Charleston, South Carolina Distribution Water Main Pipe Repairs

Charleston was experiencing a pair of leaking six-inch DIP water main sections in the West Ashley district, an affluent and historic residential area located on the western banks of the Ashley River. While the city was unknown for coating its potable water pipe infrastructure, the pipes requiring rehabilitation were unlined. Due to this, pinhole leaks allowed water to enter the system continuously. Thea area was known for its high water table due to its proximity to the river and the Atlantic Ocean.

Charleston’s Commissioners of Public Works hired J. Fletcher Creamer & Son (J. Fletcher) as the contractor to rehabilitate the water mains using Warren Environmental’s NSF/ANSI/CAN 61/600 certified potable water epoxy. The epoxy chosen was formulated to seal cracks, inhibit leaks, and prevent the formation of tuberculation. The contractor applied the product using their custom rig equipped with spray-in-place pipe (SIPP) technology.

With numerous underground utilities across this residential area, replacing the existing pipe with an open-cut method was less that desirable. The SIPP rehabilitation method allowed J. Fletcher to maintain a small construction footprint and a safer job site, not requiring the closing of roads.

Scope of Work

The two-week rehabilitation effort comprised several components. First, the water mains had to be evaluated and inspected by closed-circuit television video (CCTV). The existing pipe was reached through two five-foot by seven-foot access pits, minimizing congestion and limiting community disruption. While the access pits were excavated, an above-ground potable water temporary bypass pipe was installed along the curb line on both sides of the street to ensure uninterrupted water service to 32 homes within the affected area.

The contractor designed a comprehensive bypass, which the city approved. The plan incorporated the installation of two- and four-inch diameter pipelines to address both residential service needs and ensure adequate fire protection. The contractor designated a bypass standby representative to be on-call 24/7 in case of issues or damage to the system. Water was supplied to the bypass through hydrants or wet taps to adjacent in-service lines. House services were connected to the bypass with hoses to the resident’s outside hose bib or meter pit, minimizing service interruption. The total footage of the bypass installed was 520 linear feet of two-inch and 2,880 linear feet of four-inch pipelines.

Afterward, a CCTV inspection confirmed the pipe’s condition. Following the condition assessment, it was critical for the pipe’s interior to be properly prepared and cleaned for the epoxy coating system to be effective. This included the removal of all sediment, tuberculation, and debris. Cleaning was conducted using specialized equipment, including drag scrapers drawn back and forth through the pipe to remove hard build-up and tuberculation that may not be removed effectively using water jetting or other techniques. Then, the pipe was water jetted to clear away any remaining scaling, dirt, and film left until it was restored to its original diameter. Free-standing water was removed, but the interior surface did not have to be completely dry, as Warren Environmental’s epoxy adheres to damp surfaces, saving the contractor time to eliminate additional moisture. After cleaning, a final CCTV inspection was conducted to review the condition of the cleaned pipe.

Once the segment was ready for lining, the epoxy material was mixed within the spray rig on the top side near the access pit. The umbilical and spin head were dropped down the pit to the opening of the pipe, where the spin head was inserted. When lining began, the epoxy was pumped through the umbilical and 118 mils of 100% solids epoxy was sprayed to the pipe’s interior in a single coat using centrifugal force. The computerized spray rig controlled the product application providing J. Fletcher with real-time installation data to control the mix ratio, temperature, and the speed at which the spray head was pulled through the pipe. Afterward, the epoxy quickly cured between four to six hours. Coating the water main with epoxy enhanced the structural integrity of the existing infrastructure as a Class III liner per AWWA’s Structural Classifications of Pressure Pipe Linings, with strength modules exceeding ASTM 1743 Class IV classification numbers. The epoxy resolved the existing leaks while preventing future ones and eliminated the development of tuberculation.

Then, the water main was rejoined, sampled, and tested so that the temporary bypass could be removed and existing water service lines reconnected. Two consecutive samples were taken 24 hours apart to ensure the water was safe for potable use. Additional scope of work included the installation of two fire hydrants and four isolation gate valves to enhance water system functionality and safety. Finally, the rehabilitation project concluded with the restoration of roads and landscaping efforts.

Project Challenges

With the rehab project in an affluent residential area with many underground utilities, working around these obstacles was challenging. Additionally, the contractor had to navigate around various storm drainage infrastructures. There were locations where the water main was located behind the curb and in the landscaped yards of the homeowner. Videos were captured before and after the restoration process, meticulously documenting surface conditions. This approach ensured not only an accurate representation of the initial state but also verified that the final restoration surpassed the pre-existing conditions.

Project Successes

City engineers found the application method and epoxy product the ideal solution for their aging water mains. This method and product selected restored their water main without requiring road closures and minimized resident disruptions while navigating the labyrinth of existing underground utilities. SIPP also eliminated unknown assumptions priced into open-cut replacement estimates while saving time through quick cure times of only four to six hours. Moreover, Warren Environmental’s epoxy’s structural enhancement properties added 75 years of new life to their system serving as a protective barrier between the pipe and the water flow.

City engineers found the application method and epoxy product the ideal solution for their aging water mains. This approach effectively restored their pipelines without the need for road closures and minimized disruptions to residents while successfully navigating the complex network of existing underground utilities. The SIPP technology eliminated unknown assumptions priced into open-cut replacement estimates and saved considerable time with the epoxy’s quick cure time of four to six hours. Additionally, Warren Environmental’s epoxy, known for its structural enhancement properties, extended the lifespan of the water system, creating a durable barrier between the pipe and the water flow. The city’s decision to engage a contractor with a proven track record in using potable-safe epoxy alongside SIPP technology was pivotal in ensuring the project’s overall success.