Willoughby Storm Water Containment System
Township of Langley
One of Gemco’s most valued clients, Qualico Developments Ltd., parent company of Foxridge Homes, needed an innovative solution to control storm water runoff from their future development properties into Yorkson Creek, in the Willoughby neighbourhood in Langley.
A conventional at-grade containment pond was considered, but the cost of purchasing several more acres of highly-priced developable land was a financial hindrance. The solution was to construct an underground system beneath future parkland to the north of the site and connect to the Qualico properties with a large diameter drainage trunk line.
McElhanney, working with ADS Canada, came up with the solution (seen here), and tendered the project in June 2017. Gemco was the successful proponent and started work in September. The containment system, designed to hold 21 million liters of water, was the largest portion of the tender ($6m). The construction included:
- 22,000 m2 pond & playfield footprint
- 50,000 m3 of stripping/excavation and offsite disposal
- 15,000 m3 of excavation and reuse
- 25,000 m3 of clear crushed gravel fill
- 5,000 m3 of sand fill
- Installation of 3,300 Stormtech chambers plus associated piping
The site location also provided two major challenges. It is surrounded by existing residential developments, parks, watercourses, and school sites. Nearly 5,000 truck and trailer visits to the site was required. Gemco designed and implemented traffic control measures to minimize disruptions to vehicles and pedestrians and minimize noise disturbance.
Secondly, the clayey soils that were excavated had a very high silt content that is very weather sensitive and prone to high-sediment run-off, which is continually monitored by Township of Langley staff. The Gemco team used their expertise in environmental protection and best management practices and stayed in compliance with ESC by-laws during the entire project term.
The containment system was completed in 60 days. The balance of the contract, which included over 700 lm of large diameter storm sewer (mostly in existing roadways), an interim playfield, and ancillary works, was completed over Winter 2017/Spring 2018.
The Willoughby Stormwater Containment System is one of the largest of its kind in North America. Gemco’s highly organized team designed and implemented a highly effective and well-coordinated construction plan and completed this project ahead of schedule and for less than the tendered price.
A big thanks to the team at ADS Canada for their technical and logistical excellence!