The Powder Mill Run (PMR) Restoration Project was the proposed site to mitigate stream, wetlands, and water quality impacts associated with MDOT MTA’s Baltimore Red Line Project. The Baltimore Red Line Project included 14.1-mile, east-west railway connecting the areas of Woodlawn, Edmondson Village, West Baltimore, downtown Baltimore, Inner Harbor East, Fells Point, Canton, and the Johns Hopkins Bayview Medical Center Campus. MDOT MTA put the Red Line Project on hold and the PMR Restoration Project was not advertised or constructed. The Powder Mill Run (PMR) Restoration Project was originally initiated by the City of Baltimore’s Department of Public Works (DPW) to stabilize and restore the current conditions of Powder Mill Run beginning at the outfall of the Northern Parkway culvert west of the Wabash Avenue intersection and extending approximately 3,800 feet downstream to the Northern Parkway culvert at the Liberty Road intersection. Baltimore City had prepared 60% Design Documents. Coastal Resources, Inc. (CRI) conducted an extensive site search within the affected Baltimore Red Line Project watershed for suitable mitigation opportunities. PMR was selected as an effective location to mitigate for the corridor impacts to waters of the US, wetlands and water quality stormwater management (SWM). The proposed 3,800 linear feet of stream restoration exceeded the project stream mitigation and water quality SWM needs. In a letter of understanding, MTA and Baltimore City agreed that any stormwater quality credits achieved through PMR restoration in excess of those required by the Baltimore Red Line would be available to the City for application towards any regulatory permit or requirement the City may need to satisfy. In order to mitigate for unavoidable permanent wetland impacts related to the construction of the Baltimore Red Line Project, 3.27 acres of wetland mitigation was also proposed at the PMR Restoration Project. CRI obtained and reviewed all pertinent readily available existing data of the study area, including Baltimore City background documents and GIS data, soil surveys, USGS quadrangle mapping, aerial photography and other relevant information gathered by previous Baltimore City studies such as soil borings, well-monitoring data, and wetland delineation data. CRI inventoried the entire site to evaluate potential wetland restoration/creation areas, potential hydrology sources and reference wetland areas. In addition to determining restoration/creation opportunities and the scale of proposed activities, existing habitat types and features were inventoried. The evaluation focused on quantifying characteristics of each existing habitat feature. The site assessment and inventory also evaluated existing vegetation on-site and in adjacent upland and wetland forested areas to gather information on suitable and potential plant species and communities that could be achieved on the site. CRI set-up, monitored, and evaluated data from up to ten (10) groundwater monitoring wells/piezometers on the site including wells located within adjacent reference wetlands. This information supplemented the previously collected data in areas where adequate data were not collected. The wells were monitored and maintained for one year and through the completion of 100% design. Monitoring wells were evaluated frequently to ensure proper function, to download data, and to confirm water surface elevations collected at each well. CRI collected soil samples for proctor test, as necessary, during drilling of groundwater wells. These samples were sent to a lab for proctor test in order to estimate lateral and vertical infiltration rates. CRI also used groundwater data to estimate infiltration rates. Soils were classified according to USDA standards during well drilling. Infiltration rates provided data for water budget modeling. CRI located and documented any seeps located on the proposed mitigation site. CRI performed survey work to tie the well and existing wetland or seep elevations to a commonly known datum. CRI developed a water budget that incorporated water inputs (including precipitation, runoff, and potential groundwater sources) and water outputs (including evapotranspiration, infiltration, and outflow). Additional analysis was performed to compare and validate available localized/regional precipitation data with collected groundwater and soil information for further development of the water budget models. Frequency of flooding from adjacent waterways was used as an input for the water budget. CRI used the watershed and sub-watersheds and calculated times of concentration for use in hydrology estimates provided by the stream designer. Appropriate regional curve data for bankfull discharges was reviewed. In addition, the results of the 2D modeling being developed for the stream design was reviewed and incorporated into the analysis of surface hydrology. A wetland creation design was developed using data collected in previous tasks, along with continued and frequent coordination with the stream restoration designer. The wetland design and stream restoration included an integrated design since wetland hydrology was largely dependent on the proposed stream grading. Geology and soil data were analyzed for permeability and hydraulic conductivity to determine water infiltration rates. CRI investigated whether any of the existing species are invasive and could pose a serious threat to native wetland vegetation establishment in the created wetland. CRI developed the semi-final design (65%) and final design (85%) report, plans, specifications, and estimate. CRI also presented the design strategy to stakeholders and review agencies at milestone meetings. In addition, contract documents (100%), including plans, specifications, and estimates required for project advertisement were prepared. Coordination with Baltimore City regarding access, safety, design features, and vegetation and wildlife management was conducted extensively throughout the project. CRI prepared the Federal/State Joint permit application and plates for impacts to obtain the wetland and waterway construction authorization associated with the project. Location: Baltimore City, MD Client: MDOT Maryland Transit Administration (MTA) Key Services: Hydrology and HydraulicsGroundwater MonitoringWetland Mitigation DesignAgency CoordinationPermitting