During the summer 2011, work commenced on a project to clean large diameter sanitary sewer located in Hawaii on the Island of Oahu.
The line to be cleaned was located in a difficult-to-access area. The 6,300 ft of line, 36 in. in diameter, began in the Wailupe Beach Park, then continued along the beach traveling behind multi-million dollar homes, then through the Waialae Country Club golf course and under the Kahala Hotel and Resort, then terminating at the Waialae Beach Park lift station.
Out of the 6,300 ft of line to be cleaned, only approximately four manholes were accessible to cleaning equipment. All additional manholes were trapped between the ocean and multi-million dollar homes. Some manholes were within feet of the ocean and other manholes located in backyards next to swimming pools.
“My favorite manholes were located in the golf course,” said Rusty Nezat, director of Nezat Training and Consulting and operations manager for Jigawon. “Due to the location of these manholes, we had daily access to the Waialae golf course, as well as golf carts and hotdogs.”
Due to the access situation, cleaning by conventional means was not an option, as some of the accessible manholes were more than 3,000 ft apart. Jigawon entered into a working relationship as a subcontractor to EBD to complete the project. This particular sewer cleaning project emerged as part of a larger project being performed by Insituform.
The patented Jigawon sewer cleaning system uses the existing flow of a sewer to remove material and does not require bypass pumping. The system restricts the existing flow inside the line, increasing turbulence within the pipe, suspending the material causing it to move downstream. The system uses low-pressure water at high volumes in order to achieve material suspension during the process. Whereas high-pressure pumping systems use 2,000 psi at 80 gallons a minute (gpm), the Jigawon uses 15 psi at 2,000 gpm. The debris is removed from a selected downstream manhole and the fluid and solid waste is moved into a watertight container. The fluid waste is then drained from the container and deposited back into the downstream sewer line, while the solid waste is captured and dumped at a site suitable for sewer grit and debris. There are two types of Jigawon; Jigawon I and Jigawon II, which operate in the same fashion. Jigawon I is for pipe diameters from 8 in. to 60 in., and the Jigawon II is for diameters of 60 in. and larger.
Once the Jigawon winching machine was set in place at the furthest upstream manhole of the project, crews then proceeded to install and set up the extraction equipment. Due to access, the first extraction process would be set up approximately 3,100 ft from the upstream manhole.
The extraction manhole was located 20 ft from the edge of the beach and 10 ft from the 12th hole sand trap. Once the extraction equipment was set up and tested, crews began to clean. After a period of several days, the Jigawon I was close enough to the extraction point to begin extracting material. Once all the material was collected, the liquid from the extraction boxes was decanted back into the downstream sewer.
Second Half of Project
The second half of the project presented some unique challenges. One manhole was located inside the Kahala hotel and resort, in the restaurant. Then there were the two 90-degree bends back-to-back prior to the line terminating into the lift station. The process was repeated on the next section of sewer to be cleaned, which was approximately 3,200 ft in length. Manholes had to be opened for access where the lines made the 90-degree bends. This proved to be tricky, since more than 800 beach weddings are performed at the Kahala Resort every year. Some weddings were performed with in a 100 ft of these manholes while the cleaning was in progress. Once the two 90-degree bends had been navigated, the Jigawon was slowed down as it approached the extraction manhole. The Jigawon was slowly moved through the last section (between the second 90-degree bend and the lift station), giving the patented extraction system time to remove multiple yards of material and trap the material in the airtight system.
Once the cleaning was completed, all of the piping systems were flushed and chlorinated to ensure there would be no sewer spilled on to the ground as the piping system was broken down and readied to be moved.
Then on to the next project on the Island — the cleaning of the Kipapa Gulch siphon. This siphon was unique in its design. Due to the geographical layout of the Gulch, the siphon was approximately 1,695 ft in length and consisted of three barrels; two were 18 in. in diameter and the third was 20 in.
The upstream junction box was located on the west side of the gulch. The west side of the gulch embankment is on about a 45-degree angle as it extends downhill to a small creek. From the creek bed looking up the east side embankment, it was a sheer cliff. So, starting on the west side, the siphon was laid in stair step fashion until it reached the other side of the creek. This put the depth of the line at approximately 300 ft. At that point, the siphon turned almost straight upward, until it reached the top of embankment on the east side where it made a 90-degree bend and entered into the junction box.
The winching system was installed on the west side, but had to be removed nightly due to past issues with vandalism in the area. The authorities made it known to us that in the past, vehicles and other equipment had been pushed over the edge and into the gulch. The only access to the west side junction box required crews to drive through the historical Kipapa Gulch military storage facility. This section of the gulch is home to 128 concrete bunkers built into the walls of the gulch. Each bunker contains over 4,000 sq ft of floor space. During World War II, these bunkers stored ammunition and it is rumored that nuclear devices were also stored there..
Once the extraction system was put in place the cleaning began. After about three weeks, the cleaning was completed. Each barrel was then inspected using state-of-the-art sonar equipment. The lines proved to be completely free of all material.
Joshua Nezat is media director for Nezat Training and Consulting, which is based in Splendora, Texas.