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INFORMATION #2 04-16-2001Information MEMORANDUM TO: FROM: DATE: SUBJECT: Mayor and City Council ~A. Scott Harlickar, Senior Planner~,~-~ April 16, :ZOO I Information Memo on Halpau~ Propers/ In response to Ron and Yvonne Halpaus's complaint regarding stormwater runoff ponding on their property, on Tuesday April I 0th city staff met with the developer of Seven Oaks on site to review the situation. While walking along the property line, is was apparent that some puddling of water did occur on the Halpaus property as well as on the developer's property. The puddling occurs in a natural depression located on the Halpaus property and on the developer's property. The pre-development conditions, as shown on the attached contour map, indicate that water has collected in this depression prior to grading as there is no natural outlet until the water is about 4 feet deep. There was about 12 inches of water in the depression on Tuesday. The high water mark, as indicated by silting on the ground cover, was slightly higher. There was no indication that runoff from the topsoil stockpiled nearby contributed significantly to the puddle of water. The developer stated that the stockpile will be removed in 2 to 4 weeks and has installed silt fence along the property line to control any erosion that may occur. City staff visited the site again on Wednesday afternoon during the rain and took photos of the situation. The property adjacent to the depression had been graded so that runoff from the development would drain away from the depression. There was water in the depression and in the drainage swale on the developer's property. City staff and the developer met Mr. Halpaus on site on Thursday morning. The developer volunteered to dig a sump to collect runoff from his site. Mr. Halpaus did not believe that this was enough to remedy the situation, he wanted the city to pump out the water The proposed final grading plan for the development, see attached plan, includes an emergency overflow that will take some of water from this depression and drain it to the storm water system in Seven Oaks. The developer's engineer has supplied the attached letter addressing the situation. 04: 0~ Schoell & Madson, Inc. Enginem"'ing ~' Suture/lng · Planning Sail T~l:ing ~ Environmental ,$ervi~ea www. 6choellmad~on. c~rn P. 02 April 12, 2001 Mr. Terry Maurer Howard R. Green Company 1326 Energy Park Drive St. Paul, MN 55108 Subject: Windsor Oak Hill Dear Mr. Maurer: Enid i~ the existing topography for/he Iow area behind future Lot 5, Block 1, of the W'mdaor Oak Hill plat. The topography indicates a land-locked Iow area which is, for the most part, on the adjoining property to the west. The bottom of the Iow ama as shown is 930.6. The topography indicatel the overflow from this Iow area is 934.7. This wouM mean the water would need to rise four feet to go over the owrtlow. Approximately six ac,-~,~ presently drain to this ama. Since the area does not have an outlet to the east lower than the 934.7 overflow, the Iow area most likely ponds slxing runoff until the fro~t has left the ground. This is a pre-existing condition. The water elevation on April 11, 2001 was 931.8. The proposed area of the Windsor Oak Hlii draining to lower ama will be less than what is presently draining there, The proposed storm sewm' outlet between ~ 5 and 6 will be at 932.0. This outlet will provide an overflow 2.7 feet below the existing conditions. Sincerely, $CHOELL & MAD$ON, INC. Doug Stahl, P.E. DAWcj cc: Ron Bastyr APR-l~-2001 04:04 P. 03 X 14, 7 933. 7 944, 5 ,xcj44 TOTRL P.03 956. EXISTING CONDITIONS 7 SETBACK ,/ if' C PROPOSED GRADING )UTLET ELEVATION ldo OF--~ 4 \ ! .-.. REI'AJ NI / / \ / / / !