Delaware County Community College Stormwater Management Techniques

Description

Delaware County Community College (DCCC)’s comprehensive plan to improve water quality and environmental stability within the Crum Creek watershed aims at upgrading aging stormwater management techniques in conjunction with the construction of a new Science Technology Engineering Math (STEM) complex. The new 132,000 square foot STEM complex at DCCC clarified the need for bigger-scale stormwater Best Management Practices (BMPs) and that components of some 2005 improvements using Pennsylvania Department of Environmental Protection (PA DEP) 2003 grants were deficient.

Components of the first phase of the project known as the Martin’s Run Headwaters project was completed in 2005 with Growing Greener grant funds and included: 1) Raising the level of the wet pond and installation of a check dam; 2) Pervious pavement with infiltration bed(now demolished) and 3) Erosion control measures (now demolished). The STEM complex to be completed by 2009 incorporates: 4) additional infiltration beds and 5) green roof.

For a plant list associated with the STEM complex improvements, please click here. For a corresponding layout of the planting scheme (also includes plant list), click here. For a partial land development plan for the STEM complex including outlines of infiltration beds and drainage, click here, and for plan outlying additional sitework at STEM, click here.

1) Raising the level of the wet pond and installation of a check dam
In order to increase the effectiveness of aging stormwater management techniques on campus, the College upgraded a wet pond and sediment pond in 2005. The wet pond was not holding enough water during storm events, while the sediment pond was overloaded with sediment. A concrete and steel dam called a “weir” was constructed to raise water levels about one foot in depth and store additional volume within the wet pond to mitigate area flooding. More water is now treated before flowing into Martin’s Run, decreasing downstream pollution and erosion. Raising the level of water within the wet pond reduces the sediment load borne by the downstream sediment pond, where the springhouse is found. This addition was a clear alternative to dredging. The thick vegetative overgrowth in the pond benefits the environment by absorbing pollutants. Invasive Phragmite, known as the Common Reed, retreated and no longer occupies the center of the wet pond.

2) Porous pavement with infiltration bed (now demolished)
In 2005, a 3,164 square foot porous parking lot and 3,076 square foot subsurface infiltration bed were constructed at Delaware County Community College in front of Employee Parking Lot #2. Best stormwater management techniques were compatible with the features of the landscape, making it possible to capture runoff from the sloping landscape. The stone subsurface infiltration bed was constructed beneath the porous pavement. According to estimates calculated by Cahill Associates, the infiltration bed intercepted water from about 1.7 acres of paved parking area, but the surface area could have been greater due to the tiered nature of the lots. The drainage area for these BMPs was 26,229 square feet. The College purchased a pavement vacuum device to clean the pervious pavement more frequently than recommended. Since 2005 the porous pavement and underlying infiltration bed have been replaced by newly constructed infiltration beds, described in bullet #4.

3) Erosion control measures (now demolished)
An erosion control blanket was installed to prevent erosion within the grass islands and in adjacent wooded areas. Three-foot wide earthen berms were built between stormwater beds to barricade water from flowing into the grass islands and woods, carrying it instead towards inlets into the infiltration system. The installation of earthen berms was less costly and disruptive than a comparable solution entailing the creation of taller curbs. On the other hand, the downside of earthen berms is that they are vulnerable to erosion. These erosion control measures were replaced by larger infiltration beds.

4) Additional infiltration beds 
Infiltration beds have been added throughout the campus in conjunction with the new STEM complex. Two have been added underneath a new parking lot, and measure 54 feet x 100 feet x 39 inches, and 54 feet x 35 feet x 36 inches. There is also some newly created open space on campus, where the pervious pavement and infiltration trench once stood. Underlying this new green area is an enlarged infiltration bed. All of these infiltration beds work similarly: runoff during storm events is captured through inlets, through which stormwater is carried to the infiltration bed to be stored and infiltrated to reduce surface pollution and recharge groundwater aquifers. All these beds come equipped with an overflow piping system that allows for excessive water to drain off elsewhere. These infiltration beds are space efficient since ground level facilities such as trenches or basins would need additional room on the site.

An expansion of an existing 1995 basin is also expected to be completed as well as yet another infiltration bed, which should be installed beneath an existing parking lot. These upgrades should be completed before the 2009 STEM project deadline.

5) Green roof
The STEM complex’s green roof will be installed on the science building and will include wild grasses planted on 2-3 feet of dirt. Architects are currently working on the green roof design

Location

County: Delaware
Watershed: Crum Creek

Delaware County Community College is found at 901 South Media Line Road in Media, Pennsylvania. A sub-watershed of Crum Creek known as Martin’s Run passes through campus property. A 400-foot concrete swale directs stormwater runoff from Route 252 onto campus, and then into a wet pond via a grass swale at the upper end of campus. The sediment pond, where a small springhouse is located, drains downstream into a large wet pond, which feeds into Martin’s Run.

Partners

Delaware County Community College
Cahill Associates (consultants) (2005 project)
Lechmanik Inc. (contractors) (2005 project)
Pennsylvania Department of Environmental Protection (2005 project)
Burt, Hill (architects, landscape architects) (2009 project)

Cost

2005 project
The porous pavement parking lot and infiltration bed cost an estimated $31,722, or about $1,670 per parking space.
Weir (concrete/ steel dam) cost from $500 to $1,000 and was installed by DCCC facilities staff.
Pennsylvania Department of Environmental Protection Growing Greener Grant (2003): $50,000.

2009 project
Currently unavailable.

Contact

Contact for 2005 project
Daniel Wible, P.E. (project engineer)
Water Resources Engineer
Cahill Associates, Inc.
610-696-4150
dwible@thcahill.com

Contact for 2009 STEM compound project
Tony DeLuca
Director of Facilities
Delaware County Community College
901 South Media Line Road
Media, PA 19063-1094
610-359-5110
TDELUCA@dccc.edu

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