Wastewater and Comprehensive Sewer Plan Summary
Overview of plan
The Wastewater and Comprehensive Sewer Plan for the City of Bloomington was developed as an element of Bloomington's Comprehensive Plan in 2008. The plan describes the historical development of the wastewater system and the characteristics of the existing system. Next, system goals and policies are established which guide decisions about the design, expansion, and maintenance of the system. Projections of wastewater flows thru the year 2030 are made based upon forecasted growth, and the system goals and policies are presented, followed by an implementation strategy. The plan was prepared in accordance with the requirements of the Metropolitan Council's Metropolitan Land Planning Act.
Relationship of wastewater system to Comprehensive Plan elements
The wastewater system of a community is closely tied to its Comprehensive Plan and official controls. The specific land use identified for specific properties in the Comprehensive Plan allows uses that generate typical wastewater flows. The intensity of the use as regulated by the zoning ordinance defines the daily wastewater flow rate. The rate of wastewater flow is utilized to determine the appropriate capacity and facilities needed for the wastewater system.
The City's current Comprehensive Plan was adopted in 2008. The purpose of this Wastewater and Comprehensive Sewer Plan is to provide background information for inclusion into the Sanitary Sewer Element of the Comprehensive Plan to ensure that adequate information is available for future decisions.
Overview of wastewater system
The collection and treatment of sanitary wastewater are primary functions of the City of Bloomington and the Metropolitan Council Environmental Services (MCES). According to the MCES staff, sufficient capacity is available within the plant to serve forecasted growth for the area it serves through the year 2030.
The City of Bloomington's wastewater collection system is available to the majority of existing land uses. Almost 100 percent of Bloomington's current population is connected to the wastewater collection system.
Review of wastewater flows
Bloomington currently generates wastewater flow at an average level of about 9 mgd (million gallons per day). Commercial/industrial users generate approximately 40% of that flow, while residential users generate about 60% of the flow. The table below depicts projected future daily flows.
|Current and Projected Average Daily Wastewater Flow|
|Year||Residential (mgd)||Commercial/Industrial (mgd)||Bloomington Forecast Total Avg. Daily Flow (mgd)||MCES Forecast Total Avg. Daily Flow (mgd)|
Note: Forecasts do not include proposed increased flows from the City of Edina, which are expected to reach about 0.580 additional mgd by 2030.
Wastewater system regulations, ordinances and management practices
The City has adopted a number of practices that are aimed at protecting the quality of water resources within Bloomington and the integrity of the wastewater system. These practices are crucial to the future performance and investment required by the utility system because they represent the manner in which this and previous wastewater plans are implemented.
- The sanitary sewer ordinance requires that properties where domestic or industrial wastewater is produced be connected to the public wastewater system within two years of service availability. Further, the ordinance prescribes the design and manner in which individual connections and use of public sewers are to be made. To limit the amount of inflow into the wastewater system, the ordinance prohibits the flows of storm water, ground water, roof runoff, surface water, unpolluted drainage, unpolluted industrial cooling water, or unpolluted industrial process water into any public sanitary sewer.
- The city zoning regulations determine the specific use and development intensity of individual parcels in the community.
- The city subdivision ordinance requires that property to be developed be served by the municipal wastewater system, and that, all new wastewater facilities required for development must be constructed according to plans approved by the City Engineer.
- The construction of the municipal and MCES wastewater systems and their ongoing operations are financed by: Service Availability Charges (SAC), assessments to properties, and by customer charges that are paid on a regular basis.
- The City has updated its on-site septic system ordinance to comply with current Minnesota Pollution Control Agency (MPCA) requirements.
- The Bloomington Public Works Department Utilities Division is responsible for all maintenance activities associated with the wastewater system. Additionally, the Metropolitan Council contracts with the City for maintenance associated with the interceptor sewer pipes in the City.
Existing system issues
Basic problems that can affect the operation of a wastewater collection system include infiltration, inflow, and blockages. It is important that infiltration and inflow flows be kept to a minimum to maintain pipe capacity and preserve treatment plant capacity. The most common sources of sewer blockages in Bloomington are tree root obstructions and the possibility of solids settling out and collecting within the wastewater collection system as a result of sewer lines flowing at less than design capacity.
Goals, policies and strategies for municipal system
The City of Bloomington has established goals and procedures that govern the capacity and operation of the municipal wastewater system and the relationship of the City's system to regional interceptor and treatment plant facilities. The goals and procedures define the City's policies regarding the relationship of the wastewater system to MCES facilities, planning and development activities, municipal investments, operations, and environmental conditions.
Wastewater System Capital Improvement Plan
In 2006, the City contracted with Black and Veatch to build a Comprehensive Sanitary Sewer System Model and update the recommended improvements needed to accommodate anticipated growth and redevelopment up to the year 2030. City staff has used this computerized model (along with current planning forecasts) to identify twenty-one recommended CIP pipe improvement areas, and seven lift stations with minimal capacities. Upgrades to four of the lift stations, along with five and a half of the pipe project areas, have already been completed. Seven pipe project areas will be monitored for excessive flows and could possibly be removed from the list (if I/I reduction efforts successfully reduce excessive peak flows in the pipes). Eight and a half of the pipe project areas will be scheduled as development stresses the existing pipe capacities. Four of these project areas and one of the lift stations are regional facilities that are owned by the Metropolitan Council Environmental Services (MCES). The City is working with the MCES on capacity upgrades to these facilities.
Information provided by Tim Kampa, Bloomington Civil Engineer - Utilities.