Project Name: Dawson Creek WWTF Upgrade
Location: Dawson Creek, BC
Project Type: Water Reclamation and Reuse
Completion Date: November 2011
The City of Dawson Creek's sole potable water source is the Kiskatinaw River which is often plagued with high turbidity and low summer water levels. Recent growth in the oil and gas sector has led to an increased pressure on the available potable water. The industry normally procures water from the City's potable water supply. Filling stations provide water for use in deep well injection, road dust control and mud preparation. It has been reported that as of 2010 industry was consuming approximately 20% of the City's potable water (Water Canada Magazine - May/June 2010).
To address the increasing demand, the City of Dawson Creek decided to build a Reclaimed Water Treatment Plant (RWTP) producing up to 4000m3/day. This approach would provide the required non-potable water to the oil and gas sector with the added benefit of reducing demand from the domestic water supply.
The alternative of tapping potable water from Peace River to supplement that obtained from Kiskatinaw River was considered. However, due to the large distance between the river and the City's reservoirs, it provided to be too costly to be practical.
A partnership with Shell Canada, gives the company 10 years access to 85% of reclaimed water (Water Canada Magazine-July/August 2010) from the upgraded wastewater treatment plant. The rest of the water is available to industry at a cheaper rate than that of potable water. The city can also use excess reclaimed water for other purposes such as watering parks and sports fields.
In addition to the reuse objective, the City was faced with more stringent effluent requirements for discharging into the environment. A cost effective solution was required to meet these objectives.
NEI's solution to the problem was to design a reliable, simple and low O&M cost process that maximized the existing infrastructure. More importantly, the process would meet BC Municipal Sewage Regulations (MSR) for reclaimed water under the "Unrestricted Public Access" category. In addition, the effluent quality was to be high enough to meet the Canadian Council of Minister of the Environment (CCME) requirements on year round basis.
The SAGR (Submerged Attached Growth Reactor) process was chosen to provide post-lagoon BOD5 and TSS removal to levels of <10mg/L BOD5/TSS. Disk filters following the SAGR process provided final TSS and turbidity polishing to meet the UPA standard. Three SAGR beds were constructed within the footprint of the existing facility, with allowance for a further three beds for future expansion to 6000m3/day.
OPTAER fine bubble diffused aeration had previously been installed at the Dawson Creek WWTP. The diffuser distribution within the cells was designed to optimize both aerobic biodegradation of organic loading and settling of the resultant flocculating biomass. The diffusers are suspended near the bottom of the cells. They provided oxygen and mixing through the rising action of small air bubbles released in the water. The Dawson Creek SAGR has consistently met the design water quality objectives through the first year or operation.