Problems with clay pipe being installed as part of the $9 million Woodward Avenue project are being addressed.
Public Works Director Mark Houghton noted the contractor has been working on a solution to provide adequate support for the clay pipe. Residents have reported instances of pipe cracking and developing leaks. They have seen thin sleeves of PVC piping being placed inside the affected pipe.
The area has a high water table plus the sandy loam soil can pose issues. Houghton noted soil engineering was done as part of the design.
“This is no walk in the park,” Houghton said of the project.
Houghton said the contractor is faced with putting support in place while dealing with relatively narrow trenches “that don’t leave a lot of working room.”
The 15-month timetable takes into account the complexities of segments of the 2.5-mile long project that stretches from South Main Street to a point west of Airport Way. It entails putting in place major storm and wastewater lines to accommodate future growth for at least the next 20 years south of the 120 Bypass. The last phase includes putting in a new two-lane road with a tree-lined median and other improvements.
The phasing where only one segment will be torn up at a time is a direct result of the city’s experience with a project on Woodward Avenue east of Van Ryn Avenue to Atherton Drive that was torn up for over a year due to issues with making sure pipe was properly supported.
The city also experienced problems of a similar nature when new pipe was placed 10 years ago on Button Avenue.
Some members of the development community openly questioned the city’s decision to go with an all gravity system. They argued against the high upfront cost of a gravity system compared to what a combined forced pump and gravity flow system would entail. The city countered that a gravity system would have lower long-range operating costs.
Clay pipe was chosen due to the fact it is significantly less susceptible to chemical breakdowns compared to other materials.
Another criticism of the all gravity system by some developers was the fact the pipe had to go deeper to make it work than a design that encompassed pump stations. The concern was that it would be more likely to have water seepage from groundwater which in turn would reduce capacity at the wastewater treatment plant. City staff disputed that contention.
City officials have pointed out high water tables are a way of life in many parts of Manteca. The Daniels Street extension that opened up the Stadium Retail Center, as an example, also dealt with a high water table.
Residents contacted by the Bulletin praised Floyd Johnston Construction for keeping inconvenience to those living along Woodward Avenue at a minimum.