The City’s Water System supplies potable water to approximately 99% of the population, serving roughly 3,300 residential and commercial customers. The system has two water sources: Blue Lake Reservoir and Sawmill Creek.
Blue Lake Reservoir is the City’s primary water supply and is considered an adequate source for the foreseeable future. The source currently holds a Filter Avoidance Determination (FAD), which allows the City to operate without conventional filtration due to the high quality of the raw water and watershed protections in place.
Sawmill Creek serves as the secondary and emergency water source. Because Sawmill Creek is not covered under the Filter Avoidance Determination, water drawn from this source must be treated through the City’s Micro-Filtration Plant.
In 2021, the City constructed a Micro-Filtration Plant to serve as a secondary treatment facility. This plant is used during planned or emergency penstock outages, as well as during high turbidity events at Blue Lake. The penstock — a system of pipes and tunnels conveying water from Blue Lake to the hydroelectric facility — must be drained and inspected approximately every five years. During these inspections, Blue Lake is unavailable as a drinking water source, and the City must rely on Sawmill Creek, requiring full treatment through the Micro-Filtration Plant.
The City’s UV treatment facility, which receives water via the penstock from Blue Lake, has been in operation since May 2015. However, the City is still awaiting Final Approval to Operate from the Alaska Department of Environmental Conservation (ADEC). The UV facility was constructed at a cost of approximately $8 million, with more than 70% of the project funded through State grant programs.
To improve system resiliency and redundancy, the City should increase treated water storage capacity by at least 1.2 million gallons (MG), preferably located on the Sawmill Creek side of town. Additional storage would provide operational flexibility during penstock inspections, emergency events, and high turbidity conditions.
The distribution and transmission systems are constructed of mostly ductile iron pipe with a smaller portion of cast iron mains and in recent years, the addition of corrosion resistant high density polyethylene mains. The distribution system includes three storage tanks; the Charteris Street Tank (1.2 million gallons, MG), the Harbor Mt. Tank (0.8 MG) and the Whitcomb Heights Tank (1.0 MG). The distribution mains extend approximately 7 miles north to the Samson Tug & Barge Facility, 5 miles Southeast to Gary Paxton Industrial Park (GPIP) and 2 miles West to the USCG Air Station from the central business district. The connections of the transmission main and the distribution system are near the Sawmill Creek Road and Indian River Road and Jeff Davis St. intersections. Pressures in the lower elevations e.g. the downtown area range from 80 to 85 psi and are correspondingly lower at higher elevations (reducing by approximately ½ psi per foot of elevation rise). There are 3 higher elevation pressure zone booster stations including Wortman Loop, upper Cascade Street, and higher elevations in the Gavin subdivision: the upper section of Hillside Subdivision and Whitcomb Heights. The UV Plant system is rated for 8 million gallons per day (MGD). Current water production averages between 3.1 and 4.2 MGD. A flow rate in excess of 5 MGD is achievable by gravity head from Blue Lake at its new elevation.
Blue Lake water receives treatment at four individual locations; at the Blue Lake Water Treatment Facility near the Blue Lake Hydro and Sawmill Creek where the water is chlorinated for disinfection and the pressure is reduced; at the UV Facility at the GPIP where additional UV disinfection is achieved and fluoride is added for dental health and Micro Filtration if needed. At the Corrosion Control Facility on Jarvis Street sodium carbonate (soda ash) solution is added for pH and alkalinity stabilization to reduce the corrosive nature of the water to household plumbing and comply with the Lead and Copper Rule. Proper disinfection is achieved through managing the chlorine concentration and contact time in the 5+ mile transmission main, the UV light intensity relative to flow and UV transmittance coupled with constant monitoring of other required water quality parameters such as temperature and pH that affect chlorine’s disinfection properties. In the future, aging sections of the distribution system continually need to be replaced.
The unmetered water base rate is $63.12 per unit per month.
The sanitary sewer system collects and treats the sanitary wastewater from nearly 98% of the population of the City (approximately 3000 residential and commercial customers). The average flow (2017) to the wastewater treatment facility is 1.00 million gallons per day (MGD) which has decreased from 1.8 MGD in the 1980's. This reduction is due to removal of extraneous flows (inflow and infiltration, I&I) entering the system through leaks and improper connections. The maximum federally permitted average flow is 1.8 MGD on a monthly basis.
The wastewater treatment plant was built in 1984 and due to the corrosive nature of gases in wastewater along with the age of the infrastructure the wastewater plant is in dire need of repair. The heating and ventilation systems are defunct and air is not flowing in proper directions. Proper air movement is critical for the health of the staff. The corrosive environment has slowly eaten away at electrical components and spare parts are no longer available. The building envelope is rotting from the outside and needs to be replaced.
The sanitary sewer system is operating near target capacity so growth may continue to include more customers at the same rate as the reduction in I&I flows. Great strides have been made in I&I reduction in the past 20 years and more recently with significant improvements: Paxton Manor, Sheldon Jackson College, Biorka/Park Streets, Brady Street, Monastery Street, Etolin Way, Baranof Street, Oja Way, and utility improvement projects.
Due to the geology and topography the wastewater collection system is particularly complex for the community’s size. The collection system includes 41 lift stations containing approximately 85 pumps and related control and alarm systems (more than Anchorage). The collection system extends nearly 6 miles from the central business district to the north to just past the Alaska Marine Lines Barge Facility, 5 miles southeast to SMCIP and 2 miles west to the USCG Air Station. In total there are approximately 40 miles of collection system mains.
The treatment system consists of standard primary treatment unit processes with a deep water marine outfall with a 301(h) discharge waiver from EPA. Normally, sewage treatment systems are required to have secondary treatment but the EPA allows for this waiver for properly operated systems discharging into the ocean. Lime treated, class B-dewatered sludge from the primary treatment is deposited in a specific site at the Sitka Landfill in accordance with EPA guidelines and a DEC landfill permit.
Wastewater base rate is $88.03 per unit per month.
