality of treatment provided, StormFilter also offers quick installation. In this case, the Surfer’s Point StormFilter was installed in less than an hour from offload.

“It was critical to the success of the project that treatment of the stormwater satisfied the strict requirements of both the California Coastal Commission and the Regional Water Quality Control Board,” recalls Jerry Michael, RRM Design Group principal, who provided civil engineering services for the project. “StormFilter provided the best solution to meet all of the agencies’ concerns, and was easy to install.”

The newly renovated Surfer’s Point was engineered to appear natural, hiding the highly-sophisticated stormwater filtration and treatment system, and managing the beachfront by acting as a barrier against further shoreline erosion.

This innovative managed retreat project is the first of its kind for the state of California. It is featured on the National Oceanic and Atmospheric Administration (NOAA) website in “Shoreline Management” and is hailed as a model environmental approach to coastline restoration and stabilization.

Since two decades of problematic flooding contributed to the erosion, the project required Low Impact Development (LID) features to capture and filter stormwater runoff for flood control and water quality improvement. The StormFilter provided by Contech, working with the other biofiltration methods, met all the LID criteria.



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White Lake is a major tributary to Lake Michigan and an EPA Area of Concern (AOC). Historic industrial pollution contaminated lake bottom sediments, tainted fish and harmed water. Government officials are now working to reduce the volume of polluted stormwater that drains off the land and into White Lake.

The City of Whitehall recently completed Michigan’s first “Green Road.” The city

Lake Street in Whitehall » Whitehall, MI

Owner: City of WhitehallEngineer: Prein & NewhofContractor: Thompson BrothersTechnical Description:CDS® model 3030 hydrodynamic separatorInstallation Date: August 2012

transformed 2,800 linear feet of Lake Street from a traditional paved roadway into a state-of-the-art stormwater collection system. The system uses pervious pavers, a Contech CDS hydrodynamic separator, rain gardens and bioswales to capture and repeatedly filter stormwater runoff from 60 acres of streets and industrial land near White Lake. The Contech CDS unit plays a critical role in this unique stormwater system.

Runoff on Lake Street is diverted into a series of bioswales along both sides of the road. These direct runoff into several detention zones lined with native trees and plants. Runoff then flows into the new wetland areas. Each of these steps is designed to filter the runoff and encourage it to soak into the soil. Prior to the retrofit, runoff collected at industrial facilities east of Lake Street drained to the street without treatment. A CDS system was installed to remove trash, debris and sediment from the industrial area flows prior to treatment by BMPs within the green street. The system uses continuous deflective separation to effectively screen, separate and trap debris, sediment and oil from stormwater runoff. This greatly improves the longevity of those systems and retains pollutants where they will not come into contact with groundwater, soil or wildlife.

“The City of Whitehall is committed to being a leader in stormwater treatment,” says Jason Washler, Civil Engineer with Prein & Newhof. “With the new system, stormwater is treated multiple times prior to its eventual discharge into White Lake. The treatment methods include naturalized wetlands, bioretention, pervious pavers, and a hydrodynamic separator from Contech. White Lake is expected to be delisted as an EPA Area of Concern in 2014 as a result of the efforts of many local stakeholders, including the City of Whitehall.”

Because the road’s stormwater system is so environmentally friendly, this project will further the EPA’s goals to reduce the quantity and improve the quality of stormwater entering White Lake.

The city transformed 2,800 lf of Lake Street from a traditional

paved roadway into a state-of-the-art stormwater collection system. HDS

The runoff from an office building parking lot at the Maryland Department of Transportation on Broening Highway, Baltimore, needed to be managed. Due to the size of the site there was inadequate space for a landscape-based stormwater application that could encompass the required water quality flow rate. The entire drainage area is approximately ¼ acre making it a very tight site.

Point Breeze Office » Baltimore, MD

Owner: Maryland Department of TransportationProducts Used: The Stormwater Management StormFilter®

Installation Date: June 2012

There were various pollutants of concern in the runoff from the parking lot, including trash and debris, sediments (fine, medium and coarse), oil and heavy metals (Cu, Zn, Pb and Cd). The engineer divided the drainage area into 3 sections. The individual areas were elevated, and the runoff was conveyed by sheet flow into 3 swales using parking blocks. The swales were designed to capture and temporarily hold pretreatment and recharge volume.

The swales direct runoff into linear precast StormFilter units designed with 3 cartridges in a trench vault (10-ft. length and 3-ft. width) to treat the remaining water quality flow. Each cartridge has a capacity of 15-gpm. The cartridges are equipped with CSF® leaf media to remove sediments, oil, and metals typically found in urban runoff. When the runoff volume is greater than the volume of the system, overflow is directed to a catch basin to drain through an outfall. The system provides the same function as a sand filter, but provides the same level of treatment in a much smaller space.

The site designed was based on low impact development (LID) principles. Curbs and gutters were eliminated and surface runoff from the parking lot was treated close to the source. The StormFilter provided appropriate treatment for overflow from the swales, which eliminated standing water. This project is an example of how to integrate a structural BMP with a landscape-based BMP to achieve the desired stormwater management goal and follow low impact development principals. Stormwater runoff is managed close to its source using a multi-benefit natural feature system, in this case vegetated swales.

The StormFilter is used to provide polished effluent quality within a tight footprint, so the water quality flow from the design storm was adequately treated. Meanwhile the integrated system was able to convey the peak flow, avoiding the potential problems (water ponding, scouring) that can be associated with swales.

Based on low impact development (LID) principles, curbs and gutters were eliminated and surface runoff from the

parking lot was treated close to the source.Filtration

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Quick Links• Stormwater Solutions – www.conteches.com/stormwater• Rainwater Harvesting Brochure – www.ContechES.com/rwh• LID Application Guide – www.ContechES.com/lid• Professional Development Articles – www.ContechES.com/pdh

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Enhancing Low Impact Development Designs Using Manufactrured BMP's

Engineering

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