About the Sanitary Sewer Utility
Currently, one Assistant Superintendent oversees the treatment facilities, lift stations, the plant laboratory, pretreatment program and the sludge landspreading program. A second Assistant Superintendent oversees the daily duties of the Sewer Department such as closed-circuit televising of the sewer systems, sewer system flushing, all facets of system maintenance, and development and upkeep of sewer-related records. These supervisors and other lead people report to the Wastewater General Superintendent, who in turn is under the Utilities Manager, subject to the authority of the Mayor, Board of Public Works and the Common Council of the City of La Crosse.
The Sanitary Sewer Utility operates and maintains 26 sanitary sewer lift (pumping) stations, about 205 miles of sanitary sewers, and the Isle la Plume wastewater treatment plant that make-up the wastewater collection, conveyance, and treatment system serving the City of La Crosse.
La Crosse accepts and treats sanitary wastes from the Cities of La Crosse and Onalaska, from the Town of Campbell (French Island and Hiawatha Island), from portions of the Town of Shelby (Shelby Sanitary Districts #1 & #2) and, as of July 2008, from the City of La Crescent, MN. Acceptance and treatment of these wastes are done under contract with those entities outside the City limits. As of the end of 2016, current contracts were in-place with the City of La Crescent and Town of Campbell. The City is working with City of Onalaska and Town of Shelby Sanitary District No. 2 to negotiate successor agreements for sewer service.
The first sewers in La Crosse were installed in the 1880's and emptied directly into the Black and Mississippi Rivers. The City’s first treatment plant was built on Isle La Plume in 1936 and provided primary treatment and disinfection. This facility was later expanded in 1958. In 1972 primary treatment capacity was doubled and secondary (biological) treatment facilities were added at a total cost of $3.8 million. The City utilized available 80% Federal and State grants to cover a large portion of the construction costs.
Significant additions and improvements have been completed at the Isle La Plume facility since 1972, including:
Installation of biological phosphorus removal (tertiary treatment) - 1998;
Construction of a sludge storage system - 2000;
Upgrading screening and grit removal systems - 2001.
Rehabilitation of primary clarifiers (settling tanks) – 2004.
Replacement and upgrading of ultraviolet disinfection system – 2004.
Rehabilitation of final clarifiers – 2006.
Rehabilitation of Gravity Thickeners – 2008.
Replacement and upgrading of the aeration system – 2012.
Projects to rehabilitation four digester covers began in 2015. Three of the four covers will be complete as of 2017.
In addition to work at the wastewater treatment plant, projects totaling millions of dollars have been completed to rehabilitate or replace features of the sanitary sewer collection system.
The City’s Sanitary Sewer Utility first went into effect in July of 1991. All properties discharging to the wastewater system, including tax exempt properties, are charged based on either the metered volume of water used or sewage discharged. Charges are calculated to recover the full cost of operating and maintaining the sanitary sewer collection and treatment system. Prior to 1991, these costs had been included in the property tax levy.
The sewer use charge structure includes fixed and volume charges for residential, commercial and industrial discharges, as well as additional charges for high strength wastes (surcharges), and charges for wastes that are trucked and disposed at the wastewater plant by licensed haulers.
Following establishment of the original sewer charges in 1991, sewer rates were increased over three years in the mid- 1990’s to provide adequate funds for capital projects mandated under the City’s discharge permit from DNR. Since completion of those projects in 1996 the Utility has not borrowed any funds for subsequent capital projects. As of 2015, the Sanitary Sewer Utility is debt-free. The Utility maintains both a contingency-reserve fund for approved capital projects and an Equipment Replacement Fund, as required for eligibility for potential future lending programs from the state.
A full review of the sewer user charge system was last completed in 2014 and, based on anticipated capital projects and estimated changes to operating costs over the next 5-years, a rate increase of approximately 10% was recommended by the rate consultant, approved by the Common Council, and implemented as of January 1, 2015. The current structure for sewer rates includes a quarterly fixed charge that varies with meter size, and a volume-based charge of $1.26 per 100 cubic feet (748 gallons). La Crosse’s sewer rates remain among the lowest in Wisconsin.
Typically, a full sewer rate review is completed, as required by sewer service contracts, at least every five years. Following completion of facility planning related to effluent phosphorus compliance (planned completion in 2017), it’s likely that sewer rates will have to be re-evaluated to consider the expected high cost for improving the wastewater plant to meet the new phosphorus standard
The Sewer Utility completed a full facility planning study in 2010 that reviewed and evaluated all current wastewater plant conditions and then considered alternatives for possible plant improvements and enhancements. Although there were no regulatory compliance issues, results of the facility plan identified several areas for possible improvements and recommended several upgrades. Projects identified and recommended through facility planning are prioritized and included as part of the annual Capital Improvement budget process.
The City’s Isle La Plume wastewater treatment facility operates under requirements of a five-year Wisconsin Pollutant Discharge Elimination System (WPDES) permit issued by the Wisconsin DNR. The WPDES permit specifies operating requirements and discharge limits to assure the quality of the water that is discharged to the Mississippi River. The Utility is in the second year of its current five-year WPDES permit
The City’s wastewater facility currently has excess treatment capacity. Flows to the plant averaged about 9.71 million gallons per day (MGD) in 2016, as compared to about 16 MGD in 1990 (before user fees were first implemented). The significant reduction in flow was due to industrial water conservation, City efforts to eliminate clear water inflow and infiltration into the system, and reduced production from City Brewery.
Probably the most significant issue that will affect the City’s wastewater plant in the near future is a change (reduction) in the effluent limitation for Phosphorus (P). The current permit includes a limit for effluent P of 1.0 mg/l. Based on changes in 2010 to the WI Administrative Code, that limit will be reduced to at a level of 0.1 mg/l. Compliance with the new limit is required during the term of the next 5-year permit. Depending on recommendations following completion of facility planning, compliance with a 0.1 mg/l effluent phosphorus limit could require modifications to the treatment plant costing tens of millions of dollars.
The Wastewater Utility operates an Industrial Pretreatment Program that regulates industrial discharges into the wastewater system to assure potentially toxic or other unacceptable wastes do not enter the system. The cost of the Pretreatment Program is recovered through permit fees levied on significant industrial dischargers. Complex state and federal regulations govern the administration of the industrial pretreatment program. In 1989 the City's Industrial Pretreatment tied with Tyler Texas for an award from the U.S. Environmental Protection Agency for the best pretreatment program in the nation for a city in its size category.
The City’s wastewater facility has a long-standing record of operating efficiently, well within permit limits, and discharging very high quality effluent to the Mississippi River. The plant had issue in 2010 that was caused by discharge of high-strength waste from City Brewery, the result of which was violation of WPDES permit limits for three discharge parameters for the month of September. Working closely with the Brewery and DNR, wastewater staff was able to correct the problem such that the wastewater plant was back in full permit compliance in October and has remained in compliance since then. Follow-up work with the Brewery continues to prevent similar problems in the future.
Because the flow of sanitary wastewater to the wastewater plant and lift stations never stops, the treatment facility and lift stations require an extensive back-up system for emergencies such as equipment or power failure. At the wastewater plant, stand-by generators automatically start and supply power to most of the major equipment within 3 seconds of a power outage. Every significant piece of equipment has a back-up. Major sanitary lift stations have dedicated automatic generators on-site to provide power in the event of power outages. Multiple portable generators are also available to provide power to most of the lift stations (sanitary and storm) that are operated and maintained by Utility staff. A comprehensive preventative maintenance program, including an extensive inventory of spare parts and maintenance staff well-trained in emergency repairs, is designed to minimize downtime and damage that could result in emergencies.
Municipal sludge or biosolids are a byproduct of the wastewater treatment process. For calendar year 2016, the City’s total biosolids production was approximately 2,742 dry tons or about 11.9 million gallons of liquid material containing approximately 6% solids. All biosolids generated by the City’s treatment process are currently recycled and applied on approved agricultural fields, generally located to the east, within about a 25 mile radius of La Crosse. The Utility is also working through the permitting process to allow application of biosolids to sites in Minnesota.
As more people move from cities and into rural surroundings, landspreading of municipal biosolids on fields near residential homes can become controversial. In an effort to be good neighbors to all properties potentially impacted by biosolids recycling, since 2006 the Utility has used contracted services to haul and land-apply almost all of La Crosse’s biosolids. The contractor uses specialized equipment to inject the biosolids directly into the ground, thus eliminating odors and concerns related to surface spreading.
Biosolids materials provide a great benefit to the agricultural community. These materials are no-cost, nutrient and moisture-rich fertilizer that save farmers the expense of purchasing commercial products.
Future landspreading restrictions by Towns and changes to regulations related to Phosphorus, could limit or eliminate landspreading of municipal biosolids, and require that these solids are incinerated or disposed of in landfills. Facility planning included biosolids issues as they apply to the La Crosse wastewater plant and evaluated options that will allow the Utility to prepare for the future and react to changes and potentially take advantage of opportunities.
Modern wastewater treatment is a complex process subject to a wide variety of state and federal regulations that are subject to change. Quality standards for effluent and biosolids leaving wastewater treatment plants continue to get more stringent. Although normal operation of the wastewater system is highly automated, it is essential to have skilled employees with specific knowledge related to wastewater. Challenges related to chemistry, hydraulics, microbiology, electronics, mechanics, control systems, computer programming, machining, pumps, protective coatings, agriculture, and specialized equipment repair all come into play at the wastewater plant and/or collection system. The Utility schedules on-call personnel who are available 24 hours per day, year-round, to respond to emergencies at the plant or lift stations, or related to the sewer system.
The sanitary sewer collection system is maintained by the City Sewer Department, a division of the Wastewater Utility. Sewer Department staff cleans and maintains sewers using a variety of specialized equipment; about one-third of the entire sewer system is cleaned every year. The same staff repairs, rebuilds and rehabs catch basins, manholes, and other storm and sanitary sewer structures. The Utility has seen a significant decline in sanitary sewer system backups, largely due to the experience and dedicated efforts of sewer cleaning crews that manage this maintenance program.
Information related to the City’s sewer collection systems has been converted to electronic format, including sewer data and digital maps. This allows easy access and better maintenance of sewer-related information and provides for efficient scheduling and monitoring of sewer cleaning schedules.
Information describing the Sanitary Sewer Utility is included in Chapter 46 of the City’s Municipal Code.