Sewer Main manhole collapse

From Wednesday evening:

A 15-inch sewer main Manhole collapse was reported by ABS Freight at 401 E. 14th St. at about 5:15 p.m. Wednesday. The manhole is more than 40 years old and collapsed due to age and hydrogen sulfide corrosion. The sewer main flows into the Canyon Lakes Sewer Trunk Line that flows to the SEWRP.

Approximately 1,000 gallons per minute was flowing to the surface and into a culvert that feeds into the Canyon Lake System south (downstream) of MacKenzie Park. Because of the volume of flow, we estimate that we will have lost more than the 100,000 gallon threshold that requires us to notify the media.

Our plan of action is to dam off the flow of sewage and pump it back into the functioning sewer line downstream of the collapsed manhole. This will stop the flow to the Canyon Lakes. Our crews will be working this evening to create the dam and to begin the process of routing the sewer line around the collapsed manhole so the sewage can continue to flow as normal.

We will be watching the Canyon Lakes for fish kills and reporting our corrective action to the TCEQ as required. We are also checking the rest of this sewer main for potential problems. Some of this segment of sewer main may be part of the recommendations in our recently completed Sewer Master Plan for replacement of aging infrastructure.


From Wednesday night:

Approximately 2 hours after we received notice (7:30 p.m.) of the sewer manhole collapse, the sewer discharge subsided significantly and we did not need to create a dam to contain and re-route the discharge of sewage.

During the night time is typically the lowest flow of sewage and the best time to make repairs. Our crews will be working until approximately 3:00 a.m. Thursday morning to clean out the rubble from the collapsed manhole, open the sewer line up and install a new sewer manhole.