Site work for a civil project in San Diego, California. Completed plans call for site work for a bridge / tunnel; and water / sewer project.

The Water Authority's First Aqueduct consists of two 48-inch diameter pipelines that convey both treated and untreated water by gravity. When Pipeline 1 was installed in 1947, multiple tunnels were constructed to maintain the hydraulic grade through the hills in San Diego County. When Pipeline 2 was constructed in 1954, the two pipelines were connected at the tunnels, effectively creating a single pipeline from an operational standpoint. The First Aqueduct conveyed chlorinated Colorado River water until 1992 when the northern section was converted to treated water. The treated water section includes three tunnels owned and maintained by the Water Authority: the Lilac, Red Mountain, and Oat Hills tunnels. A December 2019 tunnel inspection identified multiple defects and groundwater infiltration in all three tunnels. The Water Authority completed infiltration repairs in all three tunnels at that time. The tunnels were inspected again in December 2020 and similar conditions were found as in December 2019, with infiltration repairs required in the Red Mountain and Oat Hills tunnels. During this inspection, the Water Authority also performed three-dimensional scanning of the tunnels to obtain baseline geometry data for future inspections and tunnel rehabilitations. Estimated Value $12,000,000 - $17,000,000 *The value for this project is based on a financial range. The value is listed as the highest possible cost from the range provided by a stakeholder or official project document.