Sanitary Sewer Master Plan

Overview of plan

The Sanitary Sewer Master Plan for the City of Bloomington was developed as an element of Bloomington's Comprehensive Plan, by Short Elliott Hendrickson (SEH) in April of 1998. 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 2020 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, amended in 1995, and the content requirements for the sewer element included in the Local Planning Handbook prepared by the Metropolitan Council in 1996. Two different levels of emphasis have been utilized to examine the City's sewer system and needs. A Tier I analysis (more general in nature) has been prepared for the southern part of the City and a more extensive Tier II analysis has been prepared for the northern part of the City that aligns the I-494 corridor.

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 is currently in the process of updating its 2020 Comprehensive Plan. It is anticipated that the updated Comprehensive Plan will be adopted at the end of 1998. The purpose of this Sanitary Sewer Policy Plan is to provide background information for inclusion into the Sanitary Sewer Element of the Comprehensive Plan, especially for the Tier II districts 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 2020.

In 1996 and 1997, the City commissioned that two separate studies be prepared to serve as guides in allowing future expansion of commercial and industrial properties. The studies were conducted to determine the effect of potential redevelopment alternatives within these areas on the existing sanitary sewer systems.

Description of existing system

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

Average daily sewage flow has decreased slightly between 1992 and 1996. During that period, there were 493 new sanitary sewer connections made to the City system while the average daily sewage flow decreased by 1.03 million gallons per day. The apparent decrease in average daily flow could be due to: the installation of a new MCES flow meter, City maintenance activities, seasonal fluctuations in rainfall, or a change in customer use patterns.

National Pollutant Discharge Elimination System

National Pollutant Discharge Elimination System (NPDES) permits are issued by the Minnesota Pollution Control Agency (MPCA) to various industrial and governmental users to regulate the manner and performance of wastewater discharges to surface waters. There are 4 NPDES surface water discharge permits active within the City of Bloomington. There are 18 other businesses that are subject to NPDES permits in the City of Bloomington. The businesses must adopt a pollution prevention plan and employ Best Management Practice techniques at the point of discharge. Lastly, in 1997, there were a total of 23 projects in Bloomington that were issued NPDES/SDS permits. NPDES permits and State Disposal System (SDS) permits are issued for projects that are under construction where runoff from the site enters storm water or surface water facilities. Permits issued for these projects extend for the life of the construction project and stipulate that Best Management Practices techniques be followed.

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 recent 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.

2020 Sanitary Sewer System Plan

The 2020 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 2020

The City of Bloomington maintains a sewer and water chapter in their annual Capital Improvements Plan and Program (CIP). It is not anticipated that any significant capital sewer projects will be required if the flow projections included in the computer model are not exceeded.

Information provided by Tim Kampa, Bloomington Civil Engineer - Utilities.