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5. Modify Highcrest Meadows Storm Water Pond Design, Grading & Landscaping in the Area CITY OF CHANHASSEN 7700 Market Boulevard PO Box 147 Chanhassen, MN 55317 Administration Phone 952.2271100 Fax 952.227 1110 Building Inspections Phone 952.2271180 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: 952.2271120 Fax 952.2271110 Recreation Center 2310 Coulter Boulevard Phone: 952.227 1400 Fax 952.2271404 Planning & Natural Resources Phone 952.227 1130 Fax 952.227 1110 Public Works 1591 Park Road Phone 952.2271300 Fax 952.2271310 Senior Center Phone 952.2271125 Fax 952.227 1110 Web Site www.ci.chanhassen.mn.us ~ - MEMORANDUM TO: Paul Oehme, CIty Engineer/PublIc Works DIrector QD Alyson Fauske, AssIstant CIty EngIneer (Xt FROM: DATE: August 14,2006 SUBJ: Longacres Homeowners/Developers Proposed changes to the Highcrest Meadows Stormwater Pond DesIgn, Grading and LandscapIng In the Area - Project No. 05-07-1 BACKGROUND For several months, City Staff has been workIng wIth the Longacres resIdents to finalIze addItIOnal work with the Highcrest Meadows project that was requested by some Longacres resIdents. The developer has agreed to make some addItIOnal Improvements to hIS development. The developer's contractor IS on site completIng punch lIst Items, therefore, staff requests direction from CIty CouncIl regarding the Longacres resIdents' requests. Staff has made recommendatIOns for each of the homeowner's requests. ThIS work, again, is in addition to the requirements set forth In the development contract and none of the work IS reqUIred In the Development Contract. Request #1: Place fill at the bottom of the retaining wall to minimize wall height. Longacres request: Developer should place fill at bottom of wall to reduce exposure of wall to 12'. Wall draintIlIng ports should be extended to allow consistent elevation of fill material. Jerry Frederick's notes per phone conversation July 26 with Paul Oehme: Will reVIew Anchor Wall plan detaIls with developer, see Detail 4/W7, Page 7 of approved plans. Jerry provided contact, John Hique at Anchor City, to proVIde elevatIOn-drawing showing estImated fill and settlIng, before begInnIng proJect. Paul Oehme's response: I have reviewed the plans and discussed the Issue with our building officials, the City Manager and the developer. It was our understandIng that thIS request was modified with the construction of a swale, per your conversation WIth the City Manager. The developer is wIllIng to make the changes as requested in this paragraph; however, he is NOT willIng The City of Chanhassen · A growing community with clean lakes, quality schools, a charming downtown, thriving businesses, winding trails, and beautiful parks. A great place to live, work, and play Paul Oehme Highcrest Meadows Stormwater Pond August 14, 2006 Page 2 to make the other improvements you have requested as described in this file (#'s 2, 3, 4) if request # 1 is accepted. '. View of retaining wall. Fill has been placed at the bottom of the wall. Arrow points to wall drain, where no fill has been placed. Stafrs Recommendation: The developer shall place up to three feet (3 ') of fill at the bottom of the retaining wall as soon as possible. No fill shall be placed at the wall drain locations. Extending the wall draintile out may interfere with future maintenance/cleaning operations of the pond. Request #2: Do not add to the height of the retaining wall (as suggested by the developer's engineer in order to grade a swale and reduce the run off area to the west of the wall). Longacres response: The developer was in and completed the aluminum fence prior to the June 22 letter, so we would agree they probably will not increase wall height. Note: The second sentence in the response is incorrect: The statement "Therefore the area draining into the Dettmer parcel cannot be reduced." Note the following correction: We believe that the City did not provide written support as we requested in the April 26 petition stating why the change in retaining wall height would change any drainage issues. Adding more height to the wall was only one solution the city attempted to provide. It does not mean that the Dettmer's runoff cannot be reduced. We await an optional solution. Jerry Frederick's notes per phone conversation July 26 with Paul Oehme: City to provide detail of proposed swale at west end of wall. Paul Oehme Highcrest Meadows Stormwater Pond August 14, 2006 Page 3 Paul Oehme's response: Alyson is drafting a plan detailing the proposed swale. Stafrs Recommendation: No additional retaining wall block shall be placed at this location. City staff shall provide a grading plan for the swale on the west side of the wall so that the developer's contractor can complete the grading. Request #3: Longacres residents to approve the location of the tree plantings at the bottom of the tree Longacres response: Please add: Planting of 9' coniferous (pine) trees as measured from base of tree to top of tree (not including ball and burlap) located on southern side of maintenance right-of-way. Jerry Frederick's notes per phone conversation July 26 with Paul Oehme: Jerry to get count of Compact Mugo Pine plants and forward to Paul. Paul will talk to developer and see if agreeable to planting Compact Mugo Pine for planting at wall, tree heights to be called out in new response. Trees planted near common lot line to allow right-of-way access to pond. Compact Mugo Pine or equivalent planted every 7' at base of wall. Climbing vines at top and bottom of wall agreed previously by developer. Paul to confirm climbing vines are still agreed upon by developer. Longacres will contact Jill Sinclair with the Longacres person of authority for placement when ready. Paul Oehme's response: The developer is willing to plant the vines. The developer is only willing to plant 12 trees. Stafrs Recommendation: The developer shall plant up to twelve (12) trees at the bottom of the retaining wall. The tree planting locations shall be staked by the City Forester, the developer and/or the developer's contractor. One (1) representative from the Longacres neighborhood may accompany the City Forester, the developer and/or the developer's contractor. If the neighborhood representative is unable to attend the on-site meeting, the neighborhood representative may review the staked locations and notify the City Forester if the locations are acceptable, or propose changes. Paul Oehme Highcrest Meadows Stormwater Pond August 14, 2006 Page 4 Request #4: Redirect the pond outlet so that it does not outlet directly to the south, towards the Frederick property. Longacres response: Please add: "Reconnect and redirect 18" pipe." Jerry Frederick's notes per phone conversation July 26 with Paul Oehme: "Re-Iay the pipe" was defined by Paul as the outtake that extends from the catch basin into the drainage easement. That pipe alone will be re-Iayed and additional rip rap placed The ditch will also be cleaned. In addition, riprap area west of outlet structure and remove high spot in area next to out port. Paul Oehme's response: Agreed. Outlet pipe was constructed per plan. The developer has agreed to re-Iay the pipe as requested by the homeowners. Stafrs Recommendation: The developer's contractor may re-Iay the pond outlet pipe. The pond hydraulics should not be affected by this work. Request #5: Residents request an official letter from City of Chanhassen confirming both LA and HCM drainage systems meet current code and are designed to operate as one complete system. The letter based on an independent assessment providing positive data via experienced-based metrics demonstrating long-term survivability. Supporting data to include all existing Highcrest walls, property, associated holding ponds, drainage pipes, systems currently installed are in fact installed to plan, to specification, to city code and in compliance with adjoining Longacres properties, elevations, wetlands and city drainage systems by September 1, 2006. Developer of High crest Meadows performance bond release tied to demonstration ofperformance and survivability of systems. Paul Oehme Highcrest Meadows Stormwater Pond August 14, 2006 Page 5 Jerry Frederick's notes per phone conversation July 26 with Paul Oehme: City to provide document with as-built data confirming systems compatibility. Current document provided was unauthored. Paul Oehme's response: The City does not have the as-built drawings from the developer at this time. Homeowners may obtain a copy after the City has accepted them. Stafrs Recommendation: None required. Request #6: A plan for clean up of existing Longacres wetlands and holding ponds from storm runoff caused by the Highcrest development during September and October, 2005, and spring of 2006 is promulgated and enforced by the City of Chanhassen; including start dates, method of clean up, completion and process for verification of clean up by September 1, 2006. Provided in July 18 response. Paul Oehme's response: The cleanup is part of the developer's responsibility. This work will be addressed at the same time the other items are completed. Stafrs Recommendation: None required. Longacres residents: We look forward to your written response. Please make certain that the developer maintains the cease and desist criteria until we are in agreement on the items listed above until all parties involved can reach an agreement. Stafrs Recommendation: The developer should be authorized to complete these items as soon as possible. The approved meeting minutes from this Council Meeting shall satisfy the requirements for a written response.