Sewer Service Area Delineation and Planning Process

This section describes what environmental and planning information should be included on SSA boundary maps (including environmentally sensitive areas) and which additional pieces of information should be included in the overall SSA Plan.

Sewer Service Area Maps

Sewer service area maps are the graphic result of the growth strategy for the community's sewered development. The map should delineate the sewer service area boundaries along easily discernable landmarks such as roads, rivers, and property boundaries when possible. Because of the meandering nature of many environmentally sensitive area boundaries, those boundaries are harder to identify. Most, if not all, water quality planning agencies create the sewer service area and environmentally sensitive area boundaries on large scale air photo maps for more critical boundary determinations. Those are available for review at the agency. When the plan map can not include sufficient detail to identify all the boundaries, such as wetlands, this fact should be noted at the appropriate place in the text or maps. For example: "Note - The exact environmentally sensitive area wetland boundaries must be located through a field survey by the Army Corps and/or WDNR staff."

Show the planning area limits

Planning areas generally include all areas within the city, village and sanitary district limits. They should also include adjacent future development areas reasonable for the installation of an extended sanitary sewerage system, and existing development areas that may be experiencing failing onsite septic systems. Planning areas generally extend beyond the existing or future development areas to the nearest quarter section line. All environmentally sensitive areas within the planning area should be delineated.

Show Environmentally Sensitive Areas

Defining environmentally sensitive areas is one of the most important components of your SSA plan. These areas need to be protected from sewered development in order to protect water quality.

The code definition for environmentally sensitive areas is repeated below and should be included in sewer service area plans because, from a natural resource protection perspective, virtually everything we do in sewer service area planning relates to water quality protection and it can not be forgotten; this is our authority.

"Major areas unsuitable for the installation of waste treatment systems because of physical or environmental constraints are to be excluded from the service area. Areas to be considered for exclusion from the sewer service area because of the potential for adverse impacts on the quality of the waters of the state from both point and nonpoint sources of pollution include but are not limited to wetlands, shorelands, floodways and floodplains, steep slopes, highly erodible soils and other limiting soil types, groundwater recharge areas, and other such physical constraints."

NR 121.05(1)(g)2.c.

Wetlands
Floodplains
Shorelands
Steep Slopes and Highly Erodible Soils
Other Limiting Features

Identify Other Conditions

Sewerline siting - Proposed and existing interceptor sewer lines and force mains needed to serve the plan's anticipated 20-year growth should be shown on the sewer service area boundary map. NR 150 requires an environmental assessment for sewers with a diameter of 18" or greater, unless their location is established as part of the approved sewer service area plan. Since the design life of sewers exceeds the 20-year horizon of sewer service area plans, the time horizon for these facilities can be based on a longer time frame than that used for the sewer service area plan. The water quality planning agency should review the design parameters and ultimate service area of the proposed interceptor. Proposed and existing pump/lift stations should also be shown on the map.

Wastewater treatment plant(s) - Show the location of the proposed or currently used plans on sewer service areamaps.

"Infill" Development - The sewer service area map should identify vacant areas appropriate for "infill" development. These areas should be included in the sewer service area residential and commercial/industrial acreage allocations as appropriate.

Discuss the Growth Forecast and Acreage Allocation

• Residential
• Commercial/Industrial

The acreage allocation for sewered development joins the other accumulated components of the planning process to establish the boundary for the community's sewered development. The plan's residential and commercial/industrial acreage allocation for sewered development should consider the following factors:

Acreage Allocation

The acreage allocation is the product of the 20-year population projection and the locally adopted population density standard (number of units per acre). NR 121 requires an acreage allocation based on anticipated residential needs to determine the sewer service area delineation. Industrial/commercial development needs aren't addressed by the code; the acreage allocation for those uses is addressed separately.

Population projections

Population projections used in the sewer service area plan should be derived from data generated by the state Department of Administration - Demographics Services Center.

Population density

Discuss the population density standard adopted in the sewer service area plan. The number of dwelling units per acre can be influenced by zoning ordinances, land availability, and past and anticipated development trends.

"Infill" and "brown fields"

The acreage allocation should include existing developable urban areas already served by utilities and services infrastructure. The area may have been by-passed by development or possibly be an area available for redevelopment; this type of land includes "brownfields".

Brownfields are commercial and industrial lands perceived to be unsuitable for new development due to past site contamination and concerns associated with property owner liabilities. These lands are often tax delinquent and vacant.

Cost-effectiveness

Sewer service area plan development should discuss alternative land development costs as they relate to wastewater treatment and collection system design, avoidance of major environmentally sensitive areas, and housing density standards. The area wastewater facility plan may already include some of this information.

Market factor

A "market factor" to anticipate the affect of local development trends or patterns on the sewer service area plan's acreage allocation is optional. Most plans make no mention, or only brief mention, of a multiplier, alleged to bring the 20-year sewer service areaacreage allocation figure into a greater semblance of the real world real estate marketplace. The principle is that without the market factor, the plan assumes that every property included in the sewer service areaacreage allocation is available and desirable for development. Proponents of a market factor feel a conservative acreage calculation doesn't allow flexibility for over-priced properties, properties not being placed on the market, or buyer whimsy. If department staff feels a market factor is too liberally or unreasonably used, a discussion with the water quality planning agency and the community representatives could appropriately emphasize the pros and cons of application of too liberal an acreage allocation.

Population/Density Comments

Communities are free to determine their own population density standard, which can lend itself to being easily manipulated to obtain a greater residential area acreage allocation. NR 121 specifies the use of local accepted density standards and population projections in the development of a sewer service area acreage allocation.

Ensure Adequate Public Input

Local advisory committee

For nondesignated areas, a local advisory committee must be involved in the planning process. The plan should discuss the advisory committee's involvement in the planning process to assure that local input is present throughout the development of the plan.

By-laws

Optional operating guidelines for the local advisory committee.

Public participation

Discuss the input received through public participation at public hearings and meetings with the local advisory committee (for nondesignated areas). Designated areas must have a minimum of one public hearing on areawide water quality management plans or plan revisions prior to local adoption/denial and prior to the plan being sent to the department for action.

Environmental Assessments

The Environmental Analysis and Review Procedures code (NR 150) specifies that sewer service area plan adoption, updates, or amendments that result in an increase of over 1,000 acres or more than 5 percent increase to the allocated acreage are type II actions which require an environmental assessment (EA) to determine if an Environmental Impact Statement should be developed. If it is determined that the proposal would constitute a major environmental impact, an environmental impact statement will be required. The Department's Regional planner and/or the water quality planning agency responsible for the plan or amendment should help complete and/or participate in the completion of the environmental assessment or impact statement (See also sewerline siting).

Environmentally Sensitive Areas - what are they and how are they protected

Defining environmentally sensitive areas is one of the most important components of your SSA plan. These areas need to be protected from sewered development in order to protect water quality.

The code definition for environmentally sensitive areas is repeated below and should be included in sewer service area plans because, from a natural resource protection perspective, virtually everything we do in sewer service area planning relates to water quality protection and it can not be forgotten; this is our authority.

"Major areas unsuitable for the installation of waste treatment systems because of physical or environmental constraints are to be excluded from the service area. Areas to be considered for exclusion from the sewer service area because of the potential for adverse impacts on the quality of the waters of the state from both point and nonpoint sources of pollution include but are not limited to wetlands, shorelands, floodways and floodplains, steep slopes, highly erodible soils and other limiting soil types, groundwater recharge areas, and other such physical constraints."

NR 121.05(1)(g)2.c.

DNR Guidelines for reviewing SSA Plans and Amendments

The following guidelines represent the minimum criteria that will be used by the department in reviewing and approving of sewer service area plans and amendments. Field investigations will be conducted by department staff where necessary. Results of field investigations will weigh heavily in the final decision on a request for approval.

The local community or designated management agency may utilize more stringent criteria than those established in this guidance. All plans and plan amendments will be reviewed on an individual basis. Unique local conditions or circumstances will be considered in the approval of plans or plan amendments. This guidance will be revised as necessary to reflect changes in state statutes, administrative rules and policies.

Wetlands:

Policy - All wetlands should be excluded from sanitary sewer service areas including wetlands identified in the Wisconsin Wetlands Inventory maps. These lands should be designated environmentally sensitive areas, where sanitary sewer service is prohibited.

Sewer Service Area Plans and Plan Amendments - Plans and plan amendments which would impact a wetland will be evaluated according to the following:

1. The presence or absence of physical alterations in the wetland resulting from human activity. Wetlands which have not been altered should be given high priority for preservation.
2. The availability of reasonable alternatives to development of the wetland. Where alternatives are available, wetlands should be protected from development.
3. The potential impacts of the proposed actions on other scarce natural resources in or outside of the wetland. Consideration should be for protection of the wetland when the area is or has been known to be a habitat for state or federally designated rare, threatened or endangered species; or where it is determined that the wetland type is scarce or rare either statewide or regionally.
4. Presence of or proximity to scientific study areas, sanctuaries and refuges. Direct or indirect adverse impacts in these areas should be evaluated when reviewing an amendment to the plan.
5. Effect on water quality of adjacent stream. Amendments should not result in an adverse effect on an adjacent stream. Such effects include interference with the maintenance of dry season stream flow; increasing sediment, nutrient or other pollutant loading to the stream and decreasing the instream plant and animal habitat conditions.

Floodplains:

Definition - The floodplain is the land calculated to be covered by floodwater during the regional (100-year) flood. The floodplain includes the floodway and the flood fringe.

The floodway is the channel of the river or stream and those portions of the floodplain adjoining the channel required to carry and discharge the flood waters or flood flows associated with the regional flood (NR 116.03, Wis Adm. Code).

Policy - To prevent sewered development in a high hazard area, floodplains should be considered for exclusion from sanitary service areas, and especially the floodway portion of the floodplain should not be included in a sewer service area, except where there is an existing development that must be served.

Sewer Service Area Plans and Plan Amendments - The Department will not approve any plan or plan amendment that is not consistent with an approved county or state floodplain zoning ordinance or which will allow new service to new development in the floodway. In addition, the plans or plan amendments should be evaluated considering the following:

1. Floodwater conveyance capacity. Amendments or plans which would result in a reduction of the floodwater conveyance capacity should be denied unless remedial actions are identified and approved before approval of the amendment or plan. Remedial actions must conform with NR 116.
2. Existing development within the floodway. When there is an existing, lawful development within the floodway, a new plan or plan amendment may include the development within the boundaries of its proposed service area.
3. Storm and flood water storage capacity. Amendments which would result in a reduction in storm and flood water storage capacity should be avoided or remedial actions should be identified.

Shorelands:

Definition - Shorelands are lands within the following distances above the ordinary high-water mark of navigable waters: 1,000 feet from a lake, pond or flowage and 300 feet from a river or stream to the landward side of the floodplain.

Policy - Shorelands represent environmental features which should be given high priority for protection from development, and particularly those shorelands which coincide with wetlands as identified in the Wisconsin Wetlands Inventory maps.

Sewer Service Area Plans and Plan Amendments - The Department will not approve any plan or plan amendment that is not consistent with an approved county or state shoreland zoning ordinance. Additionally, evaluation of plan amendments will consider the following:

1. Potential adverse water quality impacts. In assessing plan amendments the Department will consider adverse impacts upon any of the following:
   1. maintenance of dry season stream flow, or the discharge, recharge or flow of groundwater from a wetland;
   2. filtering or storage of sediments, nutrients or heavy metals that would otherwise drain into navigable waters;
   3. shoreline protection against erosion to reduce the flow of effluent, sediment and nutrients from the shoreland area.
2. Potential adverse effects on habitats. Amendments in which the proposed activity could adversely disrupt fish and wildlife habitat should include protective measures.
3. Storm and flood water storage capacity. Amendments which would result in a reduction of storm and flood water storage capacity should be avoided or remedial actions should be identified.
4. Presence of, or proximity to, scientific study areas, sanctuaries and refuges, or scarce wetland areas. Consideration should be given to direct or indirect adverse impacts in these areas.

Steep Slopes and Highly Erodable Soils:

Definition - This category is defined as any slope or gradient equal to or greater than 12 percent and any soil type occurring on a slope equal to or greater than 12 percent.

Policy - In general, slopes equal to or greater than 12 percent, regardless of the soil type, and which are near surface waters should be excluded from sewered development areas. Steep slopes in combination with other environmental features should also be considered for designation as an environmentally sensitive area.

Sewer Service Areas Plans and Plan Amendments - sewer service area plans should exclude steep slopes greater than 12 percent, which are near a stream, from sanitary sewer service. Where a local construction erosion control ordinance exists, the plan should be consistent with the slope restrictions of the ordinance. Amendments to the sewer service area plan should consider the following.

1. Proximity of the slope to a stream. Amendments for sewered development on steep slopes which would result in direct runoff into a stream should be prohibited, or mitigation measures required for the protection of water quality.
2. Amendments to allow sewered development on slopes should be the most cost-effective alternative and should be consistent with the existing development pattern and locally approved construction erosion control ordinances.

Definition: Other limiting features to development of sewered service include:

• shallow depth to groundwater and/or bedrock (groundwater recharge/discharge areas);

• physical features which may have a significant local or statewide importance such as woodlands or plant stands of rare or endangered species;

• rare or endangered animal habitats;

• historical or archaeologic sites.

This list is open to include any environmental feature that could benefit from protective measures. This definition can include discrete areas of natural resources, and scenic and recreational resource amenities that are critical to maintaining water quality and quantity. They also provide habitat and linkages that are essential for protection of biological diversity and are often associated with rivers and streams.

Policy - Areas that include one or more of the above features should be considered for environmentally sensitive area designation if it represents an integral part of the stream drainage area.

Sewer Service Area Plans and Plan Amendments - In the preparation of service area plans, appropriate state or local offices (e.g., State Historical Society, WDNR Bureau of Endangered Resources) should be contacted to determine if any of these features are present in the planning area. Areas containing these features may be excluded from sanitary sewer service. Plan amendment requests to provide sanitary sewer service to an area with any of these features should be the alternative with the least disruption of the environment and should include remedial measures to provide maximum protection of adjacent water resources.

Variations from code

There are environmentally sensitive areas that do not have a direct relationship to water quality protection, such as SEWRPC's upland woods, and there are areas that normally are not delineated environmentally sensitive yet they potentially have a direct relationship to water quality, such as wellhead protection zones. There is no objection to including these areas in the sewer service area plan's environmentally sensitive areas; in fact their protection is encouraged. But the local community(s) should have the appropriate "conservancy" zoning authority or identify what local mechanisms are available to protect environmentally sensitive areas. NR 121 does not provide authority to require protection of areas that are protected based on criteria other than water quality maintenance.

Parks - The plan should consider including existing and future parks into the environmental corridors system. The community could, at its prerogative, designate other "conservancy zone areas", including parklands, woodlands and historic sites as environmentally sensitive areas.

Local water quality assessment - The assessment can help identify the environmentally sensitive areas to be excluded from the sewer service area.

Why Doesn't the Guidance Use the Popular Term "Environmental Corridor"?

WDNR prefers the term environmentally sensitive areas rather than the term environmental corridors, principally due to the current inconsistent use of the term environmental corridors throughout the state. In addition, the term environment corridor confers the need for the subject resource to be linear or contiguous within the SSA; however, this contiguity is not required for the area to be sensitive and in need of protection under NR121 for maintenance of water quality. Though it is true that many environmentally sensitive areas are associated with rivers or streams, many wetlands, steep slopes and groundwater recharge areas are not necessarily linear. Moreover, if environmentally sensitive upland areas should receive legislative authority for their protection, many of the upland areas would diverge from the linear corridor configuration.

For more information, contact: Lisa Helmuth.