Wastewater Staff Keep City Sewer Main’s Functioning
With 138 miles of sanitary sewer mains under City of Marshfield streets, Marshfield Wastewater Utility staff are responsible for keeping those mains clean and functioning.
Utilizing processes called “televising” and “jetting,” operators propel a camera through the sanitary line and record a video of each segment. Jetting is a generic name for using high pressure water to clean sanitary lines.
“There are other methods that don’t use water, but they are generally a bit more dangerous and don’t work in all applications,” explained Wastewater Superintendent Sam Warp, Jr.
Staff uses the information collected from video footage to draft a report of the condition of the line. From there, they rate each defect and prioritize them, then consider the best method to repair the line and schedule the repairs as funding allows.
“We clean and televise all lines in the city on a five year rotation,” said Warp. “Some areas see us back sooner because we know there are defects in that age of pipe, while other areas have new pipe that will last many decades yet.”
Both the jetting crew and televising crew require at least two operators. If the line is larger, or manholes are not in the street or in high traffic areas, then more operators are needed.
“Any day that the temperature is above 32 degrees outside, the jetter is out cleaning lines,” said Warp. “It operates on water, so below freezing can cause troubles with the water lines on the truck freezing up. The televising crew can achieve the best pictures above 40 degrees. With the winters lately, the guys have been out all twelve months of the year.”
In the older sections of town, Marshfield’s sanitary sewer pipes are commonly broken, misaligned, and/or leaking with water infiltrating and roots in the pipe.
“These are addressed on a regular basis, but the pipe does not get any newer unless we repair them,” said Warp. “We always grab the areas that have the most chance of causing a backup and get them repaired first.”
Warp added that the methods of repair are endless, with each situation presenting different issues.
“The best long-term solution for the main is always to dig the pipe up and replace it,” he said. “We must consider other factors like the condition of the road.”
If the road is in good shape, then digging it up is not a good choice. Staff also examine if there are other utilities in the way, how will it affect residents or businesses in the area, cost, risk factors, and potential consolidation this with other projects to get a better price.
“These all play into the decisions and that’s why we have used CIPP or Cured in Place Pipe as the main tool,” said Warp. “With this method, we actually ‘line’ the existing pipe in place. This new liner will last for decades or longer and it’s about 10% of the cost of digging and replacing with new pipe.”
Aware of the national infrastructure problem, Marshfield Wastewater is fifteen years into a plan to upgrade its sanitary sewer infrastructure.
“In about ten years from now, over 90% of the sanitary sewer mains will be either new PVC plastic or CIPP lined,” said Warp. “Both have long life expectancies and will be a great asset to the residents for generations to come.”