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Wastewater Facility Planning Studies

Introduction

Wastewater facility planning studies are required by Chapter NR 110 Wisconsin Administrative Code for all "reviewable projects" involving new or modified sewerage systems owned by municipal or other non-industrial entities. The basic purpose of facility planning is to assess the condition of a sewerage system, establish a need for improvement, evaluate options to address system needs, and to identify the cost-effective alternative. The cost-effective alternative is that which results in the expenditure of the minimum total resources costs over the planning period. The total resources costs include monetary costs, environmental and social considerations, and other non-monetary factors. A proposed municipal project demonstrated to be necessary and cost-effective may then be eligible to receive financial assistance from the state Clean Water Fund loan program.

 

The scope of a wastewater facility planning study can vary considerably based on the nature of the problem and type of project. A complete analysis as outlined in s. NR 110.09 Wis. Adm. Code, would be expected for a proposed new facility, whereas the scope of analysis could be reduced for a smaller project such as one involving only one unit process at an existing facility. The Department encourages contact with DNR plan reviewers early on in the planning process to discuss and define an acceptable scope of study.

In some instances, a DNR discharge permit may require a permittee to evaluate a problem and submit a report. This may be in the form of an "Operation and Needs Report" that addresses operational improvements and maintenance needs over a short-term planning period. These reports are typically not the same as a facility plan study conducted for satisfying NR 110 requirements. Any study expected to justify proceeding with construction of a "reviewable project" must be submitted and approved in accordance NR 110 facility planning requirements.

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Ownership and New Wastewater Facility Requirements

To comply with s. NR 110.08, Wis. Adm. Code, any proposal for a new wastewater treatment facility intended to serve residential development must include a demonstration that the proposed facility is necessary, cost-effective and will be owned by a municipal entity. An exception to municipal ownership may be made for new facilities intended to serve existing mobile home parks or condominium developments if the criteria contained in s. NR 110.08(5)(dm) are satisfied. A proposed new wastewater facility may be denied approval if the WDNR determines the facility would not be consistent with its responsibility to protect, maintain and improve the quality and management of the waters of the state.

A proposal for a new wastewater treatment facility to serve isolated non-residential development (such as parks, airports, hospitals, prisons, schools and highway oriented commercial development) must include a demonstration that it is not feasible to connect into an existing sewerage system. The DNR may then approve such a treatment facility provided service is limited to the non-residential development. Municipal ownership is not required for facilities serving isolated non-residential development.

Privately owned or other non-municipal wastewater treatment facilities subject to ch. NR 110 must provide a demonstration of project need and cost-effectiveness in facility plan studies, the same as for municipally owned systems. There are, however, certain facility planning requirements that do not apply to non-municipal systems. Specifically, the requirements of s. NR 110.09(1)(b) 3, 5 and 8, and (2)(b) through (e) and (j) through (m), do not apply to non-municipally owned facilities.

A "municipality" means any city, town, village, county, sanitary district, utility district, public inland lake protection and rehabilitation district, metropolitan sewerage district, or other public entity created pursuant to law and having authority to collect, treat or dispose of sewage.

Wastewater treatment systems that discharge to groundwater via a subsurface infiltration system are defined as "Private Onsite Wastewater Treatment Systems" (POWTS). These systems are regulated by the Department of Commerce with the exception that if the POWTS is defined as "Large" or if the POWTS is owned by a municipality, then certain DNR regulations would also apply. See the guidance for Large POWTS for more information.

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Facility Planning for Collection System Projects

Any proposed reviewable project for a wastewater treatment facility is subject to the facility planning requirements of NR 110.09 including a demonstration of project need and cost-effectiveness. But the facility planning requirements for collection system projects will differ depending on the project type and funding. Any proposal for storage of wastewater, either within sewer lines or in remote storage facilities, is subject to s. NR 110.09 and a facility plan report must be submitted for Department review. For conventional sewer or pump station projects, the facility planning requirement is dependent on whether a state Clean Water Fund (CWF) loan will be sought.

If no CWF loan is involved, the applicant must comply with the requirements of ss. NR110.10 (for sewers) and NR 110.11 (for lift stations). These requirements can be satisfied by completing the standard DNR forms for sewer and lift station construction plan and specification submittals. There is no need to submit a separate facility plan report. But if a CWF loan will be sought for a collection system project, then a separate facility plan must be submitted to demonstrate the proposed project is necessary and cost-effective per s. NR 110.09, Wis. Adm. Code. The facility plan report should be submitted prior to the submittal of construction plans and specifications.

The Clean Water Fund Program is intended to provide financial assistance for projects providing environmental benefits. A collection system project may be eligible if it is necessary to increase conveyance capacity to prevent bypassing, to eliminate excessive clearwater infiltration or inflow, or if necessary to maintain the structural integrity of the system. The loan program is not intended to fund routine maintenance or sewer extensions to new development. Sewer extensions to existing development may be eligible for funding if the project will eliminate adverse environmental or public health impacts associated with the use of private onsite wastewater treatment systems.

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Infiltration and Inflow

The design of any wastewater treatment plant must include consideration of "clear water" that may enter a sewage collection system under wet weather or wet soil conditions, and be transported to the treatment facility. Depending on the scope of a facility planning effort and the extent of clear water flows, separate studies for an "Infiltration /Inflow Analysis" and a "Sewer System Evaluation Survey" (SSES) may be required. The content of these studies is addressed in ss. NR 110.09 (5) and (6), Wis. Adm. Code. A history of frequent sewage bypasses or overflows occurring in the sewerage system may also result in a requirement to prepare I/I or SSES studies.

If infiltration/inflow can be demonstrated to be below certain threshold levels, the Department will consider the I/I to be "non-excessive" and separate I/I or SSES studies will not be required. The infiltration threshold criterion is whether the dry weather flow (the highest base flow plus infiltration occurring for a 7 to 14 day dry weather period during a year) is less than or equal to 120 gallons per capita per day (gpcd). The inflow threshold criterion is whether the maximum daily flow during a storm is less than or equal to 275 gpcd. These criteria are guidelines, not code requirements, and different guidelines or supplemental information may be considered when warranted by specific circumstances.

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Existing Conditions and Design Criteria

A facility plan study for a new facility, or a major upgrade or replacement, should identify a project planning area. A fundamental purpose of the planning area is to enable consideration of alternate sewer service area configurations. The planning area should be large enough to allow examination of possible efficiencies possible in regional systems, including providing service to areas with existing development served by onsite systems. Information should be provided to describe environmental resources, demographics, and land use within the planning and sewer service areas.

Planning and design parameters must be identified for the various alternatives to be considered. This includes service population projections, design flows and waste loadings, and discharge requirements. Additional information is available from the Guidance for Requesting Effluent Limits for Wastewater Facility Planning Studies and Guidance for Wastewater Treatment Facility Design Flow Determinations.

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Identification of Alternatives

The primary objective of facility planning is to identify and evaluate various potential solutions to address wastewater management needs. For new facilities or major upgrades, the alternatives analysis should consider the establishment of the sewer service area and possible connections to existing sewerage systems (regionalization). Facility plans must conform with approved sewer service areas contained in areawide water quality management plans. If a revision to a sewer service area is being proposed, the first step of the planning process will be to seek an amendment to the sewer service area.

Any proposal for a new or upgraded treatment plant may include consideration of different treatment technologies, facility sites, and discharge locations. Discharge may be to surface waters or to groundwater via land application systems such as spray irrigation or rapid infiltration basins. The Department encourages consideration of innovative as well as conventional technologies. If new or innovative methods of treatment are proposed, supplemental performance data may be required to support performance claims for the technology.

The alternatives analysis should include consideration of improving plant performance by improved operation and maintenance measures. In some cases, this may be addressed separately by a "Operation and Needs" study. Phased construction of upgrades may be considered, but all alternatives must still be compared on the basis of a 20-year planning period. When it is proposed to significantly upgrade any portion of an existing facility and to increase plant capacity, the facility planning analysis should also examine the condition of the other processes at the facility. If the other existing processes are not code compliance, or do not perform adequately, the facility plan should examine whether it is necessary and cost-effective to improve them.

All alternatives must be feasible in terms of being implementable from legal, institutional, financial and management standpoints. In some circumstances, local annexation requirements may be associated with a regionalization alternative. Annexation requirements would be evaluated along with project costs and non-monetary factors. In general, the Department does not accept annexation, by itself, as a factor that would necessarily prevent implementation of a project.

After identifying feasible alternatives, they may be systematically compared and screened to identify the principal alternatives to be subjected to the detailed cost analysis. The level of detail in the analysis will depend upon the size and complexity of the project, and the range of cost differences among alternatives.

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Cost-Effective Analysis Methodology

To provide valid monetary cost comparisons, all opportunity costs associated with an alternative over the 20-year planning period should be identified and presented on a total present worth or equivalent uniform annual cost basis. Sunk costs should not be included in the cost-effectiveness analysis because these costs have already been committed regardless of the alternative selected. Sunk costs include investments in existing wastewater facilities and associated lands, outstanding indebtedness and costs for preparing the facilities plan.

Costs should be based on market prices prevailing at the time of the study. Except for energy and land costs, the inflation of costs over the planning period is not allowed. The analysis should account for initial capital costs, future capital costs, annual operation and maintenance costs, and salvage values. Salvage values are determined by assigning a design service life to various components and then calculating the remaining service life and associated value of the component at the end of the planning period. Present worth factors should be based on the current discount rate as established by the WDNR.

Connection fees or other charges should not be included in a cost-effective analysis if they are a method of cost recovery for a sunk cost, or if they only reflect a transfer of payments from one entity to another.

Costs for treatment capacity acquisition from an existing treatment plant may, or may not, be included in the cost-effectiveness analysis depending on specific circumstances. If an existing facility has planned (or excess) capacity to service an area, then no capacity acquisition cost should be included in a cost-effectiveness analysis conducted for connecting that area (the capacity is already available and cost is sunk). But if an existing treatment facility does not have planned (or excess) capacity to service a certain area, then serving that new area would reduce the plant's reserve capacity intended for its remaining service area, and thus shorten its design service life. As a result, the plant would need to be upgraded sooner than what would otherwise be necessary. This represents an actual future cost that should be accounted for in the cost-effective analysis if the plant upgrading would be expected to occur within the 20-year planning period.

Alternatives should be compared on the basis of total present worth or equivalent uniform annual costs. The Department typically considers alternative costs within 10% of each other to be essentially equal in monetary value due to normal cost estimating variability. In some situations, the Department may require the provision of a sensitivity analysis to assess how project costs would vary based on a range of planning assumptions or circumstances.

The facility plan report should contain both a cost-effectiveness analysis and a fiscal impact cost analysis. The fiscal cost analysis will consider grant or loan assistance, financing arrangements, and provide estimates of expected user charges or fees (which should include any existing indebtedness).

The final determination on cost-effectiveness is made with consideration of monetary costs, fiscal impacts, environmental impacts, and possibly other non-monetary considerations.

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Environmental Impacts

To enable a valid comparison of alternatives, the facility plan report should include some environmental impact information on all the alternatives. More specific environmental impact information should be provided for the recommended alternative. See the Resources Impacts Summary Outline for more information.

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Public Involvement

Public involvement is an important aspect of any planning effort for a new or significantly modified sewerage system. Municipalities must conduct at least one public hearing as required by s. NR 110.09(4), Wis. Adm. Code. A copy of the facility plan report should be available for public review before the hearing and at the hearing. Exceptions to the public hearing requirement may be provided if the proposal is for a minor upgrade or if it is a revision to a previously approved project subject to a previous public hearing. Prior to issuing a facility plan approval letter, the Department will issue a news release and typically allow a two-week time period for the provision of public comments.

For major projects, such as constructing both a new collection system and treatment facility, the Department encourages public informational meetings in addition to the required public hearing. A newsletter may also be useful to keep residents informed of ongoing planning developments. It is critical that comprehensive and accurate user cost estimates, planning options, and associated environmental impact information are made available to the public. The Department will consider all received comments as part of the decision making process on a community's proposed cost-effective alternative.

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Facility Plan Revisions

After a facility plan report receives Department approval, there are typically minor design refinements or project changes that occur as the final construction plans and specifications are developed. Minor changes from approved facility plan recommendations should be identified and justified as part of the construction plan and specification review. But if the changes are significant, it may be necessary for the sewerage system owner to prepare and submit a facility plan amendment report to the Department for review under the s. NR 110.09 facility planning rules. The review of an amendment may include a requirement for an additional public hearing. Changes that are normally considered "significant" would involve proposed use of a new site, significant changes to project cost estimates, significant changes to effluent limits or other design parameters, or the discovery of potential environmental impacts not previously identified.

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Further Information

This web page provides a brief overview of the facility planning process. Contact Department plan reviewers to further discuss specific project proposals. Additional information is available from the following links:

Ch. NR 110, Wis. Adm. Code

Outline of the Facility Planning Process

Facility Planning Discount Rate

Sewer Service Area Planning

Agencies Performing Reviews of Sewer Extensions And Providing Sewer Service Area Plan Conformance Letters

DOA Demographic Services Center

Last Revised: Thursday December 28 2006