Mount Olivet Cemetery -

LID

Mount Olivet Cemetery in Washington, D.C. sits on a historic hill overlooking the monuments of the nation’s capital.  The largest Catholic Cemetery in D.C., it consists of approximately 80 acres of total area, with 10 acres of impervious surface, mostly roads. Tetra Tech, The Nature Conservancy, and the associated entity District Storm water LLC have implemented a multi-phase approach to generate storm water retention credits (SRC) for Mount Olivet Cemetery.

 

This is a collaborative design-build project between EQR and Tetra Tech.  EQR is the prime contractor on this project and has subcontracted out the design work to Tetra Tech.  The original concept of the project was created by the Anacostia Watershed Society (AWS) and from that concept design, our current project was formed.  The cemetery is subject to substantial storm water fees under the 2013 Storm water Regulations of the District of Columbia mainly due to a large amount of impervious cover on the cemetery site.  The age of the cemetery also played a part in how they were impacted by those regulatory fees. It’s old and much of the existing infrastructure is unable to adequately handle the storm water volume on site.

 

Our goal is to install five areas of bioretention facilities that can provide 133,500 gallons of storm water retention volume.  Due to the soil conditions at the cemetery, the ground infiltration rate was extremely poor (good brick clay means mostly impermeable).  Therefore, we are capturing storm water via sheet flow based on the topographic data of the cemetery and retaining and treating that storm water by way of conveyance rather than infiltration. The water is not designed to infiltrate into the ground, but instead is piped through the BMP via an underdrain after being treated through soil media and washed gravel and discharged at defined points to drain into existing storm water infrastructure. 

 

Due to the absence of infiltration, the volume of this BMP is all about ponding.  Therefore, it is critical we install the block retaining wall and concrete curb to design parameters, as well as the extent of excavation.  The primary function of the bioretention facilities is to slow the velocity, treat and convey storm water.  To perform that function, the storm water must first find its way into the facility. Storm water enters the facility via sheet flow from grass areas and impervious asphalt cover.  Once captured within a facility, the storm water is treated and conveyed to the desired discharge location.  Understanding how the bioretention facility treats and conveys storm water requires a review of the facility components that allow it to effectively manage storm water.

 

The cemetery has frequent visitors due to its age and historic value.  This historic site will soon become a more environmentally friendly site for D.C. creating cleaner water for the

surrounding communities.

 

Learn more about Mt. Olivet

 

 

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