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Agenda and Packet CHANHASSEN PARK AND RECREATION COMMISSION REGULAR MEETING SUMMARY MINUTES JULY 24, 2018 Chairman Scharfenberg called the meeting to order at 7:30 pm. MEMBERS PRESENT: Karl Tsuchiya, Cole Kelly, Jim Boettcher, Meredith Petouvis, Rick Echternacht, Grant Schaeferle and Steve Scharfenberg. MEMBERS ABSENT: Joseph Scanlon STAFF PRESENT: Todd Hoffman, Park ad Rec Director; and Katie Mathews, Recreation Supervisor APPROVAL OF AGENDA: the agenda was approved as presented PUBLIC ANNOUNCEMENTS; Park and Recreation Director Hoffman informed the commission about Night Out on the Town, Thursday, July 26 downtown Chanhassen and National Night Out, Tuesday, August 7 VISITOR PRESENTATIONS: Dennis Gallaher, Southwest Metro Pickelball Club APPROVAL OF MINUETS: Boettcher moved, Echternacht seconded to approve the verbatim and summary minuets of the Park and Recreation Commission meeting dated June 26, 2018. All voted in favor and the motion carried unanimously with a vote of 7 to 0. NEW BUSINESS Initiate discussion regarding recommendation to City Council, 2019 through 2023 park and trail acquisition and development capital improvement program (CIP): Todd Hoffman gave an overview of the scheduled 2019 Park and Trail Capital Improvement Program (CIP) th REPORTS: Katie Mathews gave a report on the 2018 4 of July Celebration COMISSION MEMBER COMMITTEE REPORTS None COMMISSION MEMBER PRESENTATIONS None AMINISTRATIVE PACKET ADJOURNMENT Boettcher moved, Echternacht seconded to adjourn the meeting. All voted in favor and the motion carried. The Park and Recreation Commission meeting was adjourned. Prepared and submitted by Todd Hoffman Park and Recreation Director ^Ak I WENCK Responsive partner. Exceptional outcomes. July 17, 2018 Dennis Wasley Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, MN 55155 RE: Alum Treatments on Lotus and Rice Marsh Lakes Dear Mr. Wasley: We are working with the Riley Purgatory Bluff Creek Watershed District (RPBCWD) to conduct aluminum sulfate (alum) treatments on Lotus Lake (10-0006-00) and Rice Marsh Lake (10- 0001-00). Lotus Lake is a deep, 248-acre lake, located at the headwaters of Purgatory Creek in Chanhassen (Figure 1). Rice Marsh Lake is a shallow, 83-acre lake in the Riley Creek chain of lakes and is located on the border of Chanhassen and Eden Prairie (Figure 2). This project involves initial applications of liquid alum to Lotus and Rice Marsh Lakes to control internal phosphorus loading and improve water quality. For both lakes, the first application is a portion of the calculated dose necessary to adequately reduce internal phosphorus loading. A follow-up dose may be applied at a later date after additional monitoring has occurred. Lotus and Rice Marsh Lakes are both eutrophic. Lotus Lake has been listed as impaired for excess nutrients by the MPCA since 2007. Rice Marsh Lake has not been formally assessed for impairment status, but its total phosphorus concentrations are well above shallow lake standards in most years. In both lakes, internal phosphorus loading has been identified as a major source of phosphorus loading during the summer growing season. The most recent Use Attainability Assessments (UAAs) for each fake estimated that internal phosphorus loading accounts for 680/c (732 lbs./yr.) of Lotus Lake's total annual phosphorus budget (Barr 2017) and 3411/o (539 lbs./yr.) of Rice Marsh Lake's total annual phosphorus budget (Barr 2016). Consequently, the UAA implementation plans for both lakes state that in -lake sediment treatments (i.e., alum treatments) are necessary, in combination with watershed practices, for the lakes to meet state water quality standards. A number of studies were completed to evaluate phosphorus contributions to Lotus and Rice Marsh Lakes and their potential remediation including: • Lotus Lake Alum Dosing. Wenck 2018. The memo uses sediment chemistry and phosphorus release rates to calculate alum dosing cost estimates. The memo also determines the maximum allowable dose for Lotus Lake to ensure that aquatic life is protected. • Rice Marsh Lake Alum Dosing. Wenck 2017. The memo uses sediment chemistry and phosphorus release rates to calculate alum dosing cost estimates. The memo also determines the maximum allowable dose for Rice Marsh Lake to ensure that aquatic life is protected. Updated Rice Marsh Lake Alum Dosing. Wenck 2018. The memo updated the original dose prescribed for Rice Marsh Lake using a literature review, dosing considerations for biogenic P, and dosing for P release. Wenck Associates, Inc. 1 7500 Olson Memorial Highway I Golden Valley, MN 55427 Toll Free 800-472-2232 Main 763-252-6800 Email wenckmp@wenck.com web wenck.com Dennis Wasley Minnesota Pollution Control Agency 7/17/18 V^V WEiNCK Responsive partner. Exceptional outcomes. • Lotus, Silver, Duck, Round, Mitchell, Red Rock Use Attainability Analysis Update; Lake Idlewild and Staring Lake Use Attainability Analysis; and Lower Purgatory Creek Stabilization Study. Barr 2016. The report provides an updated nutrient budget and source assessment for Lotus Lake. The study indicates that internal load control is necessary to reduce in -lake phosphorus concentrations to state's deep lake standard. • Rice Marsh Lake and Lake Riley: Use Attainability Analysis Update. Barr 2016. The report provides an updated nutrient budget and source assessment for Rice Marsh Lake. The study indicates that internal load control is necessary to reduce in -lake phosphorus concentrations to the state's deep lake standard. • Internal Phosphorus Loading and Alum Dosage Considerations for Lotus Lake, Minnesota. University of Wisconsin Stout 2018. The study reports sediment P release and sediment chemistry in Lotus Lake. • Internal Phosphorus Loading and Alum Dosage Considerations for Rice Marsh Lake, Minnesota. University of Wisconsin Stout 2017. The study reports sediment P release and sediment chemistry in Rice Marsh Lake. • Aquatic Plant Community of Lake Ann, Lotus, Lucy, Mitchell, Susan, Riley, and Staring within the Riley Purgatory Bluff Creek Watershed: Final Report 2009-2914, Jaka, JD 2014. Alum will be applied to selective areas of each lake. For Lotus Lake, alum will be applied to two zones located in the southern and eastern areas of the lake (Figure 3). Zone 1, which is in the eastern portion of the lake, is approximately 44 acres and zone 2, which is in the southern portion of the lake, is approximately 40 acres. Treatment zones and alum doses for each zone were determined through an internal phosphorus release study and an alum dosing study in which RPBCWD partnered with Wenck and the University of Wisconsin Stout (UW-Stout). For these studies, sediment cores were collected from Lotus Lake in 2017 and were analyzed at UW-Stout to determine the amount of sediment phosphorus release from lake sediments. Results indicated that Lotus Lake's anaerobic internal phosphorus release rate averaged about 11.3 mg/m2/day in the deep parts of the lake. Wenck used this release rate and other sediment data to determine that Zone 1 should receive an alum dose of 1,276 gal/ac or 55,881 gallons total and zone 2 should receive an alum dose of 4,055 gal/ac or 160,229 gallons total. These doses will inactivate 90% of the redox- phosphorus in the upper 4 centimeters of zone 1's sediment and the upper 7 centimeters of zone 2's sediment. The total dose of alum to be applied to Lotus Lake is 216,110 gallons. This application in Fall of 2018 is half of the total determined dose and includes the application of 108,055 gallons of alum, or an application rate of 638 gal/ac in zone 1 and 2,028 gal/ac in zone 2 (Figure 3). For Rice Marsh Lake, alum will be applied to the area of the lake that is 4 feet or deeper, an area of approximately 36 acres (Figure 4). As for Lotus Lake, this treatment zone and the prescribed alum dose were determined through an internal phosphorus release study and an alum dosing study in which RPBCWD partnered with Wenck and the UW-Stout. For these studies, sediment cores were collected from Rice Marsh Lake in 2016 and were analyzed at UW- Stout to determine the amount of sediment phosphorus release from lake sediments. Results indicated that Rice Marsh Lake's anaerobic internal phosphorus release rate was about 6.3 mg/m2/day. Wenck used this release rate and other sediment data to determine that the treatment area should receive an initial alum dose of 913 gal/ac or 33,058 gallons total (Figure 9 V:\Technical\3057 RPBCWQ\0010 Rice Marsh and Lotus Plans.Specs\MPCA Lete\Rice Marsh and Lotus Lakes Alum Proposal Letter.docx Dennis Wasley Minnesota Pollution Control Agency 7/17/18 e^o WEICK Responsive partner. Exceptional outcomes. 4). The initial dose of alum prescribed for Rice Marsh Lake for application in Fall of 2018 is 33,058 gallons. Future alum doses will likely be necessary in Rice Marsh Lake since most of the sediment phosphorus is stored as labile phosphorus, a fraction of phosphorus that releases from sediment much slower redox phosphorus, which comprises most of the phosphorus in Lotus Lake sediment. Based on our experience, Rice Marsh Lake may need as much as 3 to 4 times this initial dose of alum to convert 90% of the labile P to aluminum bound P. However, we selected an adaptive approach of periodic alum doses with routine monitoring so the minimum effective alum dose will be used to achieve District goals. For both Lotus and Rice Marsh Lake, UW-Stout also determined the maximum allowable dose to prevent aquatic toxicity based on alum titration jar tests. The maximum allowable dose was determined to be 15 mg AI/L for Lotus Lake and 20 mg Al/L for Rice Marsh Lake. The prescribed Fall 2018 alum doses for Lotus and Rice Marsh Lakes would result in lake aluminum concentrations of 8 mg AI/L and 16 mg/L, respectively, which are both well below maximum allowable doses. RPBCWD staff will collect alkalinity and pH in the week prior to application to validate the buffering capacity of the lake. RPBCWD staff will also be on site measuring pH, alkalinity, dissolved aluminum, and sulfate throughout the water column during the entire application process. Additionally, RPBCWD staff will look for visual signs of potential impacts to fish during the application. If the pH does drop below 6.0 application will be stopped immediately. If the application is stopped, RPBCWD staff will continue to monitor the pH to determine if it is possible to continue the application or if an alternate plan needs to be developed to proceed with the project. The project will be placed out for bid by RPBCWD on or near August 13, 2018. We have tentatively scheduled the first application treatment for September/October of 2018. The alum application is anticipated to be completed over the course of 15 days. The RPBCWD recognizes the need to reduce watershed nutrient inputs to Lotus and Rice Marsh Lakes, not only to ensure achievement of state water quality standards, but also to ensure long-term effectiveness of the alum treatment. The RPBCWD, along with local partners, will continue to identify and implement watershed nutrient reduction projects in the future. We are requesting that the MPCA review the information presented in this document and provide a letter for authorization at your earliest convenience to allow us to maintain our schedule. We are also aware that the local DNR fisheries office must be notified of a project of this nature and we will be contacting Daryll Ellison in the West Metro Fisheries office to inform him of the application and the project. The DNR has also been copied on this letter. Should you have any questions, or need clarification of anything presented in this letter, please do not hesitate to call me at 763-252-6829. Sincerely, Wenck Associates, Inc. Riley Purgatory Bluff Creek WD Joe Bischoff Claire Bleser Principal, Aquatic Ecologist Administrator 3 V:\Technical\3057 RPBCI.JD\0010 %ce Narsh and Lotus Plans. Specs\vPCA Letter\P.ice Marsh and Lotus Lakes Alum Proposal Letter.docx Dennis Wasley Minnesota Pollution Control WENCK Agency 7/17/18 Responsive partner. Exceptional outcomes. C: Daryl Ellison, DNR West Metro Area Fisheries Supervisor Kate Drewry, DNR Hydrologist Jennie Skancke, DNR Hydrologist Vanessa Strong, City of Chanhassen Todd Hoffman, City of Chanhassen Leslie Stovring, City of Eden Prairie Dave Modrow, City of Eden Prairie Matt Bourne, City of Eden Prairie Chris Zadak, Minnesota Pollution Control Agency enc: • Figure 1. Lotus Lake Location. • Figure 2. Rice Marsh Lake Location. • Figure 3. Alum treatment zones for Lotus Lake. • Figure 4. 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