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Discuss Minnehaha Creek Watershed District Minor Plan AmendmentCITY OF CgANHASSEN 7700 Market Boulevard PO Box 147 Chanhassen, MN 55317 Administration Phone: 952.227.1100 Fax: 952.2271110 Building Inspections Phone: 952.227.1180 Fax: 952.227,1190 Engineering Phone: 952.227.1160 Fax: 952.227.1170 Finance Phone: 952.227.1140 Fax: 952.227.1110 Park & Recreation Phone: 952.227.1120 Fax: 952.227.1110 Recreation Center 2310 Coulter Boulevard Phone: 952.227.1400 Fax: 952.227.1404 Planning & Natural Resources Phone: 952.227.1130 Fax: 952.227,1110 Public Works 1591 Park Road Phone: 952.227.1300 Fax: 952.227.1310 Senior Center Phone: 952.227.1125 Fax: 952.227.1110 Web Site www.ci.chanhassen.mn.us MEMORANDUM TO: Todd Gerhardt, City Manager FROM: Terry Jeffery, Water Resources Coordinator +� DATE: May 9, 2011 106 SUBJ: Discussion of Minnehaha Creek Watershed District Minor Plan Amendment As It Pertains To Existing Local Controls and Surface Water Management Plan v PROPOSED MOTION This item is being presented for information purposes only. Staff will bring necessary plan and code amendments for review(s) and public hearings if needed. No action is needed or expected at this time. BACKGROUND Minnesota Rules Chapter 10313.231 requires that "A watershed management plan is required for all minor watershed units wholly or partly within the metropolitan area." Subdivision 3 of the same section states that "Where a watershed management organization exists, the plan for the watershed must be prepared and adopted by the organization." Minnesota Rules Chapter 10313.235 states that "After a watershed plan is approved and adopted, or amended, pursuant to section 10313.231 the local government units having land use planning and regulatory responsibility for territory within the watershed shall prepare or cause to be prepared a local water management plan, capital improvement plan, and official controls as necessary to bring local water management into conformance with the watershed plan within the time period prescribed in the implementation program of the watershed plan and, as necessary, shall prepare or cause to be prepared amendments to the local comprehensive plan." The following timeline describes the coincidence of the City's plan with the District's plan: • March 29, 2006: The City of Chanhassen submitted their Second Generation Local Surface Water Management Plan (SWMP) for review to all review agencies including the Minnehaha Creek Watershed District (MCWD). May 12, 2006: MCWD submits requests for additional information and plan revisions. Chanhassen is a Community for Life - Providing for Today and Planning for Tomorrow Todd Gerhardt Minnehaha Creek Watershed District Surface Water Management Plan May 9, 2011 Page 2 • May 18, 2006: MCWD approves sixty -day extension request from City for review process. • July 12, 2006: Chanhassen submits requested information for approval. • July 20, 2006: MCWD approves the SWMP with the following conditions: • Execute a Memorandum of Understanding (MOU) with the MCWD; establishing implementation responsibilities as between the two bodies. • Incorporate prioritized list of capital improvements in the Chanhassen SWMP within 120 days. • Adoption of wetland ordinance the District determines to be at least as protective as the MCWD Rule D within 6 months of execution of the MOU. • July 5, 2007: MCWD approves their Comprehensive Water Resources Management Plan. • January 28, 2009: BWSR approves MCWD Comprehensive Water Resources Management Plan Amendment. • October 14, 2010: MCWD amended their 2007 Comprehensive Water Resources Management Plan incorporating their new Erosion and Wetland rules. • February 8, 2011: Met with Becky Houdek of MCWD to discus plan amendment and rule changes. • April 27, 2011: Met with Becky Houdek and Steve Christopher of MCWD to discuss plan amendment and rule changes. DISCUSSION After a review of our existing plan, the Minnehaha Creek Plan and state rules staff has compiled a list of amendments to the Chanhassen Second Generation Surface Water Management Plan (SWMP) that will be required. This will be a "broad brush" overview with additional details coming in future discussions. The City of Chanhassen falls within the jurisdictional boundaries of four water management organizations /watershed districts. All four of these agencies have been actively updating their local water management plan over the last year and only recently has the last of these agencies adopted their plan as shown in the following table. District Date of Adoption Minnehaha Creek Watershed District October 14, 2010 Carver County Water Management Organization October 26, 2010 Lower MN River Watershed District January 19, 2011 Riley Purgatory Bluff Creek Watershed District February 2, 2011 Table 1. Date of Plan Adoption for Local Water Plans Minnesota Statute 10313.235 requires that Chanhassen submit their plan to these agencies for review and comment and amend our plan to conform to the local water management plan. Most of the amendments that will be proposed to the plan will be required for all local water management plans regardless of the authoring agency. However, MCWD has incorporated rules into their plan. Carver County Water Management Organization (WENR) is currently going through the rule making g: \eng \terry\issue papers \050911 mcwd plan amendment issue paper I.docx Todd Gerhardt Minnehaha Creek Watershed District Surface Water Management Plan May 9, 2011 Page 3 process. While they have similar goals as the MCWD rules, it appears that they will be less restrictive. As a result, local controls that comply with MCWD rules will almost invariably be adequate to meet any WENR rules eventually adopted. Plan amendments can be grouped into 3 categories; general standards for local water management plans per MN Statutes 10313.235, requirements based upon Appendix C of the 2007 MCWD Local Water Management Plan, and local control changes based specifically upon MCWD rule revisions in the 2010 Local Water Management Plan but required under 10313.235. General Standards The general standards include those items that all agencies with local water management authority will require of Chanhassen. Many of these have already been incorporated and will simply need to be updated. Still others already exist in some other document or as a standalone document but need to be incorporated into the SWMP. Specifically, the City will need to: 1. Identify areas with known flooding issues as well as areas where our model predicts that public roads, private roads and private drives might overtop during infrequent rain events or where minimal freeboard exists. 2. Identify landlocked watersheds. 3. Include stormsewer infrastructure map. This map was not complete when the SWMP was adopted but has since been completed although it is still being updated. 4. Define water quality and water quantity protection methods adequate to meet standards established in the District's plan. This will be discussed further under Appendix C requirements. 5. Inclusion of National Pollution Discharge Elimination System (NPDES) requirements for Municipal Separate Storm Sewer System (MS4) cities including: 6. Identify areas of high erosion potential. 7. Metropolitan Land Planning Act (MLPA) Requirements. MCWD Appendix C Requirements Appendix C of the MCWD Local Water Management Plan is specific to waters within the district boundary. It identifies current loading and sets loading reduction goals. It also identifies other potential issues in surface waters and asks for specific management practices to address these issues. Chanhassen plan must include phosphorus load reductions to three surface water bodies. These waters and the reduction are included in Table 2 below. Receiving Water Annual Phosphorus Reduction Christmas Lake 7 lbs. Lake Minnewashta 27 lbs. South Lower Lake 3 lbs. Table 2. Annual Phosphorus Load Reduction Allocation g: \eng \terry\issue papers \050911 mcwd plan amendment issue paper l.doex Todd Gerhardt Minnehaha Creek Watershed District Surface Water Management Plan May 9, 2011 Page 4 The current SWMP and Capital Improvement Plan address Christmas Lake and Lake Minnewashta. However, when City staff and MCWD met during the authoring of the Chanhassen 2 nd Generation SWMP, South Lower Lake was not a subwatershed that was being considered. This has since changed and will need to be addressed in our plan amendment. Other issues identified in Appendix C include the monitoring the areas shown in Table 3. Monitoring Area Objective of Monitoring Efforts Lake Minnewashta Outlet Conveyance capacity and erosion Channel draining into Christmas Lake Scour, erosion and sediment deposition into Lake Lake St. Joe Establish baseline water quality and vegetation data; citizen involvement for education and outreach Table 3. Appendix C Monitoring Sites Under general standards a local water management plan must identify areas of high erosion potential. Chanhassen will need to review existing stormwater modeling data and determine where such areas exist and address these areas in our plan amendment. Code Amendments The City of Chanhassen is currently the local government authority with regulatory responsibility over wetlands, erosion control and stormwater management. Minnesota Statutes 103B.235 states that our plan must be amended to comply with the district plan(s). In this case that includes local controls as well. The City of Chanhassen does have the choice of allowing the District to enforce their rules within that portion of Chanhassen which lies within the District boundary. Staff feels that it is in the best interest of Chanhassen to maintain this authority rather than granting permitting authority of the District. Further, this is important to maintain continuity throughout the City of Chanhassen rather than having different rules in different parts of the City. To this end, staff will begin preparing code amendments to our existing wetland ordinance and erosion control ordinance for review and public hearing. Stormwater ordinance amendments will be needed within 180 days of the District's adopting their stormwater rule but will not be addressed at this time. Erosion Control Rule Changes to MCWD rules is not the sole impetus for amending our erosion control code. The 1972 Federal Clean Water Act (CWA) has led to the creation of the National Pollution Discharge Elimination System (NPDES). There are three permits under the NPDES, two of which apply directly to the City: the Municipal Separate Storm Sewer System (MS4) permit and.the General Construction Permit. Both of these permits have very specific requirements for sediment and erosion control best management practices; during construction and after final stabilization. A review of the new rule indicates that the changes to content within city code will be relatively minor. The changes will include what will trigger the need for preparing an erosion control plan and what items are required on that plan in order to ensure consistency between all agencies. Current city code is any land disturbing activity whereas the MCWD is 5,000 square feet of disturbance or 50 cubic yards of material. g: \eng \terry \issue papers \050911 mcwd plan amendment issue paper I.docx Todd Gerhardt Minnehaha Creek Watershed District Surface Water Management Plan May 9, 2011 Page 5 This amendment will also provide an opportunity to create a cleaner code regarding erosion and sediment control by consolidating our controls and regulations. Currently erosion and sediment control standards and practices can be found within Sections 7 -22, 7 -33, 18 -62, 19 -144 & 145, 20- 518 and 20 -1183 of the City Code. Wetland Protection Rule Chanhassen has had a wetland protection rule since before the 1991 MN Wetland Conservation Act. This rule has gone through several iterations over the past two decades; most recently when we adopted our Second Generation Surface Water Management Plan in August of 2006. The District maintains LGU status other places within the District. The new MCWD rule means three primary changes; what triggers buffers, required buffer widths, and excavation within type 1 and 2 wetlands. The following table illustrates the buffer requirements of each entity. Currently, staff is evaluating ways to meet the District buffer requirements while not increasing the encumbrance on privately owned land. It is important to note that these buffers would not apply to single family residences that make improvements to an existing structure. Under Minnesota Rules Chapter 8420 excavation within a Type 1 or 2- wetland is exempt from WCA rules unless the excavation results in the conversion of the basin to non - wetland. Under Chanhassen City Code, we exempt all activities exempted under Minnesota Rule. The new MCWD rule requires mitigation for excavation within Type 1 or 2 wetlands. Stormwater Management Rule As with erosion control, the 1972 Clean Water Act (CWA) is the driver behind most water quality rules. The CWA trickles down to local controls through the two National Pollution Discharge Elimination System (NPDES) permits mentioned earlier. As part of Chanhassen's Municipal Separate Storm Sewer System (MS4) permit, we were selected with 29 other cities to complete a pollutant loading assessment and Nondegradation Plan. These nondegradation cities were required g: \eng \terry\issue papers \050911 mcwd plan amendment issue paper I.docx MCWD WETLAND CHANHASSEN CITY CODE CH. 20; SEC. 20 -411 PROTECTION RULE: 6. BUFFER WIDTH *COMBINED PRINCIPAL *MIN *PRINCIPAL *ACCESSORY *PERMANENT STRUCTURE SETBACK % OF BUFFER *BASE APPLIED WETLAND STRUCTURE STRUCTURE BUFFER STRIP & BUFFER WIDTH REO. FOR BUFFER BUFFER CLASSIFICATION SETBACK SETBACK (MIN WIDTH) FROM DELINEATED NATIVE VEG. WIDTH WIDTH BNDRY OUTSTANDING 50 50 50 100 100 NIA N/A PRESERVE 40 20 40 80 100 75 67 MANAGE 1 30 15 25 55 100 40 34 MANAGE 2 30 15 20 50 OVER 50 30 24 MANAGE 3 30 15 16.5 46.5 OVER 50 20 16 Currently, staff is evaluating ways to meet the District buffer requirements while not increasing the encumbrance on privately owned land. It is important to note that these buffers would not apply to single family residences that make improvements to an existing structure. Under Minnesota Rules Chapter 8420 excavation within a Type 1 or 2- wetland is exempt from WCA rules unless the excavation results in the conversion of the basin to non - wetland. Under Chanhassen City Code, we exempt all activities exempted under Minnesota Rule. The new MCWD rule requires mitigation for excavation within Type 1 or 2 wetlands. Stormwater Management Rule As with erosion control, the 1972 Clean Water Act (CWA) is the driver behind most water quality rules. The CWA trickles down to local controls through the two National Pollution Discharge Elimination System (NPDES) permits mentioned earlier. As part of Chanhassen's Municipal Separate Storm Sewer System (MS4) permit, we were selected with 29 other cities to complete a pollutant loading assessment and Nondegradation Plan. These nondegradation cities were required g: \eng \terry\issue papers \050911 mcwd plan amendment issue paper I.docx Todd Gerhardt Minnehaha Creek Watershed District Surface Water Management Plan May 9, 2011 Page 6 to model pollutant loading for three parameters for 1988, 2010, and 2030. If they exceeded the 1988 level for any of the three parameters, they must amend their MS4 permit to include Best Management Practices (BMPs) aimed at returning to the 1988 loading levels. As with each of the 30 cities, Chanhassen exceeded total volume of runoff in every watershed. In addition to the soon -to -be adopted MCWD stormwater rule, the new NPDES MS4 permit is scheduled to be issued in January of 2012. It is anticipated that the nondegradation cities will need to amend their MS4 permits at this time to address loading. We will need to evaluate methods to minimize the amount of stormwater running off the land into our lakes and streams. This can be done through infiltration — percolating water through the soils into shallow, or deep, aquifers — or abstraction — capturing water at the source. MCWD's new rule is intended to address pollutant loading with an emphasis on capturing water on site rather than sending it downstream. Currently they are looking for the abstraction and/or infiltration of the first inch of rainfall unless it can be shown that is not possible, but in no case shall it be less than the first one -half inch. This is consistent with the NPDES General Construction permit requirements. We are seeing deficiencies within our own infrastructure that would be well served to reduce the amount of runoff from the landscape. So in addition to water quality benefits there will be a definite benefit to our existing and future infrastructure. Also involved with this rule are requirements for phosphorous reduction and reduced sediment loading. Except in very rare cases, these requirements will only apply to new impervious surfaces greater than 10,000 square feet. This rule will have the final public hearing on May 5 and will likely be adopted the last regular MCWD Board Meeting in May. By state law we will have one year to update our local controls to be compliant with theirs. We will begin a more detailed review of our local controls but staff feels that and amendments to our local controls be forestalled until we have a better understanding of what the new MS4 requirements will be. RECOMMENDATION Staff intends to bring the proposed plan amendments before the planning commission for review and public hearing and then to Council for further review and discussion. In order to meet the timeline set forth by MN State Statute, this will need to be completed by September 1 of this year. If there is specific information that Council wishes . to see, please let staff know so that we can be certain that information is made available to you. g: \eng \terry\issue papers \050911 mcwd plan amendment issue paper Ldocx