08/08/2007 P&Z Packet - Laserfiche WebLink

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TKDA . ENGINEERS • ARCHITEU I S - PLANNERS • MEMORANDUM To: Thomas D. Prew, P.E. Reference: Moon Marsh 444 Cedar Street. Suite 1500 Saint Paul, MN 55101 -2140 (651) 292 -4400 (651) 292-0083 Fax www.tkda.com Copies To: James E. Studenski, P.E. Drainage Review City of Lino Lakes, Minnesota From: Connie J. Taillon, P.E. Proj. No.: 13810.002 Date: August 3, 2007 Routing: The following drainage review is based on these submittals: 1. Comment response letter submitted by Hult & Associates, Inc., undated. 2. Moon Marsh Preliminary Grading, Drainage, and Erosion Control Plans, and Storm Water Pollution Prevention Plan submitted by Hult & Associates, Inc., dated October 4, 2006, and revised July 24, 2007. 3. Moon Marsh Drainage Report submitted by Hult & Associates, Inc., dated July 25 2007. New comments are in bold and identify items that need to be addressed. The following are minor plan, calculations, and drafting corrections that must be addressed prior to final approval: 1. Submit a geotechnical report summarizing the seasonal high water mark which is identified as the mottled soils or highest anticipated water table. The lowest floor elevation is required to be 4 feet above the seasonal high water mark. It appears from the percolation report that mottled soils have been encountered in the test area between 12" to 20" below the ground surface. 06/19/07 The Geotechnical Report indicates that groundwater was found in the vicinity of 886± to 888.5 ±. The report goes on to state that `it is unlikely that this investigation has found groundwater at its highest level. Most likely, maximum groundwater on the site is equivalent to the ordinary high water level (not short term flood level) of the vicinity wetland'. A seasonal high water mark has not been identified in the report and will need to be submitted. Based on the groundwater levels determined in the Geotechnical Report, Lots 1 and 2, Block 1, does not meet the City's minimum low floor requirement as stated in comment 1 above. 08/03/07 As per discussions with the City, the low floor elevation has been raised to 892.5 for Lots 1 -2, Block 1, and Lot 1, Block 3. This item has been addressed. 2. The filtration areas may not be feasible due to the presence of mottled soils near the surface which indicates high ground water levels. Groundwater could affect the efficiency of these systems. 08/03/07 This item has been addressed. 3. Identify the location and elevation of the outlet and emergency overflow for all wetlands. Low openings are required to be a minimum of 1 foot above the emergency overflow elevation.