Growing Pains

Rigorous planning and new technology help bridge the budget gap for Greenwood Metropolitan District
Growing Pains
From left, crew members Roy Hudgens and Brooks Jackson, crew leader David Bell, and crew member Marvin Adams prepare a 2-foot liner repair patch (Stephen’s Technologies) for installation. (Photography by Matt Walsh)

Interested in Cleaning?

Get Cleaning articles, news and videos right in your inbox! Sign up now.

Cleaning + Get Alerts

Growth is generally regarded as a good thing, but few utilities are equipped to take on a nearly instant infrastructure expansion of 900 percent. The Greenwood Metropolitan District (GMD) took the challenge head-on.

Collection system director Wayne Daniel joined the district in Greenwood, S.C., in 1996, as part of a two-man crew responsible for repair and maintenance of 40 miles of sewer trunk line as well as rights-of-way. The equipment roster consisted of a pickup truck and a tractor with a Bush Hog.

The small crew’s responsibilities exploded in 2000 with the acquisition of sewer lines from the City of Greenwood and 36 associated political sub-districts, bringing the system length up to 378 miles. Working to elevate the system to uniform standards has been a decade-long effort that consists of rigorous planning to work within tight budgets, and the adoption of new technologies that promote efficiency, including closed-circuit television (CCTV) inspection cameras and a computerized work order system.

“In the late 1990s, we were seeing that we couldn’t control some of the flows that were negatively affecting the sewage treatment plant,” says Daniel. “The district realized that to effectively address the inflow and infiltration (I&I) issues, the best way was to work with the sub-district commissioners who managed the sewer systems.”

The commissioners, however, signed a petition that resulted in GMD taking ownership of their systems on Jan. 1, 2000. The City of Greenwood simultaneously entered into a maintenance and operations agreement and passed ownership of its system to GMD in March 2004.

The added responsibility led to a dramatic increase in staff — now 15 employees. Fleet requirements expanded to include additional trucks and a new combination sewer truck.

The entire system averaged about 50 years of age, with the oldest sections dating back to 1900. About 80 percent of the lines were made from vitrified clay pipe with the remainder made of ductile iron, PVC and a few miles of concrete.


GIS mapping a priority

Daniel saw inspection, mapping and geographic information system (GIS) tagging of the expanded system as the GMD’s first priority. In 2001, the department bought its first CCTV inspection van.

“We had a lot of issues with that particular camera model,” recalls Daniel. “I think it spent more hours on the road going out for repair than it did with us, so it took a while to be productive. We also have a large number of 4-inch collection lines, and the crawler camera will do only six inches and above so we had to do a lot of tedious and aggravating work with a push cam. That slowed us down a bit.”

The entire camera procedure took until 2007 with coverage gradually ramping up to 60 miles per year. During that time, the GMD focused its rehab efforts on point repairs, targeting obvious problems, any serious conditions recorded by the sewer cams, blockages, complaint calls and reportable sanitary sewer overflows (SSOs).

In the meantime, the district fought a preventive maintenance battle against root intrusion using in-house line cleaning equipment and a chemical foaming program administered by Duke’s Root Control, an outside contractor.

“Our video inspections showed us for certain that roots were a major problem,” says Daniel. “Instead of waiting four to five years before we developed a comprehensive plan, we were buying time by becoming more aggressive on root control on the front end, initially treating and clearing about 12 miles of sewer line per year.”


The great manhole hunt

Part of the initial camera work involved accessing sewer lines through manholes. In 2001, the GMD embarked on the task of mapping and GIS-tagging all of the remaining system manholes using Esri software, which mapped survey-grade Global Positioning System coordinates. The CCTV system was often used to help find the next manhole from the last one mapped. All subgrade manholes were restored back to grade. However, what looked like a simple job expanded into an all out manhole-hunt that took several years to complete.

“There were quite a few of them that were covered and buried over time,” says Daniel. “Some were sodded over, some were paved over and we even found a couple with houses built on top of them that we could no longer reach. By the end of the initial mapping process, three years later, we were confident that we found 99.9 percent of them, although we’re still finding a few today.”

The final tally: more than 8,500 manholes, with about three-quarters of them constructed of brick and mortar. A significant number of them revealed root intrusion, crumbling mortar and heavy I&I, particularly around the seals between the lid and frame interface.

Substantial completion of video inspection of the entire system was achieved in 2010. “We still need to inspect a few lengths of 4-inch line, because the pushrod cameras are limited in range and we don’t own a 4-inch camera crawler,” says Daniel.

In 2008, GMD contracted with Frazier Engineering of Stanley, N.C., for the installation of 12 permanent flowmeters. “These are situated on the larger trunk lines to monitor 10 different basins,” says Marion Boone, director of the district’s dedicated I&I department. “We monitor the sites daily and download the information monthly so we can interpret the data.”

The current maintenance and rehab regimen centers on the findings of the recently completed video work and flow monitoring program, stretching scarce budget dollars to make the greatest difference in the overall system.


Crew dedicated to manhole rehab

A three-person crew is assigned to rehabilitating manholes full-time, four days a week. The crews use QM-1s Restore and Aluminaliner products supplied by Quadex Inc. to reline the manholes.

“After the arduous task of pressure-cleaning the walls, benches and inverts of the manhole to receive the coating, the product is sprayed out of a spinner that we lower down into the manhole,” says Daniel. “It sprays about an inch of cementitious material over the bricks. After we raise the spinner, we then go down and trowel it smooth to make it look better cosmetically.”

The frame and manhole interface are initially bolstered with cementitious grout followed by Flex-Seal, a flexible sealing compound from Sealing Systems Inc. The seal provides improved water resistance and prevents the concrete seal from cracking, particularly in high-traffic areas subject to vibration and movement.

“Last year we completely rehabbed 157 manholes and put our hands on another 604 for other maintenance,” says Daniel.


From roots to repair and replace

For sewer lines, the emphasis has switched from root control to replacement and repair. Line replacement is handled in-house, although about a third of the lines are buried eight feet or deeper. The GMD equipment fleet includes a mini excavator, but the depth of the lines limits the scope of replacement the crews can handle.

“The mini excavator gets the heck worked out of it, but there are tons of repairs on the books that we can’t do, or can’t do quickly enough with a small excavator,” says Daniel. “We’re currently budgeting for a larger excavator that will help us to complete more work faster — all in-house.”

In-house crews replaced about 3,000 feet of sewer line in 2011.

The GMD favors cured-in-place epoxy pipelining for line rehab projects. On larger jobs requiring extensive design, the district uses Frazier Engineering.

“However, every year as we gain experience, we know more of what to look for, and do the homework, including which services need to be reconnected after dye testing, and we’re becoming more confident about designing the jobs ourselves,” says Daniel.

The actual pipe lining is farmed out to two contractors, Southeast Pipe Survey of Patterson, Ga., and Reynolds Inliner, with headquarters in Orleans, Ind.

“We’re not yet ready to bring that work in-house,” says Daniel. “We tend to leave cured-in-place pipe (CIPP) projects near the end of the budget year, so that any money we don’t use can be funneled into that program. Last year we did about $170,000 in CIPP work.”

The district also uses an epoxy short-lining system from Stephen’s Technologies to make trenchless point repairs for projects under 300 feet in length. In-house crews completed 62 short-line repairs in 2011.


Coordinating with pavers

Work is scheduled as much as possible with road maintenance crews from the city, county and the South Carolina Department of Transportation. Although roadwork is planned well in advance, the actual work is sometimes announced with short notice. Little paving work is completed during the winter season, from December to March.

“The paving folks may call us a week before they want to do work on such-and-such a street, and they need to maintain that schedule full-steam ahead to get around the weather,” says Daniel. “It’s touch-and-go as to whether we can work within that tight schedule to adjust our manhole frames and often we’ll have to work right alongside the pavers as they are laying down asphalt.”

Today, the GMD Collection Department employs 20 workers and operates a large fleet of equipment. The equipment garage contains: three Vactor combination sewer trucks; two jetters, one by US Jetting and another by PipeHunter; seven service trucks, all four-wheel drive Ford 350s and 450s; three dump trucks; two backhoes; two tractors with Bush Hogs; and two easement machines.

In-house work is scheduled through an automated computer-based system. After about a dozen years of use, the current software no longer meets the district’s needs, so the GMD is migrating to Cityworks by Azteca Systems Inc.


Incentives for education

Daniel is bullish on employee education. “Every person in the department requires a ‘D’ level Collection System Operator certificate from the South Carolina Voluntary Certification Committee before completing their first year of employment,” he says. “We encourage everyone to reach for ‘A’ level certification and there are financial incentives attached to each level of advancement.”

Improvements in the system are occurring incrementally. Blockage reports were reduced from 172 in 2000 to just 28 in 2011, while reportable SSOs were reduced from 41 to zero during the same period. In 2009, the system’s largest treatment plant processed an average flow of 5.7 mgd. In 2011, that was reduced to 5.2 mgd, with reduced I&I credited with some of the difference.

“Improvements are not coming in leaps and bounds and at times it seems that we’re spending a lot of money to get a little bit of relief, but we’re making inroads and those benefits will start to accumulate over time,” says Daniel. “We’re getting on top of it.”


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.