Brudis & Associates, Inc. (BAI) was responsible for Base Overall Design and Phase I Design to upgrade the Waldorf Urban Redevelopment Corridor (WURC) section of Old Washington Road to meet the county’s redevelopment effort of the 300-acre WURC zones and the restoration goals of the county’s Municipal Separate Storm Water System (MS4) National Pollutant Discharge Elimination System (NPDES) permit. BAI prepared a Storm Water Management (SWM) master plan for approximately a two-mile stretch along Old Washington Road, and developed a base concept design to determine the feasibility of designing Old Washington Road as Green Street and maximizing the storm water management for the full drainage watershed. Based on the concept design, BAI developed detailed design plans and acquired the required permits for Phase 1, which encompassed approximately 2,600 linear feet along Old Washington Road, from MD 5 Business to Railroad Place. BAI utilized the vision plan developed by the county and provided design guidelines to select potential BMP sites for private and public development zones across the corridor. The goal was to provide the County a framework for storm water management and drainage improvement within the corridor for future development, as well as the county’s roadway improvement project along Old Washington Road.
Storm Water Management Master Plan.
With detailed field study and desktop analysis, BAI prepared a Storm Water Management Master Plan by implementing a combination of Environmental Site Design (ESD) and SWM Ponds practices to meet both water quality and quantity treatment requirements for the development corridor. The master plan was divided into sections for private and public development to meet the water quality requirements separately. The quantity requirements were met for each Point of Investigation (POI) through use of existing/proposed regional storm water management ponds in the related drainage basin. A number of existing storm water management ponds were retrofitted to achieve additional quality and quantity treatment goals. The project was considered to be a new development and a full treatment of 2.5 inches was implemented to achieve reduction rates of 52% Total Phosphorous, 72% Total Nitrogen, and 83% Sediments. BAI also optimized the master plan by adopting minimum possible changes to the existing condition of development corridor. After the Storm Water Management Master Plan was completed, the detail design of phase 1 development was developed. BAI has submitted a SWM Master Plan Report, Drainage Area maps and CAD Drawings for the project. Total cost of the master plan was estimated to be $13,791,870 and the cost per acre impervious area treated was $53,056. An overall Impervious Acres credit of 316.39 Ac was also estimated from the master plan.
Challenges faced during the project design stage included:
- Consideration of new development for SWM design required a stringent 100% impervious area treatment
- Relatively flat terrain challenged drainage improvements and SWM required significant elevation drops
- Shallow ground water table in many locations restricted BMPs using filter media
- Water quantity control for corridor (considering all current and future public & private development) using regional SWM ponds since typically public and private development water quantity control are separate