The Railroad Commission of Texas, Abandoned Mine Land Program (AMLP) received notification from a private landowner regarding subsidence and erosion features associated with historical underground coal mining on their property. AMLP promptly investigated the landowner’s concerns and confirmed the site’s eligibility for AMLP reclamation. AMLP has an existing professional engineering services contract with Trihydro that allowed them to quickly issue a work order for design support.
The project’s scope involved designing a drainage channel to mitigate impacts from a subsidence feature on a private property, which was causing erosion on the landowner’s property and flooding on a neighboring property. Subsidence features may form when soil and rock collapse into mining voids, creating depressions or openings into the historical mine workings. Subsidence features can cause a range of concerns, including property damage, safety hazards, and environmental impacts like erosion and flooding. Project tasks included geotechnical drilling and soil sampling, topographic surveys, engineering design, wetland delineation, and United States Army Corps of Engineers permitting assistance.
Trihydro worked closely with AMLP to develop a channel configuration that would mitigate the subsidence feature, control erosive stormwater velocities, and minimize potential flooding of the neighboring property. The design involved an auto-longitudinal profile that leveraged geomorphic design, which mimics natural processes. Trihydro designed a channel with a sinuous shape that meanders like a natural stream and uses the shape of the channel, instead of riprap, to reduce flow velocities below erosive levels. Using the geomorphic channel design came with the added benefits of reduced costs from less riprap, an enhanced aesthetic value from mimicking a natural stream profile, and a more resilient landscape from incorporating natural processes.
Stakeholders included the AMLP, private landowners, and the United States Army Corps of Engineers. Trihydro served as the prime consultant responsible for design and topographic surveying, and its core team included Balcones Geotechnical, LLC for the geotechnical work, GCO Labs for soil analysis, and SWCA for wetland delineation.
Trihydro completed design work in six months, allowing construction with funding from the Infrastructure Investment and Jobs Act (IIJA) to begin. The project was the first AML IIJA-funded project completed in the nation.