The URL can be used to link to this page

Home My WebLink About#03 - Stormwater Management MOU STAFF REPORT DATE: September 5, 2023 CONSENT AGENDA ITEM: Approve Stormwater Management Memorandum of Understanding with Valley Branch Watershed District, City of Lake Elmo and Washington County SUBMITTED BY: Jack Griffin, City Engineer REVIEWED BY: Krintina Handt, City Administrator Sarah Sonsalla, City Attorney Marty Powers, Public Works Director Chad Isakson, Assistant City Engineer ISSUE BEFORE COUNCIL: Should the City Council approve the Stormwater Management Memorandum of Understanding (MOU) with the Valley Branch Watershed District (VBWD), City of Lake Elmo and Washington County? BACKGROUND: In December, 2022 the City of Lake Elmo approved the Preliminary Plat/Plans for the Schiltgen Farms subdivision (now known as Northstar). In connection with this development, the developer is required to construct stormwater management detention ponds and implement a stormwater reuse irrigation system consistent with the approved Stormwater Management Plan dated February 15, 2023. Because the subdivision layout would not have reserved land that could be used in the future for the construction of stormwater management basins, the City Engineer required the development’s stormwater management systems to be oversized with the intention that this excess capacity would be reserved to address the stormwater management mitigation for the future County roadway improvements along Stillwater Boulevard (CSAH 14) and Lake Elmo Avenue (CSAH 17). Therefore, the Schiltgen Farms stormwater detention ponds and stormwater reuse irrigation system will be sized to provide the additional rate and volume control necessary to mitigate the future County Roadway improvements, including 8.5 acres of total impervious surface and 5.4 acres of new impervious surfaces with the runoff being directed to the proposed Schitgen Farms (Northstar) stormwater basins. PROPOSAL DETAILS/ANALYSIS: In order to document and memorialize the requirements, procedures, and processes for permitting the future County roadway improvements and to allow for the use and credit of the in-place excess stormwater management capacity provided by the Schiltgen Farms (Norhtstar) subdivision, the VBWD, City of Lake Elmo and Washington County staff have prepared a Memorandum of Understanding (MOU). The MOU outlines the following provisions and requirements: 1. Stormwater management capacity will be provided for up to 8.5 acres of total impervious surface and 5.4 acres of new impervious surfaces for the future County roadway improvements, if the stormwater runoff from the above surfaces are captured and discharged to the Schiltgen Farms (Northstar) subdivision stormwater reuse irrigation source ponds. 2. When evaluating the actual County roadway improvement plans, the peak discharge rates for the reconstructed roadways and intersection shall be compared to the “existing” and “proposed” peak discharge rate in Table 5.6 of the AE2S February 15, 2023 Stormwater Management Plan for the Schiltgen Farms Development (attached below). FISCAL IMPACT: Through the adoption of the Stormwater Management MOU, the future County Roadway improvements along Stillwater Boulevard (CSAH 14) and Lake Elmo Avenue (CSAH 17) will be able to be constructed without constructing additional stormwater management facilities. This will result in a significant cost savings to the City of Lake Elmo as the City will not be required to participate in the shared costs associated with land acquisition and construction of the County stormwater management facilities. RECOMMENDATION: Staff is recommending that the City Council adopt, as part of the consent agenda, a resolution approving the Memorandum of Understanding with the Valley Branch Watershed District, City of Lake Elmo and Washington County as outlined in the attached MOU. If removed from the consent agenda, the recommended motion for this action is as follows: “Move to approve Resolution No. 2023-082, approving a Stormwater Management Memorandum of Understanding with the Valley Branch Watershed District, City of Lake Elmo and Washington County to address permitting of the future County roadway improvements along Stillwater Boulevard (CSAH14) and Lake Elmo Avenue (CSAH17).” ATTACHMENTS: 1. Resolution Approving the Stormwater Management MOU with VBWD, City of Lake Elmo and Washington County. 2. Memorandum of Understanding (MOU). 3. Figure 20. Future County Road Expansion Impervious Surfaces. CITY OF LAKE ELMO WASHINGTON COUNTY STATE OF MINNESOTA RESOLUTION NO. 2023-082 A RESOLUTION APPROVING A STORMWATER MANAGEMENT MEMORANDUM OF UNDERSTANDING WITH THE VALLEY BRANCH WATERSHED DISTRICT, CITY OF LAKE ELMO AND WASHINGTON COUNTY WHEREAS, in association with the Northstar subdivision (also known as the Schilten Farms development), the developer will be required to construct stormwater management detention ponds and implement a stormwater reuse irrigation system consistent with the approved Stormwater Management Plan dated February 15, 2023; and WHEREAS, in addition to oversizing the stormwater management detention ponds to provide for the Village Area Phase 2 Regional Stormwater Pond, the stormwater management systems will include excess capacity that is intended to be reserved to address the stormwater management mitigation for the future County roadway improvements along Stillwater Boulevard (CSAH 14) and Lake Elmo Avenue (CSAH 17); and WHEREAS, a Memorandum of Understanding (MOU) between the Valley Branch Watershed District, the City of Lake Elmo, and Washington County was prepared to establish the requirements, procedures, and processes for permitting the future County roadway improvements along Stillwater Boulevard (CSAH 14) and Lake Elmo Avenue (CSAH 17) to allow for the use and credit of the in-place excess capacity provided by the Northstar (Schiltgen Farms) subdivision stormwater management systems. NOW, THEREFORE, IT IS HEREBY RESOLVED, 1. The Memorandum of Understanding between the Valley Branch Watershed District, City of Lake Elmo and Washington County to regulate the use of the excess stormwater rate and volume control capacity of the Northstar (Schiltgen Farms) Stormwater Management system is approved. 2. The Mayor and City Administrator are hereby directed to execute the Memorandum of Understanding with the Valley Branch Watershed District and Washington County. ADOPTED BY THE LAKE ELMO CITY COUNCIL ON THE FIFTH DAY OF SEPTEMBER, 2023. CITY OF LAKE ELMO By: __________________________ Charles Cadenhead (Seal) Mayor ATTEST: ________________________________ Julie Johnson City Clerk 1 MEMORANDUM OF UNDERSTANDING Between the VALLEY BRANCH WATERSHED DISTRICT And the CITY OF LAKE ELMO And WASHINGTON COUNTY For the PRESERVATION, PROTECTION, AND ENHANCEMENT OF WATER RESOURCES THROUGH STORMWATER RUNOFF MANAGEMENT AT THE CSAH 14‐CSAH 17 INTERSECTION ARTICLE I INTRODUCTION, BACKGROUND, AND PURPOSE 1.1 This Memorandum of Understanding (MOU) documents activities and decisions of the Valley Branch Watershed District (VBWD), the City of Lake Elmo (Lake Elmo), and Washington County (County) regarding stormwater management at the western County State Aid Highway (CSAH) 14 (Stillwater Boulevard) and CSAH 17 (Lake Elmo Avenue) intersection (Intersection) in the City of Lake Elmo. Through the procedures and processes set forth in this document, all parties wish that due consideration be given to water and related land resources under the jurisdiction of all parties. 1.2 In association with the Northstar subdivision (also known as Schiltgen South, and also known as Schiltgen Farms development), the developer made assumptions for reconstruction of the Intersection. One assumption included additional 5.4 acres of new impervious surfaces. The Schiltgen South designers included stormwater management of this new impervious surface area of the Intersection in the Schiltgen South development, including an assumed future roadway expansion with a total impervious surface area of 8.5 acres and 5.4 acres of new impervious surface area, consistent with Figure 20 attached hereto. Stormwater management included controlling the peak discharge rates for the 2‐, 10‐, and 100‐year 24‐hour design storms and the 10‐day 100‐ year snowmelt event. It also included capturing 1.1 inches times the 5.4 acres of new impervious surface and using the captured runoff for irrigation on the Schiltgen South development. 1.2.1 It is acknowledged that the intent of Figure 20 is to account for area in the vicinity of the intersection of CSAH 14 and CSAH 17 that could be routed to the Schiltgen South ponds. It is understood by the signing parties that this figure was developed in GIS and may not precisely identify exact watershed limits, especially beyond where topographic survey data is available. Rather, it is understood that minor differences in watershed areas or existing pavement areas, if and when more precise data is available, does not nullify the agreements documented in this MOU. 1.3 The VBWD approved Permit 2023‐01 on January 26, 2023, for the Schiltgen South development. 2 1.4 Lake Elmo approved Preliminary Plans dated 03/30/2023, and Stormwater Management Report dated 02/15/2023, for the Schiltgen South Development. 1.5 The County reviewed the roadway plans dated 01/22/2023 and the Stormwater Management Report dated 02/15/2023 for the Schiltgen Farms development. At the time of construction and permitting, if the Stormwater Management Report has changed, the City, VBWD, and the County agree to reconvene and amend this MOU as necessary. 1.6 All parties recognize that the objectives of this MOU can best be realized through close coordination and cooperation. ARTICLE II ONGOING PERMITTING OF INTERSECTION RECONSTRUCTION ACTIVITIES 2.1 Future reconstruction of the Intersection is expected. When reconstruction of the Intersection is planned, all parties shall meet to review stormwater management requirements. 2.2 Reconstructed Intersection activities shall conform to all regulations at the time of the reconstruction. 2.3 The peak discharge rates for the reconstructed Intersection shall be compared to the “existing” and “proposed” peak discharge rate in Table 5.6 of the AE2S January 9 and February 15, 2023, Stormwater Management Plan for the Schiltgen Farms Development, copied below. The listed peak discharge rates are for the outlet of the 36‐inch diameter corrugated metal pipe outlet south of CSAH 14, at the northeast corner of parcel 1302921230071. 2.4 The predicted peak discharge rates of the reconstructed Intersection must not exceed the peak discharge rates of the “proposed” condition listed in paragraph 2.3. 2.5 The VBWD will require no additional stormwater volume control measures for the reconstructed Intersection if: 1) the net increase of impervious surfaces of the reconstructed Intersection are 5.4 acres or less, and 2) a total of 8.5 acres of impervious surface from the reconstructed Intersection drains to the stormwater ponds on the Schiltgen South development that are used as reservoirs for the irrigation system. 3 If the criteria outlined in Section 2.5(1) and (2) are not met, VBWD will require additional stormwater volume control measures for the reconstructed Intersection. 2.6 The undersigning parties agree to work with one another to share functional copies of data necessary for further analysis, if needed. This could include but is not limited to copies of survey data, stormwater models, or development plans and as‐built drawings. 2.7 The undersigned parties agree that if the Schiltgen South stormwater management of the new impervious surface area of the Intersection in the Schiltgen South development does not function as intended, the City, VBWD, and the County agree to reconvene and amend this MOU as necessary. 2.7 This Memorandum of Understanding is intended to outline the agreement of the parties as it relates to preserving water resources in conjunction with the reconstruction of the Intersection, and not as a waiver of any other rules or enforcement mechanisms available to the parties. This Memorandum of Understanding shall be effective immediately upon signature of Lake Elmo, VBWD, and the County and shall remain in effect until decided otherwise by any signing party. 4 CITY OF LAKE ELMO By______________________________________ Date: _________________________ Its Mayor By______________________________________ Date: _________________________ Its City Clerk APPROVED AS TO FORM: _________________________________________ Date: _________________________ City Attorney, City of Lake Elmo WASHINGTON COUNTY By______________________________________ Date: _________________________ Its Board Chair By______________________________________ Date: _________________________ Its County Administrator APPROVED AS TO FORM: _________________________________________ Date: _________________________ County Attorney, Washington County VALLEY BRANCH WATERSHED DISTRICT By____________________________________ Date:________________________ Its President APPROVED AS TO FORM: _________________________________________ Date: _________________________ District Attorney, Valley Branch Watershed District