WSSC Tinkers Creek BOA
Prince George's County, MD
Tinkers Creek is a perennial stream with a 6.1 sq. mi. drainage area and 200-cfs bankfull discharge. Within the project limits there was clear evidence of the stream abandoning old channels and creating new ones that lead to the exposure of a sewer manhole responsible for sewage overflows into the stream.
AMT conducted a feasibility study to determine and prioritize the issues contributing to the lateral migration of the stream, severe bank erosion and sewer manhole and pipe exposure. The study included alternate development and prioritization for each solution. Concerns and conflicts involving the location of the exposed sewer structures, environmental impacts, wetland impacts, waters of the U.S. and tree impacts were also presented in the feasibility study. AMT explored access options, land use, physiography and soil types as additional information for the feasibility study. The project goals were established to provide long‐term utility protection from stream incision and lateral movement, minimize impacts to large trees and riparian habitat, to improve stream ecological function within the work area, ensure the solution was the most cost effective and require the least maintenance burden.
AMT provided stream restoration for 700 LF of highly eroded banks and unstable geometry utilizing a combination of bioengineering and natural channel design techniques to relocate the stream to its previous location using a series of in-stream structures installed throughout the upper reach. Point bar creation was added to help define the low-flow channel and reduce velocities in bankfull conditions. The channel was sized so the existing floodplain is activated in storms smaller than the bankfull event to provide relief from severe shear stresses without affecting the existing riparian habitat.
AMT provided full services including the initial watershed investigation, Rosgen level I-III geomorphic assessment, H&H analyses, JPA application and necessary models and reporting, Final Design plans including stream, E&S, landscaping and reforestation. AMT completed all necessary permitting, construction cost estimate and revisions to the standard specifications.