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HomeMy WebLinkAbout12-11-1990 - Re: Woodhill CC sewer connec. COFFIN & GRONBERG, INC. SURVEYING,ENGINEERING AND LAND PLANNING 482-A TAMARACK AVENUE LONG LAKE,MINN.85388 473.4141 December 11, 1990 City of Orono P. 0. Box 66 Crystal Bay MN 55323 Attn: Mark Bernhardson and John Gerhardson Re: WOODHILL COUNTRY CLUB SEWER CONNECTION Dear Mark & John: We first looked at the possibility of using a new drainfield system to treat the effluent from Woodhill Country Club. After having Woodhill install a water meter, we found that peak flows exceed 11,000 GPD. Mound systems can only handle 1,000 - 1,200 GPD in any one location because any additional volume raises the groundwater elevation under the mound area causing hydraulic fail- ure. This is known as "groundwater mounding" . Thus, we would need about 10 different sites to put in the mounds required. Most of the Woodhill site is wooded, hilly, prone to flooding or is located in golf fairways, greens or tees which makes it in- appropriate for drainfield systems (as shown on attached Exhibit A from a 1978 drainage study) . It would be very difficult to find enough areas meeting the criteria for mound systems. Constructing a pumping system to reach 10 remote and separate mound sites would be very complex and disruptive to the grounds and golf course. After checking with the City of Wayzata, we found two pos- sible connections to their sewer at this time. One connection would be near the lift station just south of Wayzata Country Club near old Highway 12, and the other being south of County Road 15 at the west end of Peavey Lane near the cul-de-sac. The first option to the lift station would involve ap- proximately 4,000 feet of sewer line with jacking required under the Burlington Northern Railroad, NEW U.S. Hwy. No. 12 and OLD U.S. Hwy. No. 12, and would also involve getting approval from those owners as well as approval from Wayzata Country Club to cross their parcel between the two highways. Also, some pumping stations would be needed and depending on the route allowed ( if at all) , some unsuitable soils and additional length could be encoun- tered. The second option to Peavey Lane would involve cutting through the center of the golf course with its many irrigation and draintile lines, under the Dakota Rail, West Lake Street and County Road No. 15 and then through private property to Peavey Lane. This would entail about 3,600 feet of sewer line depending on the route chosen. Soil borings from the 1978 drainage study indicate areas of 15 to 17 feet of peat soils close to the Dakota Rail crossing. Similar conditions may exist in other areas as well as in the lower areas near County Road No. 15 and Peavey Lane. This would be a very difficult line to construct and very destructive to the golf course. Both options are shown on the en- closed aerial photo copies. The proposed Orono connection could be accomplished by grav- ity flow after a short pumping distance from the present septic tank area to a new manhole in the parking lot. Very little dis- ruption to the golf course and existing vegetation would occur and soil borings have indicated much more suitable soils for construc- tion of the sewer line. Please contact me if you have any further questions. Sincerely, COFFIN & GRONBERG, INC. Mark S. Gronberg c7 MSG/lh Enclosures