2538201 - Wastewater Treatment Plant Upgrades at Woodcreek Phase 1 of 3

Woodcreek Park is a residential subdivision located approximately 3 km west of Gibsons, British Columbia, within the Sunshine Coast Regional District. The existing wastewater treatment plant (WWTP) and ground dispersal system were constructed in 1999 and serve 74 single family homes. Treatment consists of two (2) septic tanks with biofilters that operate in parallel before combining into a recirculation tank. Water from the recirculation tank is biologically treated by intermittently pumping the water from the recirculation tank to each of four intermittent recirculating sand filter. Eighty percent of the returning water goes back to the recirculation tank and twenty percent goes to the discharge chamber, where it is pumped to the ground disposal field(s). This facility operates with the authority of the Ministry of Environment under Permit No. PE-04183 with a maximum daily discharge rate of 82.4 m3/d.

The Contract is for Phase 1 of improvements for the WWTP involving the construction of a new concrete screening channel followed by a sewage lift station to screen the influent wastewater and transfer it to the septic tanks through new realigned influent pipes. The scope of work for this phase of construction consists of the following:
a) All clearing, grading, excavation, and backfilling required to carry out the described works.
b) Construction of a concrete screening channel.
c) Supply and install a bar screen within the channel along with applicable lifting device.
d) Make changes to realign the inlet pipe to the new bar screen.
e) Supply and install an influent duplex lift station capable of pumping 20gpm at 20ft Total Dynamic Head (TDH) along with its associated control panel.
f) Supply and install a new manhole to replace the existing influent manhole (MH-1).
g) Expose existing inlet pipe connecting the existing manhole to the two (2) septic tanks.
h) Install pipe to connect the new manhole to the screening channel, the screening channel to the influent duplex lift station and the lift station to the new realigned inlet pipe to the septic tanks.
i) Connect the overflow outlet from the influent duplex lift station by gravity to the septic tanks. Note the above-described construction and connections are to be carried out in such a manner as to enable the existing manhole and inlet pipes to continue to transfer influent to the septic tanks until the new works are commissioned and tested.
j) Once the lift station overflow is connected to the septic tanks and commissioned, the influent wastewater can be rerouted from the new manhole to the screening channel and then to the septic tanks through the lift station overflow.

If possible, the Contractor shall perform the described work under low-flow conditions to ensure the screening channel bypass is able to transfer the influent wastewater to the septic tanks.  As the overall construction will be completed under 3 Phases (separate contracts), each of the contractors are required to communicate and coordinate their work with the other two (2) contractors as required.