The Riverside County Flood Control and Water Conservation District (District) needed to install drainage improvements to reduce flooding through an area that has been developed for many decades. The District needed to select an optimal route for installation of a 90-inch diameter mainline and associated infrastructure considering environmental and engineering constraints. The District needed permits and CEQA documents to construct the improvements.
TRC conducted baseline studies and a routing alternatives analysis considering land uses, biological resources, cultural resources, paleontological resources, and permitting requirements. TRC performed Phase I and II Environmental Site Assessments to evaluate the possible presence of hazardous materials and defined requirements for soil handling during construction. TRC’s work was used by District engineers to select the final alignment design. TRC developed applications, technical studies and CEQA documents needed for project permitting and supported District staff for agency processing of applications. Permits and approvals were obtained pursuant to Clean Water Act Sections 401 and 404, Fish and Game Code Section 1602 (Streambed Alteration), and a Demonstration of Biologically Equivalent or Superior Preservation required under the regional multi-species habitat conservation plan.
TRC’s broad expertise allowed all work to be performed in-house under a single contract, minimizing our client’s contract administration and project coordination efforts. TRC’s in-house technical and regulatory experts developed practical mitigation measures where needed to avoid significant environmental impacts, allowing CEQA to be satisfied with a Mitigated Negative Declaration. This shortened the permitting time by a year or more compared to a project with a significant environmental impact requiring an EIR.