KCI prepared a water quality management plan (WQMP) for ten Baltimore Harbor terminals owned and operated by the Maryland Port Administration (MPA). The goal was to help the agency meet National Pollutant Discharge Elimination System (NPDES) Municipal Separate Stormwater System (MS4) permit requirements and the need for pollutant load reductions from the Chesapeake Bay nutrient and sediment Total Maximum Daily Load (TMDL). The plan was developed to provide a description of existing conditions, potential pollutant sources, existing stormwater controls, recommendations for improvements, and an implementation plan. To support MPA’s reporting requirements, the plan provides:
- Inventory of existing stormwater controls, delineation of drainage areas, and calculations of impervious treated and untreated area
- Modeling of existing nutrient and sediment loads and reductions using methods compatible with the Chesapeake Bay TMDL
- Analysis of potential of stormwater retrofits and non-structural measures and recommendations for those that are appropriate for MPA facilities
- Concepts and cost estimates for specific stormwater retrofits and estimates of pollutant load reductions from recommended treatment measures
Our team developed GIS-based data systems to map existing storm drain systems, stormwater management best management practices (BMP), drainage areas, and land cover and impervious areas. KCI field crews assessed 24 potential hotspot sites to evaluate potential pollution sources, including vehicle operations, outdoor materials storage, waste management, and buildings. Recommendations included follow-up inspections, retrofits, and pollution prevention education.
The team’s approach to retrofitting stormwater treatment was designed to identify and implement a set of projects that would be acceptable to the Chesapeake Bay Program and Maryland Department of the Environment, would provide as much pollutant removal as possible, and would not require significant change in port operations. TMDL compliance was the driver behind the site search, with regulatory acceptability and potential pollutant removal as the main selection criteria. Site evaluation included existing BMPs to identify treatment systems for retrofit to provide better pollutant removal, locations where new stormwater treatment could be constructed, and potential for area-wide controls.
Following development of the plan, KCI installed a floating treatment wetland at the mouth of Cox Creek as a pilot project for the area-wide treatment approach.
Bill Frost, PE, D.WREWatershed Planner
Plans were developed for Cox Creek, Duke, Dundalk, Fairfield, Hawkins Point, the Intermodal Container Transfer Facility, Masonville, North and South Locust Point, and Seagirt Marine Terminals. Each plan included calculations of land cover and impervious area; descriptions of the drainage network, outfalls, offsite drainage entering the terminal, and a description of existing BMPs, as well as pollutant load model results for total nitrogen, total phosphorous and total suspended solids.
The assessment of potential retrofit sites conducted for each terminal resulted in seven recommended projects.