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Attachments to Minnesota LocaUState/Federal Application Form for Water/Wetland Projects Re-establish Outlet for West. Vadnais Lake Ramsey County Department of Public Works 5. PROJECT PURPOSE, DESCRIPTION AND DIMENSIONS This proposed project involves the reestablishment of downstream hydrology for the West Vadnais Lake sub watershed, which is now landlocked, by the construction of a control structure at 881.9 (MnDOT/ NAVD 1988 datum) at the south end of the wetland connected to W. Vadnais by a culvert pipe-under Vadnais Blvd., that would flow into a pipe connection under Interstate 694 to County Ditch 16. Historically, West Vadnais Lake outlet to the south through a wetland complex and into the precursor to County Ditch 16, and thence to Gervais Lake. Construction of I-694 in the 1960's blocked this flow path. A Grass Lake WMO (GLWMO) report in 1990 identified the outlet from West Vadnais Lake through a ditch and pipe to Twin Lake (in the Ramsey-Washington Metro WD) just north of I-694. This secondary outlet was filled in by debris from building demolition at some point and there is no effective remaining connection to Twin Lake. The West Vadnais Lake sub watershed is land-locked. Water levels in W. Vadnais and the connected wetland have increased over the last several years, reaching within 0.5 feet of the centerline of a County road, Highway 49 (Rice Street) at the north end of W. Vadnais Lake and in the vicinity of a railroad overpass. This high water in the vicinity of Highway 49 threatens the integrity of the road sub base. Potential flooding of the roadway is a safety hazard and would. disrupt traffic on this arterial road. St. Paul Regional Water Services has also experienced high water at their Vadnais Lake pumping Station, located along the east edge of W. Vadnais Lake. Ramsey County and St. Paul Regional Water Services have requested MnDOT to provide engineering services for the feasibility analysis-and design of the proposed West Vadnais outlet structure, pipe alignment, and pipe maintenance access options. There is a brief opportunity available to re-establish a flowage for W. Vadnais across I-694 prior to the reconstruction of this section of I-694 scheduled for 2005. Proposed plans include an outlet control elevation at 881.9 (MnDOT/ NAVD 1988 datum}, .based on a 1990 GLWMO report (Level Control Plan, April 19, 1990) that identified 881:9 (NAVD 1988 datum) as the normal water level for W. Vadnais Lake. The Minnesota DNR survey report for West Vadnais (Minnesota DNR Waters Field. Survey Report, West Vadnais Lake, November 14, 2003) also stated that the proposed control elevation of 881.9 (NAVD 1988 datum), which would equate to 881.7 in NGVD- 1929 datum, would be reasonably consistent with the O.H.W. level of 882.5 (NGVD- 1929 datum). The outlet control structure would be a pipe. and apron set at 88L9 (NAVD 1988 datum). A ditch to be constructed approximately 150 feet in length would join the outlet structure to the south edge of West Vadnais Lake. The pipe would be 15-inch diameter, the minimum size needed to allow for maintenance, with a maximum flow rate of 4 cfs (pipe full condition). The downstream outflow of the pipe would be to a ditch located. on the south side of I-694 located between old Knox Lumber and Levitz