Wastewater and Comprehensive Sewer Plan

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 sanitary sewer 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 sewer 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 Land Planning Act prepared by the Metropolitan Council.

Relationship of sanitary sewer system to Comprehensive Plan elements

The sanitary sewer 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 sewer flows. The intensity of the use as regulated by the zoning ordinance defines the daily sewer flow rate. The rate of sewer flows is utilized to determine the appropriate capacity and facilities needed for the sanitary sewer 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 sanitary sewer 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 sanitary sewer collection system is available to the majority of existing land uses. Almost 100 percent of Bloomington's current population is connected to the sanitary sewer collection system.

Review of sanitary sewer 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 prospected 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)
2005	5.51	3.55	9.06	9.06
2010	5.82	4.23	10.05	10.26
2015	5.95	4.55	10.50	10.33
2020	6.08	4.88	10.95	10.42
2025	6.14	5.08	11.22	10.52
2030	6.21	5.29	11.49	10.63
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.

Sanitary sewer 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 sanitary sewer 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 sanitary sewer plans are implemented.

The sanitary sewer ordinance requires that properties where domestic or industrial wastewater is produced be connected to the public sanitary sewer 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 sanitary sewer 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 sanitary sewer system, and that, all new sanitary sewer required for development must be constructed according to plans approved by the City Engineer.
The construction of the municipal and MCES sanitary sewer systems and their on-going 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 sanitary sewer 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 sewer 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 sanitary sewer 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 sanitary sewer 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 sanitary sewer system to MCES facilities, planning and development activities, municipal investments, operations, and environmental conditions.

2030 Sanitary Sewer System Plan

The 2030 Sanitary Sewer System Plan has been developed to portray the condition of the Bloomington sanitary sewer system under future flow conditions assuming that the population and employment forecasts are achieved and the operational recommendations of this plan are followed on an annual basis. Population forecast differences between the City Planning Division and the Metropolitan Council should not have an appreciable impact upon the capacities of the local and regional sanitary sewer facilities.

Sanitary sewer system capital improvements to 2030

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. The new model gives City staff the ability to examine modeled flow conditions of any pipe within the public system, at any time over a 24-hour period. The revised recommended improvements included sixteen CIP project areas, and seven lift station upgrades. Upgrade work has been completed at five of the CIP project areas and six of the lift stations. Four of the project areas and one of the lift stations represent 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.