White Oak Neighborhood Stormwater Retrofit | Montgomery County Department of Environmental Protection

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DEP Home : Water : Restoration Projects : White Oak Neighborhood Stormwater Retrofits

White Oak Neighborhood Stormwater Retrofit

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For questions about this project, contact DEP : 311
Email: askdep@montgomerycountymd.gov

The Department of Environmental Protection is constructing twenty three new stormwater management Low Impact Development (LID) facilities including curb extensions, bioswales, tree box filters, and modified stormdrain inlets in the White Oak neighborhood along Stewart and April Lane and Lockwood Drive.

This marks one of the first multi-facility LID projects to be undertaken in the county to reduce stormwater pollution and flows on a small neighborhood scale. These small scale stormwater management facilities are designed to provide water quality treatment for smaller storm events (1.0 inch of rain), which, due to their higher frequency of occurrence, account for a significant proportion of the total pollution to our streams. Roadway LID facilities are designed to intercept water as it flows along the curb and route it through dense vegetation slowing the rate of flow and allowing the water to soak into the permeable soil mix comprised of topsoil, sand and mulch. As water passes through the vegetation and soil, pollutants are filtered out before the water flows out via an underdrain. The underdrain is connected to the existing stormdrain system.
View a larger cross sectional view of a typical LID stormwater management facility.

Curb Extensions

They are often used along roadways as traffic calming devices by narrowing the roadway width. However, slightly modified, they can also provide water quality treatment for stormwater runoff from the road surface. When it rains, water from the street flows into the curb extension through several inlets. Once in the curb extension water flow is slowed by dense vegetation and small check dams which promote absorption into the mulch and permeable soil. Most curb extensions in the White Oak project have underdrains to ensure positive drainage and prevent standing water for long periods of time. Below the underdrain is a layer of gravel which provides some water storage and allowing for infiltration into the underlying soils, recharging groundwater supplies. Excess water during larger storm events flows out of the curb extension and into the nearby stormdrain inlet. See photo.

Bioswales

They are similar to curb extensions in that they intercept water flowing off the roadway and provide filtration as water flow is slowed by vegetation and check dams within the bioswale. As with curb extensions, bioswales typically include layers of gravel (bottom), sand, permeable soil and mulch (Top). Dense vegetation in the bioswale is important to help slow water flow, promote infiltration into soil and uptake water and nutrients through the evapotransporation process. See photo.

Modified Inlets

They are standard stormdrain inlets that have been modified to capture trash, sediment and other debris washed in from the roadway. These are experimental structures that DEP is optimistic will provide a relatively inexpensive means of removing these pollutants from stormwater runoff and reducing impacts to our streams. These structures will be monitored closely to determine the rate at which debris accumulates and the frequency of cleaning required to keep them functional. If successful, modified inlets could provide some level of water quality treatment in many portions of southern Montgomery county where space and utility constraints prevent the use of typical LID practices.

LID facilities constructed at White Oak will provide environmental benefits, improve the aesthetics of the properties where reasonably possible with appropriate landscaping, and provide opportunities for community education. Maintenance of the facilities will be provided by DEP with funds from the Water Quality Protection Charge.

Design Plan

View the final design plan (PDF,27 pp, 81.4 Mb)

Project Gallery

Click the button to start the slideshow. To view descriptions of the photos, start the slideshow and enter fullscreen mode by clicking the button. Then click the "Show Info" link at the upper right corner of the screen.

Project Map

View the White Oak Neighborhood Project in a larger map

Project Schedule

Construction began in August 2011 and is expected to be completed in the Fall of 2012.

Public Meetings and Field Walks

DEP has held two public meetings to inform residents living in the area about the project and to provide an opportunity to submit comments and concerns. During these meetings the public had an opportunity to engage with Montgomery County Department of Environmental Protection staff members and learn how to contribute to water quality improvements.

Initial Public Meeting

Date: March 16, 2010
Time: 6:30-8:30 p.m.
View the Presentation (PDF,15 pp, 2.75 Mb)

Public Meeting to Review Project Design Concepts

Date: August 25, 2010
Time: 6:30-8:00 p.m.
View the Presentation (PDF,21 pp, 15.3 Mb)