Site 4

Site 6

Site 8

Site 6

CAMBRIDGE BAY, NU - SEWAGE TREATMENT IMPROVEMENTS

CRYOFRONT Kenneth Johnson

Engineer and Planner

Edmonton, Alberta, Canada cryofront@shaw.ca

10

7

9

12

11

6

8

3

5

2

4

1

14

13

SUBMERGED SOLIDS RETENTION BERM

RUNOFF CONTROL AND DIVERSION BERM

SUPPLEMENTAL RETENTION BERM

RETENTION BERM

ISOLATION AND DIVERSION BERM

EXISTING WASTE SITE

The Hamlet of Cambridge Bay is a community of 1500 people in the western region of the Nunavut Territory of Canada. A decade ago, the community and the regulators

had ongoing concerns with the sewage treatment system serving in the community. The existing sewage system was not engineered, and there were a variety of issues,

including community proximity, facility construction, effluent quality, and discharge control.

Cambridge Bay is located along the Northwest Passage in the Kitikmeot Region of Nunavut

Northern communities have inherent issues between sanitation systems and other community activities such as water supply, aviation, and development

The available materials near the community allowed the construction of various earth structures to suit the difference functions associated with the lagoon

Site 8 is located south east of the community – the area has suitable granular material for potential use, but it is a considerable distance from the community

The existing un-engineered sewage lagoon system, was treating the wastewater water to some degree, however, the discharge was not controlled

A planning study was initiated to identify all feasible sites within a 5 km radius of the community; the selection criteria for the sites include “high ground” for solid waste management, a natural

lagoon system, and a natural wetland system - redevelopment of the existing waste site was considered a potential option in addition to a new site

Cambridge Bay has a unique and abundant natural environment in close proximity to the community, along with a interesting history.

The process configuration of the sewage lagoon is a simple retention and seasonal discharge into a natural wetland – sites 1,2, and 3 were eliminated because of proximity issues – capital costs were developed for sites 4 through 8

The design features of the lagoon system included diversion structures for adjacent surface runoff; primary treatment with a rock berm; secondary retention with a low permeability earth berm; a biosolids treatment area; and a limited wetland

The lagoon is discharged seasonally by pumping over the berm structure through the wetland and onto a slope that cascades into the ocean in a location further away from the community - the measured effluent quality is BOD 25 to 50 mg/L; TSS 50 to 100 mg/L and FC 400 to 4000 CFU / 100 mL

The completed lagoon system included a coarse rock berm to control flow from a primary lagoon, and an overflow structure in the retention berm structure

Site 6 is located north east of the community – the area contains several archeological sites – the sewage effluent would discharge into a popular fishing area

Site 4 is located east of the community – the area that is used for summer camping and has a number of cabin sites

After considerable consultation with the community and the Hamlet Council, a decision was made to redevelop the existing site, and “engineer” the sewage treatment areas - the sewage treatment system included primary treatment, secondary retention, and controlled discharge through a limited wetland