1998 Management Policy

Water Quality Management Policy
Adopted by the Commission
September 14, 1998
Revised: November 1998

Executive Summary

The lakes, rivers, ponds, streams, and wetlands of the Bassett Creek Watershed are an important community asset. These resources supply aesthetic and recreational benefits, in addition to providing wildlife habitat and refuge. The Bassett Creek Water Management Commission recognizes a need to assure adequate water quality in the water bodies in its jurisdiction, and has taken steps to protect these resources.

Phosphorus and suspended sediment are recognized as being particularly detrimental to the health of lakes and streams. As a result, the Commission is requiring measures to reduce the influx of these pollutants to its water bodies. Furthermore, to better plan its strategy, the Commission has identified projected uses and corresponding water quality goals for each of the major water bodies in the watershed.

Wherever possible, the Commission plans to make use of regional treatment facilities to manage water quality. However, in addition to regional treatment, sound water management practices must occur on the local level. To this end, the Commission intends to review plans for construction activities within its jurisdiction to ensure that water quality goals are met.

This document sets forth the Water Quality Management Policy of the Commission. Part I of this document explains the rationale and strategy of the Bassett Creek Water Management Commission in establishing its Water Quality Management Policy. Part II describes the Commissionns review process and its specific requirements for construction activities within the watershed.

Part I: Rationale for the Policy

1. Introduction

When natural areas are urbanized, stormwater runoff from new roads, highways, industries and homes carries pollutants at above-natural rates to adjacent water bodies. Numerous studies have documented the adverse water quality impacts associated with converting land from its native, undisturbed state to urban land uses. Outflow from urbanized areas accelerates the natural eutrophication of our lakes, streams and rivers.

At the same time, an increased population density generally results in an increased appreciation for the many benefits of urban lakes, rivers, wetlands, and streams. This results in strong pressure to mitigate the impacts of urbanization, and to reduce the effects of past water quality degradation.

The Bassett Creek Water Management Commission (Commission) is mandated to manage the water resources of the watershed in order that the beneficial uses of wetlands, lakes, and streams remain available to the community. Such uses may include simple aesthetic appreciation, wildlife observation, swimming, boating, or others.

The Commission recognizes a public need for water quality protection and improvement within its jurisdiction, and accepts water quality management as one of its highest priorities. Part I of this document outlines the CommissionNs objectives with regard to water quality in the Bassett Creek Watershed. Part II gives the standards the Commission has adopted in seeking to meet these objectives. This policy was adopted by the Basset Creek Water Management Commission at its September 14, 1994 meeting. Revisions to the policy were adopted at the Commission=s December 18, 1997 meeting.

2. Objectives and Strategy

The expected use and corresponding desired water quality for a particular water body may be quite different from those of another lake, pond or stream. For example, a large lake in the midst of a residential area may be expected to provide safe and healthful swimming for local citizens. Water quality in this situation would need to be excellent. By contrast, the water quality expectations for a small and relatively neglected pond in a predominantly commercial zone would be lower.

Realizing this distinction between water bodies, the Bassett Creek Water Management Commission found it useful to classify water bodies according to their expected use and corresponding required water quality. Table 1 shows the water quality classifications adopted by the Commission. These classifications rank water bodies by the water quality required to support either current, or desired future uses.

Table 1
Definition of Management Classifications
According to Desired Uses

Level I	Level I water bodies fully support all water-based recreational activities including swimming, scuba diving and snorkeling.
Level II	Level II water bodies are appropriate for all recreational uses except full body contact activities. Recreational activities for these water bodies include: sailboating, water skiing, motorboating, canoeing, wind surfing and jet skiing.
Level III	Level III water bodies will support fishing, aesthetic viewing activities and observing wildlife.
Level IV	Level IV water bodies are water resources generally intended for runoff management (i.e., stormwater detention) and have no significant recreational use values.

It can be seen that Level I water bodies will require the highest water quality. Levels II, III, and IV water bodies require successively lower water quality to support their intended use.

Using the system shown in Table 1, classifications for the major water bodies within the Bassett Creek Watershed were decided upon by the Commissioners. These classifications were based on public input, and resulted from consultation with the staff and elected officials of the cities within the watershed.

For example, water quality goals for Medicine lake were set by the Commission in 1974, after discussions of the effect of the lake's water quality on its recreational use. The water quality that existed in Medicine Lake in 1974 was consistent with the desired use. However, since 1974, the water quality of Medicine Lake has deteriorated and future restorative measures will be needed to reach the water quality goal. The management classifications for Medicine Lake and for the rest of the major water bodies in the Bassett Creek Watershed are shown in Table 2.

Table 2
Management Classifications of
Major Water Bodies in Bassett Creek Watershed

Main Stem	Grimes Pond N. Rice Pond S. Rice Pond Birch Pond Wirth Lake Westwood Lake Bassett Creek (Mississippi River to Medicine Lake)	Level III Level III Level III Level III Level I Level II Level III
North Branch	Lost Lake Northwood Lake Bassett Creek Park Pond	Level II Level II Level III
Medicine Lake Branch	Parker's Lake Turtle Lake Crane Lake Medicine Lake	Level I Level II Level III Level I
Sweeney Branch	W. Ring Pond E. Ring Pond Courtlawn Pond Twin Lake Sweeney Lake	Level III Level III Level III Level I Level I

Level I = Recreational (All Activities)
Level II = Recreational (Non-Body Contact Activities)
Level III = Aesthetic Viewing
Level IV = Runoff Management

After classifying the water bodies of the Bassett Creek Watershed, the Commission set specific water quality goals for each lake or stream, and analysis was made of the steps that would be required to meet these goals. It became clear that the water quality goals could not be met without taking measures to assure adequate water quality in the subwatersheds draining to the water bodies. As a result, watershed management, including review of land development, forms a major component of the management program for the lakes and streams of the Bassett Creek Watershed.

The Commission's watershed management and land development policies are directed mainly at controlling the amount of phosphorus that is carried in the runoff from the watershed. High phosphorus levels in lakes lead to algal proliferation. An abundance of algae reduces the clarity of the water, may result in impairment of fish habitat, and can cause scum and odor problems. Water quality monitoring of Basset Creek waters shows control of phosphorus levels to be the key to controlling algal growth.

Closely related to the reduction of phosphorus loads to the water bodies is the control of suspended sediment inflows. Suspended sediment--fine particles of soil, dust and dirt carried in moving water--results from stormwater runoff from streets and parking lots, and abounds when erosion occurs. This sediment load clouds streams and lakes, thereby disturbing aquatic habitats. It also is a major source of phosphorus, which is frequently bound to the fine particles. As a result, many of the Commission's standards are aimed at preventing or slowing the transport of fine soil, dust and dirt particles into the streams and lakes.

To address its water quality concerns, an overall water quality management plan is currently being developed by the Commission. The plan will identify where regional basins can be developed in the watershed to meet the water quality goals adopted by the Commission. The plan will also estimate the development cost of those regional facilities. After adoption of the water quality plan and the capital improvement plan by the Commission, property owners/developers in the watershed of those regional facilities may be required to contribute to the cost of those regional facilities. Their portion of the cost will be in proportion to their contribution of nutrients to the total contribution of nutrients to the regional facility.

The Commission intends to use regional watershed treatment facilities wherever possible to attain the water quality goals for the watershed. In addition to regional treatment, however, implementation of Best Management Practices (BMPs) will be required on construction sites throughout the watershed. Such practices are seen as particularly important in areas of the watershed where regional detention facilities have not been established or are not feasible.

To encourage water quality protection and the use of BMPs, the Commission intends to review plans for construction activities within the Bassett Creek Watershed in accordance with this policy. Activities within the subwatersheds will be regulated according to the classification (Level I, II, III, etc.) of the receiving water listed in Table 2.

General level-dependent requirements for stormwater treatment are shown in Table 3. The treatments listed are intended to reduce phosphorus, suspended sediment, and other pollutant loads carried by the stormwater runoff.

Table 3
General Requirements for Water Management
According to Management Classification

		Runoff Treatment
Management Classification	Best Management Practices	Sediment-tation	Skimming	Nutrient Removal
Levels I and II (Recreation)	Required	Required	Required	Required
Level III (Aesthetic Viewing)	Required	Required	Required	May be Required
Level IV (Runoff Management)	Required	Not Required	Not Required	Not Required
Wetlands (Types 2-8)	Required	Not Required	Not Required	Not Required

Particular requirements designed to achieve the Commission's water quality goals are outlined in Part II of this document. Part II of this document gives a complete listing of the water quality control standards and design criteria that have been adopted by the Commission. Part II describes:

Which projects will require a submittal for review.

The nature of the review process.

What exhibits will be required in the submittal.

What the standards are for the required "Water Quality Management Plan," in accord with the classification of the receiving water body.

What the standards are for the required Erosion Control Plan.

How a variance from the standards may be applied for.

Part II: Water Quality Management Standards

1. Projects for Which Best Management Practices Must be Considered

a. It is the policy of the Bassett Creek Water Management Commission (Commission) to require that, prior to commencing construction or reconstruction of a site, all persons, municipalities or other agencies proposing improvements, developments, or redevelopments within the Bassett Creek watershed for residential, commercial, industrial, institutional, or public uses shall submit information regarding the project to the Commission in conformity with the requirements of this policy. They shall further secure comments from the Commission regarding the conformance of the project to the policies of the Bassett Creek Water Management Plan. [Note: an NPDES permit for construction activity is required from the Minnesota Pollution Control Agency for projects which disturb one or more acres of area.]

b. A commercial, industrial, institutional or public development is defined as a project involving a site of more than 0.5 acres of land where there is no existing commercial, industrial, institutional or public development. A commercial, industrial, institutional or public expansion/addition is defined as a project involving a site that was partially developed prior to adoption of the Commission's Water Quality Policy (September 14, 1994) and involves grading more than 0.5 acres of land. A commercial, industrial, institutional or public redevelopment is defined as a project involving a site of more than 5 acres of land where the commercial, industrial, institutional, residential or public development currently exists.

c. A residential development is defined as a project involving a site of more than 2 acres and which contains four or more proposed living units. A residential redevelopment is defined as a project involving more than 10 acres where there are four or more existing living units.

d. A road construction or reconstruction project involving a site of more than 5 acres of land for which the site runoff is not currently directed to an onsite or regional treatment facility. This policy results from the Commission=s goal to eliminate direct discharges from roadways to a Level I, II, or III water body, including Bassett Creek.

e. If the Commission has approved a municipal Stormwater Management Plan for a municipality, or for a subwatershed within a municipality, the requirements of this policy which are met by the municipal plan shall be deemed satisfied upon showing compliance with the municipal plan.

2. Review Procedure

a. The Commission will review the developer's submittal only after the applicant demonstrates that the project has received preliminary approval from the municipality indicating compliance with existing municipal plans.

b. The Commission meetings are held the third Thursday of each month. In order for a proposed project to be included on the agenda, plans should be submitted to the Commission staff at least two weeks prior to the meeting date. Complex projects may require additional review time.

c. Upon receipt of a submittal, the Commission staff will review the submittal and prepare recommendations to the Commission. A memorandum describing each project and the staff recommendations will be sent to the Commissioners approximately one week before each meeting.

d. The Commission will review and comment upon the submittal at its regularly scheduled meeting. The Commission will approve, conditionally approve, or reject the submittal. A letter with its comments, including a list of deficiencies or required modifications, will be sent to the municipality and the permit applicant.

3. Required Exhibits for Submittal for Review

A submittal for review shall include two sets of exhibits for Commission review, one set to be returned to the municipality with Commission comments, and one set to be retained in the Commission files. The following exhibits shall be included in a submittal:

a. A set of Project Plans, including at least:

(1) A scale drawing of the site showing property lines and delineation of lands under ownership of the applicant.

(2) Proposed and existing stormwater facilities location, alignment and elevation.

(3) Existing and proposed site contour elevations related to NGVD, 1929 datum.

(4) Construction plans and specifications of all proposed stormwater management facilities.

b. A Runoff Water Quality Management Plan and Computations, signed by a registered professional engineer, and meeting the minimum requirements described in Paragraph 4 of these standards. Pond sizing and average depth calculations must also be provided.

c. A final Erosion Control Plan meeting the requirements of Paragraph 5 of these standards.

d. Completed Application Form and checklist of Best Management Practices.

4. Runoff Water Quality Management Plans--Minimum Standards

A Runoff Water Quality Management Plan shall include the following items:

a. Delineation of the subwatersheds contributing runoff from offsite, and proposed and existing subwatersheds onsite.

b. Delineation of existing onsite wetlands, marshes, and/or floodplain areas.

c. Existing 5-year; and proposed post-development normal, 5-year and 100-year stormwater elevations for the site.

d. Stormwater runoff volume and rate analyses for existing and proposed conditions for 5-year and 100-year storm events.

e. All hydrologic and hydraulic computations necessary to design the proposed stormwater quality management facilities.

f. Documentation indicating conformance with an existing municipal Stormwater Management Plan. If a municipal Plan does not exist, documentation indicating that the municipality has reviewed the project.

5. Best Management Practices--Minimum Standards

a. Best Management Practices--General. A checklist of Best Management Practices such as those shown in Table 4 (see end of this document) shall be submitted demonstrating that, to the maximum extent practical, the plan has incorporated the structural and non-structural BMPs, as described in the book Protecting Water Quality in Urban Areas (Minnesota Pollution Control Agency, 1989). A list of other BMPs is given in Table 5 to illustrate the range of practices that minimize the adverse effects of stormwater runoff on receiving waters.

b. Best Management Practices--Expansion/Addition Projects. For commercial, industrial, institutional or public expansion/addition projects, the Commission realizes that existing development may limit the type of best management practices that can be implemented for the entire site. The most desirable best management practice is to construct a permanent wet detention basin to serve the entire site. At a minimum, a wet detention basin must be constructed to serve the expansion/addition and, if applicable, the increased contributing drainage area of the basin. Other appropriate best management practices will be required for the existing development if wet detention for the increased contributing drainage area is not practical. The Commission will work with the project applicant to assist with determining the appropriate temporary and permanent best management practices to implement for the project.

c. Best Management Practices--Road Projects. Best management practices must be considered to improve the quality of stormwater runoff from road construction and reconstruction projects. The most desirable best management practice is the construction of a permanent wet detention basin, if possible. The Commission realizes that existing development and right-of-way constraints will limit the type of best management practices that can be implemented. At a minimum, temporary measures will be required to address erosion and sediment control during construction. The Commission will work with the project applicant to assist with determining the appropriate temporary and permanent best management practices to implement for the project. The project applicant must submit a description of the evaluation process used to identify feasible best management practices to be implemented on the project.

Examples of applicable construction (temporary) best management practices include, but are not limited to:

Silt fence/hay bales

Temporary diversions

Temporary stream crossings

Catch basin inlet protection

Examples of permanent best management practices include, but are not limited to:

Detention basins (wet and dry); these can be formed along ditches through the use of permeable check dams or weirs

Infiltration

Vegetated swales

Slope erosion protection

Streambank protection

Filter strips

Infiltration trenches

Grit chambers or sump manholes are another possible best management practice for capturing sediment. They are less desirable best management practices because of the need for frequent inspection and cleaning at least twice per year to be effective. If either is proposed to be used, the project applicant will be required to submit a maintenance schedule.

6. General Ponding Requirements

In general, it is the Commission's policy to manage its water resources using the regional detention basin concept. However, where regional basins have not been constructed or cannot be developed, sound water quality management requires the use of onsite detention basins or other features to meet water quality goals established for Bassett Creek watershed receiving water bodies.

a. Natural or excavated low areas will be used for the detention basins. Generally accepted reservoir routing procedures using critical duration runoff events shall be used for design of these areas and outlets.

b. The size and design of the onsite detention basin will depend on the receiving water body's management category (see Table 2) and flow conveyance capacity, the quantity of impervious surface within the development, and the degree to which onsite infiltration of runoff is encouraged. Onsite detention basins shall be designed based on the following:

(1) Water Quality Goals

Detention basin shall achieve pollutant removal efficiencies equal to or greater than those obtained by implementing the criteria set forth by the Nationwide Urban Runoff Program (NURP) and Protecting Water Quality in Urban Areas (MPCA, 1989) with specific consideration to the receiving body water quality goals. Design of onsite detention basins will depend, to some extent, on the Commission's water quality goals for the receiving water. For example, if the receiving water body has a Level I water quality goal, the detention basin discharging to that lake or stream must achieve high pollutant removal efficiencies. A Level IV goal, by contrast, would not demand that efficiencies be as high.

(2) Water Quantity Goals--Flow Conveyance Capacity

Onsite detention basins shall avoid or minimize increases in predevelopment runoff rates to the greatest extent practical. The capacity of the receiving body to convey and/or store the runoff shall also be considered so as to not adversely affect water levels off the site.

(3) Alternatives to Onsite Ponds

Alternative water quality management features may be used where onsite ponds are not feasible. Alternative features must be designed to provide water quality benefits that equal or exceed design criteria outlined in existing Commission policies.

7. Water Quality Pond Design Criteria

Following is the detention basin design criteria that must be met for each water quality management classification (Levels I, II, III, etc.) based on the receiving water body. See Table 2 to determine the water quality management classification of the receiving water body.

a. Level I Water Bodies and Streams

(1) The permanent pool ("dead storage") volume below the principal spillway (normal outlet) shall be greater than or equal to the runoff volume from a 2.5-inch, 24-hour storm over the project site, assuming full development. Under special conditions, such as expansions to existing water quality ponds, the entire contributing drainage area will need to be considered in computing the dead storage volume, assuming full development of the drainage area.

(2) The permanent pool average depth (basin volume/basin surface area) shall be > 4 feet, with a maximum depth of < 10 feet. For small ponds (less than 3 acre-feet in volume) average depth shall be > 3 feet, with a maximum depth of < 10 feet. An "effective average depth" (basin "effective volume"/basin "effective surface area") may be calculated for ponds that include basin shelves. The "effective volume" and "effective surface area" are computed by extending the basin sideslopes below the basin shelf, vertically, to the water surface.

(3) An emergency overflow (emergency outlet) must be in place and adequate to accommodate the 100-year frequency critical duration rainfall event.

(4) Basin side slopes above the normal water level shall be no steeper than 3:1 when possible, and preferably flatter. A basin shelf with a minimum width of 10 feet and 1 foot deep below the normal water level is recommended to enhance wildlife habitat, reduce potential safety hazards, and improve access for long-term maintenance.

(5) To prevent short-circuiting, the distance between the major inlets and normal outlet shall be maximized.

(6) The flood pool ("live storage") volume above the principal spillway shall be such that the peak discharge rate from the 5-year frequency, critical duration storm does not exceed the peak discharge for a similar storm under predevelopment conditions.

(7) Extended detention of runoff from the more frequent (1-year to 5-year) storms shall be achieved through a principal spillway design which shall include a perforated vertical riser, small orifice outlets, or a compound weir.

(8) The design must include effective energy dissipation devices that reduce outlet velocities to 4 fps or less. These outlets shall consist of stilling basins or other such devices that prevent erosion at all stormwater outfalls into the detention basin, and at the basin outlet. Storm sewer outfalls must extend to the detention basin or other receiving water body and must discharge at or below its normal water elevation.

(9) Trash and floatable debris skimming devices shall be placed on the outlet of all onsite detention basins to provide treatment up to the critical duration 5-year storm event. Submerged inlets, permanent baffled weirs or similar devices may be employed. Timber baffled weirs are discouraged. Velocities through the devices shall be less than 0.5 fps. The top of submerged inlets shall be at least one foot below the water surface.

(10) During construction of the basin, care shall be taken to prevent the discharge of waterborne sediments to downstream water bodies.

b. Level II Water Bodies and Streams

(1) The permanent pool (dead storage) volume below the principal spillway (normal outlet) shall be greater than or equal to the runoff volume from a 2.0-inch, 24-hour storm over the project site, assuming full development. Under special conditions, such as expansions to existing water quality ponds, the entire contributing drainage area will need to be considered in computing the dead storage volume, assuming full development of the area.

(2) All other requirements as listed above for Level I water bodies.

c. Level III Water Bodies and Streams

(1) The permanent pool ("dead storage") volume below the principal spillway (normal outlet) shall be greater than or equal to the runoff volume from a 1.5-inch, 24-hour storm over the project site, assuming full development. Under special conditions, such as expansions to existing water quality ponds, the entire contributing drainage area will need to be considered in computing the dead storage volume, assuming full development of the area.

(2) All other requirements as listed above for Level I water bodies.

d. Level IV Water Bodies and Streams

(1) Energy dissipation devices as described for Level I water bodies, and any and all other practical measures needed to maintain the function and character of the Level IV water body.

e. Wetlands (Type 2-8)

(1) Energy dissipation devices as described for Level I water bodies, and any and all other practical measures needed to maintain the function and character of the wetland.

8. Erosion Control Plans--Minimum Standards

a. During construction where grading involves more than 200 cubic yards of cut or fill, or disturbs more than 10,000 square feet, an Erosion Control Plan shall meet the standards given in the Erosion and Sediment Control Manual (Hennepin County Conservation District, 1989) and Protecting Water Quality in Urban Areas (MPCA, 1989).

b. Erosion control plans submitted for review shall show proposed methods of retaining waterborne-sediments onsite during the period of construction, and shall specify methods and schedules to determine how the site will be restored, covered, or revegetated after construction.

c. In addition, the project applicant shall:

(1) Provide specific measures to control erosion based on the grade and length of the slopes on the site, as follows:

(a) Silt fences shall be placed along the toe of the slopes that have a grade of less than 3 percent and are less than 400 feet long from top to toe. The silt fences shall be supported by sturdy metal or wooden posts at intervals of 4 feet or less.

(b) Flow lengths up-slope from each silt fence shall not exceed 400 feet for slopes that have a grade of less than 3 percent.

(c) Silt fences shall be placed along the toe of the slopes that have a grade of 3 to 10 percent and are less than 200 feet long from top to toe. These fences shall be supported by sturdy metal or wooden posts at intervals of 4 feet or less.

(d) Flow lengths up-slope from each silt fence shall not exceed 200 feet for slopes that have a grade of 3 to 10 percent.

(e) Diversion channels or dikes and pipes shall be provided to intercept all drainage at the top of slopes that have a grade of more than 10 percent and are less than 100 feet long from top to toe. Silt fence shall be placed along the toe of said slopes, and shall be supported by sturdy metal or wooden posts at intervals of 4 feet or less.

(f) Diversion channels or dikes and pipes shall be provided to intercept all drainage at the top of slopes that have grades of more than 10 percent. Also, diversion channels or diked terraces and pipes shall be provided across said slopes if needed to ensure that the maximum flow length does not exceed 100 feet. Silt fence shall be placed along the toe of said slopes, and shall be supported by sturdy metal or wooden posts at intervals of 4 feet or less.

(2) Require that silt fences or hay bales, staked with at least two sturdy metal or wooden posts per bail, be installed around each catch basin inlet on the site and that this barrier remain in place until pavement surfaces have been installed.

(3) Ensure that flows from diversion channels or pipes are routed to sedimentation basins or appropriate energy dissipators in order to prevent transport of sediment to outflow conveyors and to prevent erosion and sedimentation when runoff flows into the conveyors.

(4) Provide that site-access roads be graded or otherwise protected with silt fences, diversion channels or dikes and pipes to prevent sediment from leaving the site via the access roads. Each site-access road shall have coarse aggregate filter berms with a minimum height of 2 feet above the adjacent roadway and with maximum side slopes of 4:1.

(5) Require that soils tracked from the site by motor vehicles be cleaned daily (or more frequently, as necessary) from paved roadway surfaces throughout the duration of construction.

(6) Assure that silt fences and diversion channels or dikes and pipes be deployed and maintained for the duration of site construction. If construction operations interfere with these control measures, the silt fences, diversion channels or dikes and pipes may be removed or altered as needed but shall be restored to serve their intended function at the end of each day.

(7) Specify that disturbed areas be revegetated or mulched permanently or temporarily if it can be reasonably anticipated that significant additional grading will not occur within 30 calendar days. A schedule of significant grading work will be required as part of the erosion and sedimentation control plan.

(8) Require that temporary or permanent mulch be disc-anchored and applied at a uniform rate of not less than 2 tons per acre.

(9) Provide a temporary vegetative cover consisting of a suitable, fast-growing, dense grass-seed mix spread at 1.5 times the usual rate per acre. If temporary cover is to remain in place beyond the present growing season, two-thirds of the seed mix shall be composed of perennial grasses.

(10) Provide a 4-foot wide sodded area along the curb line of all streets adjacent to the site and along all property boundaries where runoff could leave the site.

(11) Specify a permanent vegetation cover consisting of sod, a suitable grass-seed mixture, or a combination thereof. Seeded areas shall be either mulched or covered by fibrous blankets to protect seeds and limit erosion.

(12) Provide temporary onsite sedimentation basins whenever other erosion and sedimentation control practices are inadequate. Onsite detention basins shall be designed to achieve pollutant removal efficiencies equal to or greater than those obtained by implementing the criteria set forth by the Nationwide Urban Runoff Program (NURP), and Protecting Water Quality in Urban Areas (MPCA, 1989).

9. Variances from the Water Quality Management Policy

a. Applications for variances shall be filed with the City where the property being developed, redeveloped, or retrofitted is located and shall state the exceptional conditions of the property and the peculiar and practical difficulties claimed as a basis for a variance. The applicant shall state on the application the reasons for requesting the variances, in accordance with all the requirements set forth in Section (c) below.

b. All applications for variances shall be referred by the City to the Bassett Creek Water Management Commission's Engineer, and shall be reviewed by the Commission. In reviewing the application, the Commission shall take into consideration the criteria, standards, and goals for maintaining and improving the quality of the watershed's public waters.

To address the applicant's hardship or special situation, the Commission may grant the variance, contingent upon conditions that the Commission may set forth. Alternatively, the Commission may deny the request and set forth reasons for the denial.

c. In granting variances, the Commission shall make a finding showing that all of the following conditions exist:

(1) There are special circumstances or conditions affecting the property such that the strict application of the provisions of these standards and criteria would deprive the applicant of the reasonable use of its land.

(2) The variance is necessary for the preservation and enjoyment of a substantial property right of the applicant.

(3) The granting of the variance will not be detrimental to the public welfare or injurious to the other property in the territory in which the property is situated.

(4) In applications relating to a use in the floodplain or within the management envelope set forth in the management plan, the variance shall not allow a lower degree of flood protection than the flood protection elevation stated in the management standards.

(5) The granting of the variance will not be contrary to the intent of taking all reasonable and practical steps to improve water quality within the watershed.

10. Definitions

a. Road construction or reconstruction projects include any project which results in the complete removal of the road surface, exposing the base, and/or removal of the vegetated surface within the road right-of-way. Examples include road widening projects, ditch work, road replacement and utility installation. Road overlay projects and road resurfacing projects which do not disturb the road base will not be covered by the requirements of this policy.

b. Commercial, industrial, institutional or public development projects typically result in larger areas of impervious surface, typically in the range of 60 to 80 percent imperviousness. Examples of these developments include shopping malls, stores, schools, hospitals, and warehouses.

c. Residential development projects typically result in smaller areas of impervious surface, typically in the range of 25 to 60 percent imperviousness. Examples of these projects include single family home construction, townhome construction and apartment building construction.

d. Commercial, industrial, institutional or public expansion/addition projects are additions to existing projects for which approval of the existing project was obtained prior to adoption of this water quality policy. Examples of such projects include parking lot expansions/additions and building expansions/additions.

e. Best Management Practices are the structural, non-structural, and institutional controls used to improve the quality of stormwater runoff. Tables 4 and 5 at the end of this section provide examples of common best management practices. Additional best management practices may be found in Protecting Water Quality in Urban Areas (MPCA, 1989).

f. Onsite or regional treatment facility is a stormwater treatment basin designed to treat the stormwater runoff generated from either the project site (onsite) or an area larger than the project site (regional).

g. Complex projects include projects that are 40 acres or more, controversial, involve more than one property owner, require detailed hydrologic or hydraulic modeling, require vast changes to infrastructure (such as stormwater systems), include many wetland impacts, require extensive environmental review, or involve many different land uses within the same development project.

h. Stormwater (management) facilities include storm sewer pipes, ditches, ponds, infiltration basins, etc.

i. Critical duration runoff: Generally accepted reservoir routing procedures using critical duration runoff events refers to the hydrologic methods, usually computer models, used to determine flowrates and flood levels resulting from stormwater runoff events. The event which results in the highest flood level or flowrate is the critical duration event. Examples of such methods include TR-20, Hydrocad, SWMM, HEC-1 and other approved watershed models.

Table 4
Checklist of Common
Best Management Practices (BMPs)
For Development or Re-Development

Description of BMP	Was BMP Used in Project?	Location Used or Basis for Nonusage:
Discharge Elimination BMPs
1. Reduce area of impervious surface (pavement, roofs, etc.)
2. French drains and subsurface drains
3. Infiltration trench and dry well
4. Exfiltration trench
5. Porous pavement
6. Retention (infiltration) basin
Stormwater BMPs
7. Detention Basin with outlet protection
8. Extended detention basin
9. Wetland treatment area
10. Parking lot/rooftop runoff storage with outlet protection
11. Grit chambers/manholes
12. Diversion channel
Floatable/Oil Removal BMPs
13. Floatable skimmer
14. Parking lot oil/grease separators
Sediment Control BMPs
15. Riprap or other storm drain outlet protection
16. Storm drain inlet protection
17. Slope stabilization and erosion control measures
18. Vegetated swale
Nonstructural BMPs
19. Street sweeping
20. Fertilizer management
21. Other (describe):

Table 5
Suggested Best Management Practices

Institutional Source Controls

No Littering Ordinance
Pet Feces Removal Ordinance
Chemical Use/Storage Ordinance
Recycling Programs
Public Education Programs
Vacant Lot Cleanup Ordinance
Spill Prevention Ordinance
Nonstructural Source Controls
Program to Prevent Illicit Discharges
Street Sweeping
Cleaning of Storm Drains

Minor Structural Source Controls

Diversion Channels
Grass Swales
Natural Channels to Reduce Erosion
Vegetative Controls on Exposed Soils
Storm Sewer Outlet Protection
Slope Stabilization and Erosion Control Measures
Riprap Protection

Minor Structural Discharge Elimination Methods

Development and Maintenance of Recharge Areas
Development and Maintenance of Porous Pavement
French Drains and Infiltration Trench

Moderate Structural Controls for Floatables/Oils Removal

Development and Maintenance of Parking Lot Oil/Grease Separators
Development and Maintenance of Parking Lot and Rooftop Runoff Storage with Outlet Protection

Major Structural Controls for Floatables/Oils Removal

Detention Basin with Outlet Skimmer
Wetlands Treatment Area

Major Structural Controls for Floatables, Metals, Microorganisms, and Nutrient Removal

Lime Precipitation, Filters, and Chlorination/Dechlorination to Detention Basins
Lime Precipitation, Chlorination/Dechlorination to Wetlands