Wastewater issues have become a high priority. A number of cities have found that sewage systems not properly maintained can prevent or curtail new business and residential developments — not to mention the public health problems that can occur. A number of major cities have already faced costly enforcement actions by state and federal environmental agencies.
As a driving force behind the sanitary sewer rehabilitation movement in Houston and a pioneer in trenchless methods, Henry N. Gregory Jr. was chosen by the Gulf Coast Trenchless Association as this year’s recipient of the prestigious Most Valuable Professional Award, presented during the Underground Construction Technology International Conference and Exhibition held in Houston.
Recognized as a leader in identifying and addressing infiltration/inflow problems, sanitary sewer overflows (SSOs) and collection system operation and maintenance, Gregory has worked in increasing areas of responsibility throughout his 28-year career for the city of Houston. He brings a wealth of knowledge and experience to his current role as deputy assistant director for the Utility Maintenance Division, Department of Public Works and Engineering for the city of Houston.
Houston was already taking a leadership role by aggressively using its resources to evaluate its systems when the Texas Natural Resource Conservation Commission (TNRCC) issued a two-part order to the city in 1987. The 10-year program contained 175 elements the city would have to meet to remain in compliance. One of those elements included eliminating all wet weather overflows and control of infiltration in flow. Over the next three years the city would conduct an $8.5-million intensive flow monitoring program as a result of this mandate.
“To help us determine where the city was getting extremely high rates of inflow, we ended up having to evaluate approximately 80 percent of the city’s 1,373-meter basins,” explained Gregory. “The 80/20 rule didn’t apply here. Our pipes were in worse shape than we had first anticipated. What we found was that we had 80 percent of the problems in 80 percent of the systems.”
According to Gregory, once the flow monitoring was done, a four-year (1989-92) sewer system evaluation program commenced with a budget of $65 million. The information collected from manhole inspections, smoke testing, cleaning and televising, night-time flow isolation and dye water flooding was used to identify where the water was getting into the system. It became one of the largest sanitary sewer surveys ever conducted in the United States.
Annual Service
Agreements
At the same time this program was getting off the ground, another program was instituted called annual service agreements. The Collection System Assessment Section, managed by Gregory, would essentially make a list of work items that needed to be done and take bids for the work. A work order would then be issued to a contractor to perform the rehabilitation work. The group was responsible for the design and construction management of the contracts.
“The first one we entered into was in 1987. It was a cured-in-place annual service agreement for $1.5 million,” said Gregory. “The only repair methods that the city could use were making point repairs or removing and replacing line sections. The idea behind the annual service agreements were that we could add additional repair methods to the city’s repair arsenal. This meant we could just issue a work order to a contractor who could in turn rehab from manhole to manhole. My team would put together a bid proposal that had various line sizes in it and at various steps it would have service reconnects. If point repairs had to be made, we could pay for only those repairs and still have the ability to perform manhole to manhole rehab.”
This type of contract worked so well for the city of Houston that they decided to branch out into other rehabilitation methods, including sliplining and pipebursting.
Gregory wants to continue the work that began in the 80s and take the investigations and rehabilitation work into Houston’s neighborhoods. “We want to go into neighborhoods where we get the most requests for service and evaluate the sewers there and improve them. We won’t just clean the lines, but leave the sewer in better shape than we found it,” said Gregory. “When we were performing infiltration/inflow tests during the program, residents who lived on either side of the line would wonder why we weren’t working on their section. Now we want to go in and address rehab on the entire neighborhood instead of by sections. After we perform hydraulic analysis on the collection system to see if we have the right size pipe serving the neighborhood, then we’ll make an assessment to determine if pipebursting should be used or actually make a relief pipe to make the sewer larger.”
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