Tank Installation

Case study 10 - Sub Division

Location - Mission,BC

Type of Installation - A residential subdivision designed for 20 modular homes, 5- 4 bedroom homes, 1- 5 bedroom home and a barn with a total volume of 7500 imperial gallons/day to meet the specifications of the Waste Management Act. Go Green was chosen to provide the wastewater treatment system after the developers visited another Go Green site and where unable to detect any smells and did not realize the system was running, it was so quiet.

Design Criteria - The sewage treatment system was designed to meet effluent levels of 10 mg/l of BOD5 and TSS, providing a substantial safety margin over the Waste Management Act requirement of 45mg/l. Five Bore holes were drilled to 3 meters and analyzed for soil profiles by AMEC and Pacific Hydrology. The varying soil profiles and the need for a well to supply water to the development constrained the location of the dispersal field, which was located some 20 meters above the treatment plant on terrain with an average slope of 25 degrees. Two 7.5 horsepower and 1- 5.0 horsepower motor were located underground to pump the effluent from the houses located along a new road to the dispersal field. Extreme care was required in excavations for the dispersal field to maintain the soil cover due on slopes reaching 30 degrees.

Permits - The initial plan for the entire subdivision was submitted to the District of Mission Planning Department. Fisheries and Oceans Canada(DFO) approval in principle was also required to proceed, as several streams on the property were designated as potential fish habitat. Over a year passed before final approval and granting of a discharge permit, due in part to the need for a thorough Environmental Impact Study and to the need for the development to satisfy criteria of hydroelectric, gas and telephone companies.

Solution - The communal water treatment system supplied was three 2000 gallon tanks each equipped with 2 aerator motors, plus a 2000 gallon clarifier tank,sufficient to handle all 26 units. A total of 140,000 plastic media were supplied to provide a minimum media depth of 1.65 meters as specified by the senior engineer at NovaTec Consultants. A culvert was built where the new road crossed a stream. Biodegradable sacks where placed at the end of the culvert, which will promote restoration of the plant growth (see photo).Commissioning of the system will occur after most of the lots are sold.

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