Environmental Divisions of Public Works:

                        Water and Wastewater

 

Water Department

  • Maintain constant supply of potable water for consumption
  • Provide adequate flows/storage for fire protection
  • Maintain infrastructure ~ 48 miles of mains, 450 hydrants, 12 air relief valves, 3 water pump booster stations, four pressure zones, 3 treated water storage tanks (3.0 MG)
  • Operate and maintain facilities (Blue Lake Water Treatment Plant with emergency generator; Ultra Violet Disinfection Facility with emergency generator; Corrosion Control Facility; Indian River Emergency(Non-potable) Supply Source)
  • Preventative maintenance & emergency maintenance
  • Meet all federal and state regulations for water quality, monitoring and reporting to maintain “unfiltered status”
  • Maintain state certified drinking water laboratory for city sampling requirements and on a chargeable basis for private entities e.g. USFS, swimming pools, other municipalities and local contractors
  • Maintain state certified operators at required certification levels for Water Treatment and Water Distribution and plan for succession to maintain future compliance
  • Keep abreast of upcoming regulations and predict system needs

Water Reports - Drinking Water Quality and Watershed Control

 

Background: 

The Water System supplies water to nearly 99% of the population of the City (approximately 3,300 residential and commercial customers).  There are two sources of supply, Blue Lake Reservoir and Indian River.  The Blue Lake source is the primary supply with Indian River serving only as an emergency source.  Blue Lake is an adequate supply for the foreseeable future, however, a secondary water supply needs to be built for use during planned and emergency penstock outages. The water treatment plant receives its water from the penstock which is a series of pipes and tunnels that brings water from Blue Lake to the hydroelectric facility. The penstock should be drained and inspected every five years which will leave the City without a potable drinking supply. The treated water storage capacity should be increased by at least another 1.2 MG, preferably on the Sawmill Creek side of town.  Use of the Indian River water source requires a state approved filtration system or the issuance of a community wide boil water notice due to inadequate treatment of this surface water and limited chlorine contact time before the first customer.  We received an extension for compliance for additional disinfection of Blue Lake water which is required by the federal Long Term 2 Enhanced Surface Water Treatment Rule.  Our extended date to be operational and approved was December 31, 2016; ultra violet (UV) was selected as the most cost effective method.  The UV facility has been operating since late May 2015. We are still waiting on the Final Approval to Operate from the Alaska Department of Environmental Conservation. The UV treatment facility had a cost of $8 million with over 70% of the costs paid by state grants.

 

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 Blue Lake 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 three 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 at the Corrosion Control Facility on Jarvis Street where a 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 $49.45 per unit per month.

 

Future needs for the water systems:

  • Critical Secondary Water Supply.
  • Replacement of aging water mains and associated aboveground and underground infrastructure and treatment equipment. 

 

Wastewater Deapartment

  • Maintain uninterrupted sanitary sewage collection.
  • Maintain infrastructure – 40 miles of collection mains, 41 major, and 37 residential lift stations, 9 permanent and 3 trailer mounted emergency generators.
  • Maintain WWTP equipment and plant performance to operate WW systems within federal operation limits (NPDES permit) to maintain 301 (h) permit status.
  • Preventative and emergency maintenance.
  • Required federal reporting.
  • Follow all applicable federal and state laws.
  • Predict system growth and replacement needs.
  • Maintain state certified operators at required certification levels for Wastewater Treatment and Wastewater Collection and for succession to maintain future compliance.
  • Identify and reduce sources of inflow and infiltration (I&I) into the collection system.
  • Coordinate community annual Household Hazardous Waste Collection events.
  • Provide environmental monitoring & reporting of landfills – e.g. leachate sampling, surveys, methane monitoring (closed Kimsham & APC Landfills, and active Sitka Landfill and Bio-Solids Site).
  • Provide expertise to other City departments for pump and motor rebuilds.
  • Maintain and operate GPIP’s low pressure wastewater collection system to ensure uninterrupted sanitary sewage collection – one duplex lift station, approximately 1 mile of collection mains.

 

Background: 

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 $62.93 per unit per month.

 

Future needs for the wastewater systems:

  • Wastewater Treatment Plant Building Improvements (building envelope, HVAC and electrical systems).
  • Treatment plant equipment replacement.
  • SCADA upgrades.
  • Expanded capacity at the bio-solids disposal area.
  • Continued reduction in I&I, and replacement of aging mains.
  • Lift station replacements.