1.5 Years of Heavy Construction in 1.5 Hours — Practical Engineering

Quick Overview

The new sewage lift station outside San Antonio, Texas, was constructed over 1.5 years to expand wastewater capacity and provide redundancy for a rapidly growing area, involving deep excavation, precast wet well installation, complex piping, and robust electrical infrastructure.

Key Points: The project constructed a new sewage lift station outside San Antonio, Texas, to increase wastewater capacity and provide redundancy for a rapidly developing area. Construction began with excavating a 30-foot deep hole, requiring sloped sides for the first 10 feet and a slide rail shoring system for the remaining depth due to the narrow site. The primary component, a precast concrete wet well, was assembled from 15-ton segments, sealed with gaskets and grout, and then leak-tested by filling it with water for several days. Backfilling around the wet well and in pipe trenches utilized Controlled Low Strength Material (flowable fill), a self-compacting cement slurry, which allows for easier future excavation for pipes. Three sewer lines were connected to the wet well, with holes core-drilled on-site for precise alignment, and flexible couplings installed to accommodate movement. Doghouse manholes were installed over existing active sewer lines, and large plug valves were integrated into the system, requiring bypass pumping to divert wastewater during installation. The site was graded with compacted select fill and native clay, and concrete slabs were poured for the electrical shelter and equipment, with rigorous quality control tests performed on the concrete.

Context: Located outside San Antonio, Texas, a rapidly developing region, the construction of a new sewage lift station became essential to meet the increasing demand for utilities from new homes and businesses. This project, a collaboration with the San Antonio River Authority, aimed to expand the existing sewage system's capacity and introduce redundancy, ensuring continuous wastewater management even during maintenance periods. Lift stations are critical where gravity-fed sewers cannot reach treatment plants, requiring wastewater to be pumped to higher elevations.