The San Diego Metropolitan Wastewater Department has a U.S. EPA Consent Decree requiring rehabilitation of 225 miles of sewer mains and replacement of 130 miles more over the next six years. During 2007, one city bid was to rehabilitate 10 miles of vitrified clay pipe with 1,275 service lateral connections.

Erreca’s Inc. of Lakeside, Calif., won the general contractor bid. It was the first time owner Scott Erreca would install a high-strength, stitch-bonded fabrics liner manufactured by San Diego-based International Pipe Lining Technologies Inc. (IPL). Therefore, IPL assisted as a subcontractor.

“What made this typical CIPP job tough was that 10 percent of the mains were in Norfolk Canyon and 25 percent were in residential back yards,” says IPL project manager Abby De la Cruz. “The remainder was roadwork, but 25 percent involved working at night along the busy Pacific Coast Highway.”

Among the obstacles, De la Cruz and the team faced language barriers, uncooperative homeowners, endangered species restrictions, high-volume traffic, noncompliant drivers, bulldogs, and a cat with four kittens. Despite all that, they completed the job successfully.

Mixed bag

The project involved relining 1,819 feet of 6-inch, 46,577 feet of 8-inch, 2,718 feet of 10-inch, and 742 feet of 12-inch pipe using LightStream fiberglass-reinforced liners. It also included rehabilitating 700 vertical feet of manholes, rebuilding 20, and replacing the grade ring, frame and cover on 40. IPL inspected and cleaned the mains and set up bypass pumping where applicable.

“Cutting through the extensive root intrusion was our biggest cleaning problem,” says De la Cruz. “We even de-rooted 380 laterals.” To prevent roots from entering the relined pipe at the reinstatement, the contract specified service lateral connection liners, which resemble top hats. IPL made them from felt or fiberglass.

“The brim fits flush against the force main, and the cylindrical portion extends four inches into the lateral,” says De la Cruz. A proprietary robot transported and inserted the connections into the laterals, then inflated the liners for curing.

Force mains in Norfolk Canyon slope 20 feet down from grade as they pass beneath the canyon floor, but access to the manholes is along a road at the top of the 30-foot-high canyon ridge. “The difficulty here was maneuvering equipment up and down manholes 50 feet deep,” says De la Cruz.

The area also is home to the endangered California gnatcatcher. “Officials limited us to working four hours in the morning because it was the songbird’s breeding season,” says De la Cruz. “Consequently, it took 14 days instead of five to complete the job.”

Fast curing

LightStream liners were chosen because the system required less setup time and cured faster than steam- or heat-cured lining, enabling IPL to avoid bypass pumping in 60 percent of the work. The average setup to shut-down time including lateral reinstatements was three hours. Most runs were 300 feet between manholes. The longest measured 545 feet.

The equipment’s small footprint and light weight allowed crews to work in restricted areas. “We carry most 8-inch liners by hand, and our equipment is a simple 5-ton winch and an air compressor blower,” says De la Cruz.

When liners arrived, setup took 25 to 30 minutes. Workers gave the pipes a quick jet pass, then pulled the winch cable through the line from the downstream side and tied it to the liner. “The impregnated liner is encased in a plastic foil that eliminates any possibility of contaminating the soil with polyester resin,” says De la Cruz. Two men helped unfold the liner during the pull.

Once the liner was through the pipe and in the downstream manhole, the crew cut it free, leaving a 2-foot extension. They slipped the excess at both ends over a round cylindrical drum called a gate, duct taped it, then winched it down with a ratchet strap for an airtight seal. The gate has a cap with a gasket through which the rope for the EyeBotix UV light chain slides.

Liners were temporarily pressurized at 6 psi to install the 8-foot-long UV light chain. “We remove the cap, pull the chain through, tie it to the rope on the downstream end, slip the cable through the gasket in the cap of the upstream gate, install the cap, and inflate the liner to 6 psi for larger lines or 10 psi for smaller ones,” says De la Cruz. A 3/4-inch cable attached to the light chain has lights, sensors and camera power lines.

Lights, camera, action

At the head of the light chain is a proprietary OpenEye camera with a light on each side. When activated, the winch pulled the light chain rope forward, enabling the crew to inspect the liner for fit and wrinkles. “If the liner’s position isn’t perfect, we can adjust it or, in the worst-case scenario, deflate and reset it,” says De la Cruz.

After the liner passed inspection, a computer inside the IPL truck turned on the eight 400-watt UV light bulbs and regulated the speed of the cable drum as it pulled the light chain back. Sensors determined the speed of its return and the amount of heat generated by the catalyst as the UV light passed. William Barreda operated the UV light-curing process.

“The light activates the photo indicator in the resin that causes the catalyst to heat and cure a 300-foot liner in 40 minutes,” explains De la Cruz. No cool-down time was necessary. IPL designed the EyeBotix reinstatement cutter because nothing on the market was powerful enough to quickly penetrate the fiberglass-reinforced liner, rated at 50,000 psi flexural strength (resistance to bending) and 1.7 million psi flexural modulus (resistance to deflection or deformation).

“With this cutter, lateral reinstatements take five minutes,” says De la Cruz.

Not in my back yard

The city mailed letters in English to homeowners asking them to sign a right-of-way permit allowing IPL to enter their backyards. However, many residents spoke only Spanish and didn’t respond, so the city sent translators to help finalize the permits.

“We mailed a two-week and 24-hour reminder to homeowners and distributed fliers on lining day asking them not to use water,” says De la Cruz. “Nevertheless, they still asked if they could use their water. When we said no, they did it anyway.” Having a bilingual team member explain that water could back up into their homes made no difference.

IPL took pictures before entering properties and when leaving to refute potential homeowner claims that workers damaged something. The biggest residential obstacle was property line fences straddling manholes. Most fences simply were stuck in the ground, but a special team was necessary to remove and replace permanent fencing.

“We’d visit the property two days before the scheduled lining just to make sure the fence was still gone,” says De la Cruz. Other obstacles included an 8-foot-diameter gazebo and an above-ground pool built over manholes.

“We parked our trucks as close to the homeowner’s garage as possible, opened the back yard gate, then pulled the winch, light chain and cutter cables 200 feet to the manhole,” says De la Cruz. Extensive landscaping often made the journey difficult. In five instances, De la Cruz had to assure homeowners – one with four unchained bulldogs – that workers would be gone by a certain time.

During a pipe inspection, the CCTV operator saw a cat with three kittens on the manhole channel. He found another kitten hiding in a nearby lateral. Work stopped until San Diego County Animal Control moved the family to safety.

On the road again

Roadwork was 65 percent of the job, but the section along the Pacific Coast Highway near San Diego Harbor and across from San Diego International Airport raised bypass and traffic-control issues that necessitated working from 8 p.m. to 5 a.m.

Some 70,000 vehicles travel the six-lane highway daily, and it has no emergency parking lanes. The speed limit is an unobserved 55 miles per hour. IPL was responsible for traffic control. Its setup and knockdown stretched the usual three-hour job to five or six. “Our biggest challenge was not being run over by drivers who didn’t comply with our traffic control,” says De la Cruz. IPL closed one lane 500 feet from the work area, and a second lane 200 feet from it.

The success of the nine-month project prompted the city to move any replacement job that didn’t require upsizing into the rehabilitation category. Erreca’s has since won a second contract with the city to rehabilitate 20 miles of sewer mains.