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Home My WebLink AboutItem 06Memorandum To: Mayor and City Council Allyn Kuennen, Interim City Administrator From: Monica Heil, Operations & Maintenance Engineer Mac Cafferty, Environmental Resources Manager John Hennen, Park Maintenance & Operations Manager Date: October 21, 2014 Subject: Antlers Park Retaining Wall Reconstruction City of Lakeville Parks & Recreation BACKGROUND Currently, there is a section of the existing modular block retaining wall along the shoreline of Antlers Park that is failing as noted in the attached photo. The failure creates a hazard for the park and beach users and causes shoreline erosion leading to sediment entering Lake Marion. Staff recently requested quotes from seven contractors to remove approximately 230 LF of existing modular block retaining wall, install approximately 105 LF of big block retaining wall and re -grade a portion of the existing area. The new wall will be relocated approximately 10 - 12 ft. back from the existing wall in the area of the failure. The big block retaining wall will withstand any consistent high water levels and wave action that occurs in this area. The contractor can begin construction yet this year, if so desired, and has until June 1, 2015 to complete the project. Also attached is a construction plan for the project which depicts the portion of the existing wall to be removed, installation of new big block wall and proposed grading limits on the site. PROJECT COST Four contractors submitted a quote for the project. The low quote for the project was submitted by Kevin Casey LLC at a cost of $41,882.75. FINANCING The project is proposed to be funded from the Environmental Resources Fund. The 2014 Environmental Resources Fund provided $50,000 of appropriations for wetland restoration including public property shoreline restoration projects. C:\Users\twallace\Desktop\Antlers Park Retaining Wall Reconstruction Memo 10-21-14JLH.docx RECOMMENDATION Staff is recommending the City Council direct staff to move forward with the execution of an Agreement with Kevin Casey LLC at a cost of $41,882.75 to make the repairs to the existing retaining wall. If the Mayor and City Council concur, the Agreement with Kevin Casey LLC would be placed on the November 3rd City Council Meeting agenda for approval. Attachments C:\Users\twallace\Desktop\Antlers Park Retaining Wall Reconstruction Memo 10-21-14 JLH.docx , PONl La PON 1) FIf 3 � 1 r � �. 'ala _�• � ,� � s �.. 2[I ]Q a 20 feat T Legend ® Proposed elevations (tAv=top of wall, bAv=bottom of wall) Existing ground elevation Tree t Existing top of wall 8t Existing bottom of wall ® Observed waterline (9/17/14) Existing wall to remain Proposed Big Block retaining wall (105 Ht) F Remove existing wall (2301f1) Ordinary High Water Level (983.1') if Proposed Grading outside OHW Impacts below OHW (650sgft) Cross -Sectional Detail (not to scale) Math Existing t/w 984.6'-964.7' _ Observed water line Mex 2% r slew --982.3' 10, ��w 982.4'-983.2' granular matenal� t,y8flas �I l` grading limits Remove tree Remove existing wail and grade to match existing with max slope of 1:10 pNotes: r shall be responsible ror phasing and construction of the new wall such that no temporary shall be required to construct the new wall. 2. Contractor shall provide a per linear foot estimate to construct the new releintrg Include:wall, to Include: a. MnDOT approved wet cast big block retaining wall block b. Wall ceps c. Any necessary reinforcement d. Any and all bedding materiel and/or pipe necessary to ensure adequate drainage e. Buried block, depth to be determined by the manufacture's engineer, knowing that the OHW of Lake Marion is 983.1 and the observed water elevation an 9117/14 was 992.3 f. Removal and proper disposal ofthe specified portions of the existing wall and • excess material between the old wall and the new wall. `r 3. The contractor shall Install the granular material between the water level and the new retaining well per the CrocsSection Detail. Grading work southeast and adjacent to the south retaining wall limits and restoration of the site (to be bid as grading - below OH" and shell include removal of existing unsuitable material and placement of new granular material per the Cross- Section Detail. 4. Grading outside the OHW shall include removal of excess material to construct a miximum 10:1 slope 9634 r1CT .iy&za+� A 9sa'4 . '. � • 3aa'S 389.5 r d. - • e992b7� 484Q5� i� � 9823 9e4�6 . 982 t AB.4 3 � 1 r � �. 'ala _�• � ,� � s �.. 2[I ]Q a 20 feat T Legend ® Proposed elevations (tAv=top of wall, bAv=bottom of wall) Existing ground elevation Tree t Existing top of wall 8t Existing bottom of wall ® Observed waterline (9/17/14) Existing wall to remain Proposed Big Block retaining wall (105 Ht) F Remove existing wall (2301f1) Ordinary High Water Level (983.1') if Proposed Grading outside OHW Impacts below OHW (650sgft) Cross -Sectional Detail (not to scale) Math Existing t/w 984.6'-964.7' _ Observed water line Mex 2% r slew --982.3' 10, ��w 982.4'-983.2' granular matenal� t,y8flas �I l` grading limits Remove tree Remove existing wail and grade to match existing with max slope of 1:10 pNotes: r shall be responsible ror phasing and construction of the new wall such that no temporary shall be required to construct the new wall. 2. Contractor shall provide a per linear foot estimate to construct the new releintrg Include:wall, to Include: a. MnDOT approved wet cast big block retaining wall block b. Wall ceps c. Any necessary reinforcement d. Any and all bedding materiel and/or pipe necessary to ensure adequate drainage e. Buried block, depth to be determined by the manufacture's engineer, knowing that the OHW of Lake Marion is 983.1 and the observed water elevation an 9117/14 was 992.3 f. Removal and proper disposal ofthe specified portions of the existing wall and • excess material between the old wall and the new wall. `r 3. The contractor shall Install the granular material between the water level and the new retaining well per the CrocsSection Detail. Grading work southeast and adjacent to the south retaining wall limits and restoration of the site (to be bid as grading - below OH" and shell include removal of existing unsuitable material and placement of new granular material per the Cross- Section Detail. 4. Grading outside the OHW shall include removal of excess material to construct a miximum 10:1 slope