GOVALLE WASTEWATER TUNNEL MANNED INSPECTION

OVERVIEW The City of Austin, Texas placed the Govalle Wastewater Tunnel into service in 1988. The Govalle Tunnel conveys wastewater generated in central Austin, Texas and the downtown area to the South Austin Regional Wastewater Treatment Plant (SAR WWTP). The Govalle Tunnel is an approximately 8 mile long, 96-inch internal diameter, cast-in-place concrete tunnel installed at an average depth of 100 feet. A map of the tunnel is shown on Figure No. 1. Figure No. 2 illustrates a cross section of the tunnel construction. There is no direct access to the tunnel. There are five sites with connecting laterals ranging from depths of 63 to 129 feet and lengths of 42 to 285 LF that convey wastewater flows into the tunnel. Each lateral includes a Parshall flume, which measures the wastewater flows before entering the tunnel, as well as a drop shaft, which the wastewater enters after the flume and drops into the tunnel lateral. An access shaft is located immediately downstream of the drop shaft. Figure No. 3 shows the general arrangement for each lateral. The distance between laterals are also shown on Figure 1 and range from 3,829 feet to over 17,050 feet.