Maryland Department of Transportation State Highway Administration (MDOT SHA)
- Geomorphic Assessment
- Stream Restoration Concept Design Plans and Report
- Wetland Delineation
- Forest Characterization
- Forest Stand Delineation and Conservation Plan
The MDOT SHA is required to bring Maryland highways into compliance with the Maryland’s Watershed Implementation Plan for the Chesapeake Bay Total Maximum Daily Load (WIP), the NPDES MS4 Phase I and II permits, and local TMDLs by implementing stormwater and environmental BMPs.
Coastal Resources, Inc. (CRI) provided environmental services for the restoration of two tributaries to the Patapsco River north of Pinnacle Drive at West Nursery Road in Patapsco, MD as part of the TMDL Program. CRI’s work consisted of 991 linear feet of one tributary and 2,205 linear feet on the second tributary, for a total length of 3,196 linear feet. The tributaries of the Patapsco River are located within a steep valley with new development in a portion of the watershed. The streams have areas of significantly eroded vertical banks that are contributing sediment and nutrients directly into the Patapsco River which is just downstream of the restoration site.
CRI performed a detailed geomorphic assessment including a longitudinal profile and cross sections, BANCS streambank analysis, site features and mapping for approximately 3,196 linear feet of stream. The study documented existing conditions and provided the basis for the concept stream restoration design. CRI performed a preliminary hydrologic study of the project site with three study points to estimate the storm flows through the system and calibrate the design discharges and inform future hydrologic and hydraulic models.
CRI used the data collected in the geomorphic and hydrologic studies to develop for three (3) concept level (15%) design alternatives. Each design alternative consisted of a general stream plan with estimated grading limits and structures, a preliminary limit of disturbance (LOD), stream structure details, and potential access locations and paths. Each alternative balanced the restoration effort with resources impact and overall disturbance to present the SHA with three feasible alternatives. The results of the preliminary studies and descriptions of each design alternative was presented to the SHA in the Concept Design Report. The three design approaches focused on conveying design/storm flows and providing additional access to the floodplain where necessary to reduce erosive velocity and shear stresses while decreasing the overall disturbance footprint and the impact to natural resources. Chesapeake Bay TMDL crediting calculations were performed to estimate the potential sediment, nitrogen, and phosphorus reduction for each design alternative. The benefits and impacts of each alternative (including cost, resource impacts, overall disturbance, and more) was developed and discussed in the Concept Report. CRI attended design meetings with technical reviewers, as well as the property owners, to present the alternatives in the field.
CRI conducted a pre-application meeting with the regulatory agencies (USACE, MDE, DNR, USFWS) to confirm the wetland boundaries identified and discuss possible wetland and waterway impacts associated with the design alternatives.
CRI also conducted general forest characterization for the study area which extended 50 feet on either side of the stream and along proposed access paths. Specimen trees greater than 30” DBH were identified flagged and surveyed.