Environmental Site Design
Nobis Engineering, Inc. provided stormwater management and sediment and erosion control design services for the replacement of the Health Clinic at the Naval Academy. The 101,589-square-foot clinic will service the US Naval Academy and Naval Station in Annapolis and Tenant Commands at the former enlisted men’s club location. Supporting facilities include utilities and parking. Nobis designed the entire site to meet 100% of the State of Maryland's (MDE) Environmental Site Design (ESD) requirements through the use of:
- Eight bioretention areas: The bioretention facilities provide water quality by passing runoff through a filter bed comprised of sand, soil, and organic matter. They are equipped with underdrains and a riser structure for overflow. The ESD volume is provided within the media, accounting for 40% voids, and 12 inches of ponding on the surface. The bioretention areas for this project were designed as either micro-bioretention, if the drainage area could be kept to one half acre or less, or standard bioretention if the drainage area was greater than one-half acre. The micro-bioretention areas are equipped with a 20-foot grass pre-treatment area prior to inflow into the facility. The standard bioretention facilities are equipped with a pre-treatment sedimentation basin that is designed to accommodate 10% of the water quality volume. These provisions were made to comply with MDE requirements.
- Bioswale: The bioswales provide water quality treatment by vegetative filtering through the same media as bio-retention areas and sedimentation. The 12 inches of ponding can be credited toward meeting the ESD volume requirement due to the use of concrete check dams. Additional water quality volume is provided in the filter media similar to bioretention areas.
- Infiltration trench: The infiltration trenches promote recharge to ground water to provide water quality treatment. The trench is filled with washed stone.
- Pervious pavers: Pervious pavers are proposed in the service yard area and will provide water quality treatment at the source by promoting infiltration to groundwater.
The ESD facilities were designed per MDE requirements and permitted with an expedited process through MDE. A watershed analysis was performed to determine the adequacy of the downstream channel receiving runoff from the clinic.
The rendering is courtesy of RLF, the lead designer on the project.