Case Study: Water Resource Investigation — Tunneling Impacts

Client: San Manuel Band of Serrano Mission Indians Location: San Bernardino County, CA Contact for water resource projects: Tim Flynn

Project Background & Challenges

The Tribe relies on a bedrock aquifer to supply its spring water bottling plant. A major conveyance tunnel is currently under construction on USDA Forest Service land in the vicinity of this plant, prompting concerns about potential effects on this water supply. Aspect was engaged to investigate these impact and support the negotiation of mitigating measures.

Solution

To evaluate the impacts of tunnel construction on the bedrock aquifer, Aspect designed and installed an automated, high-resolution system for monitoring pressure and flow. This work also entailed assessing tunnel-lining methods, tunnel inflows, and drawdown in monitoring wells; we also modeled the fractured-rock aquifer system and installed surface water gauges. During regular meetings with the tunnel owner and Forest Service staff, we work cooperatively to develop tunnel design and construction improvements that will minimize groundwater impacts. Our technical support has helped the Tribe negotiate with the tunnel owner and various federal agencies.