Even though pipelines run underground, humans must make way on the surface, and that’s what happened in Bridal Falls, British Columbia.

Trans Mountain Corp., which is expanding its crude oil pipeline from Edmonton, Alberta, to Vancouver, British Columbia, was coming through, and an onsite system was in the right of way. It had to be replaced and repositioned, so the company called in Canadian Septic to get the job done.

Because the system was being updated, it was required to meet current standards, says James Stiksma, owner of Canadian Septic based in Langley, British Columbia. Producing wastewater was an eight-room motel, two two-bedroom suites and a three-pad RV park. The motel dated to the 1960s, Stiksma says, but paperwork filed in the 1990s suggested the system had been sized for a two-room addition and 10 RV pads with a daily design flow of 1,369 gpd.

At some point, someone installed a sump pump to collect wastewater from the original eight-room motel and direct it into the system. On paper, the old system was dramatically undersized for what it was handling, Stiksma says. Calculated daily flow for the new system was 3,266 gpd, and the drainfield would be reduced by 33%.

SYSTEM DETAILS

Wastewater flows out of the motel building and the RV pads in 4-inch SDR 35 pipe that joins 6-inch collection lines. These run about 250 feet before entering the first of five concrete tanks connected in series.

The first two tanks collect trash and settle solids. First is a 3,000-gallon tank. Next is a 3,000-gallon two-chamber tank with a Zabel A100 filter (Polylok) in the second chamber at the outlet.

The third tank has a single chamber that holds 3,000 gallons. The fourth tank is two-chambered and holds 2,000 gallons. The 3,000-gallon tank and the first chamber of the 2,000-gallon tank each have Bionest 3000 aerobic treatment units. These use shredded PVC media and fine bubble diffusers fed by five Hiblow HP-100 blowers. The second chamber of the 2,000-gallon tank clarifies water flowing over the partition.

The fifth tank is another 3,000-gallon model that holds the Livewire three-lamp UV disinfection equipment and duplex Liberty FL200 pumps.

There is an option for a sludge return line if future wastewater strength requires it, and Stiksma said his crew plumbed in the ¾-inch line. Activating it would require only installation of a pump.

Effluent is pumped about 200 feet and up about 70 feet through 2-inch Schedule 40 pipe to a six-position Orenco indexing valve that controls dosing of the drainfield.

The field has two beds, each 66 feet by 15 feet, spaced 13 feet apart. Each bed has three separate zones, and each zone contains four 33-foot-long laterals made of 1-inch Schedule 40 pipe. Feed lines from the indexing valve are in the middle of each zone. Orifices (1/8-inch) are spaced at 32 inches along the laterals. Beneath the laterals are 6 inches of clean rounded drain rock. Below the rock is 24 inches of clean coarse sand. On top of the laterals is 12 inches of topsoil.

All tanks came from Galcon Precast on Vancouver Island. An Aquaworx duplex control panel and transducer run the system. Sitksma says he doesn’t use floats because they tend to break. Transducers provide real-time data to the panel on water levels in tanks, he says, and he added that in more than six years of installing transducers he doesn’t recall needing to replace one.

Because the tanks would be under vehicle traffic, the Polylok risers and lids were sleeved with concrete risers and lids from Galcon.

Canadian Septic used its 2022 Kubota KX057-5 mini-excavator and a Kubota SVL 97-2 skid-steer. The excavator is equipped with a Topcon MC-Mobile system that ties sensors mounted on the machine into a tablet computer in the cab. This allows the operator to have a 3D map of the project and know that he is in exactly the right place and that his bucket is at exactly the right depth.

Heavy work on the drainfield and tank excavation was done by Heidelberg Contracting using a pair of Volvo 235 excavators.

WORKING HIGH

The only space for a drainfield was the land about 70 feet above the tanks, Stiksma says. The new drainfield had to be 33% smaller than the old one to avoid infringing on the pipeline right of way, and that was the reason for using a Type 3 treatment system. Under British Columbia rules that’s the highest level of treatment, Stiksma says. A Type 2 system would have required a drainfield roughly 50% larger.

To move drainfield sand and stone up the hill, Canadian Septic employed a conveyor from West Coast Telebelts. That was about a three-day process, Stiksma says. Because the conveyor angle was so steep, material tended to back up. One technician was stationed to push down on material to ensure the conveyor grabbed it, and a second technician cleared buildup at a hopper.

Canadian Septic’s small excavators were used for digging trenches and working around the motel. Replacing the drainlines along the building put technicians in a very tight space. There was only one way in and out, and technicians had to rip out a sidewalk and dig down about 18 inches to fit machines under an overhang. “At one point, I swear, you couldn’t have gotten even a sheet of paper between the roof of the excavator and the gutter of the motel,” Stiksma says.

Another challenge in digging was the presence of cobbles, so everything was set as shallow as possible, Stiksma says. This is not a serious issue in a temperate climate with a shallow frost penetration.

Before installing the drainfield, Stiksma and his wife assembled the indexing valve in the shop. They used sections of clear pipe so any maintenance technician looking at the indexing valve assembly can see whether water is flowing. Lines are also color-coded lines so a maintenance technician can know which clean-out is connected to which indexing valve line.

Because the drainfield uses 2 feet of septic sand, effluent will be very clean even without the UV equipment, Stiksma says. Standards for a Type 3 system in British Columbia require less than 10 mg/L of BOD and TSS, and less than 400 CFU of fecal coliform. The new system meets those standards easily, he says.