The Manhole Replacement project is designed to ensure a reliable sewage system flow. The district uses manholes to access the sewage lines for maintenance and repairs. The failure or collapse of a single manhole can cause blockage and backup in the sewage system.
The district will issue a bid in 2019 to replace 20-25 important manholes along the main trunk line and should be completed within six months of the start date.
Older manholes were made of concrete and their inner linings were coated with a protectant to resist corrosive hydrogen sulfide (H2S) gas, which is released by passing sewage. The old manholes along the main trunk line were rated to last 10-15 years.
By contrast, the new manholes will still be constructed of concrete, but they will be lined with fiberglass, which are rated for 20 years.
“We have accessed other fiberglass-lined manholes that have been in the system for 20 years, and they still look new,” said Charlie McGinnis, the district’s general manager. “These manholes are a sound investment for the water district’s customers.”
The current network has between 2,000-3,000 manholes throughout the district. Depending on the size of adjacent pipes, manholes are located every 500 or 1,000 feet, in accordance with state requirements.
The district expects to issue a bid for the manhole replacement project in 2019.