03-08-1995 Council Agenda - Laserfiche WebLink

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Frattalone Sewer Extension City of Little Canada SANITARY SEWER IMPROVEMENTS Soils A 1989 subsurface investigation of the Ryan Industrial Park determined that it rests on very poor soils. Numerous borings were taken on Ryan Drive, Ryan Lane and Spruce Street in an effort to determine what types of construction would be required to obtain stable roads and utilities. It was determined that a cap of silty sands and fly ash had been placed on the surface in an effort to stabilize it for roadway and floating slab building construction. The subsurface, however, remains a formidable obstacle to the installation of utilities, particularly on the eastern half of the industrial park. Borings at the east end of Ryan Drive show peat and muck deposits up to 36 feet deep. This report assumes that soils encountered in the project area will be similar to that found in the nearest borings, approximately 300 to 600 feet away (on Ryan Drive, just west of Country Drive). Further borings will be necessary for the design stage. Installing gravity sewer in this type of material will require the use of pile foundations. This is necessary to minimize settlement related distress and because excavation of the organic soils and replacement with suitable soils is not feasible from an economic or physical standpoint. Floating a gravity line in a bed of timbers or Light weight aggregate is sometimes considered with organic soils. Unfortunately, this line must be placed at minimum grade (0.40 %) to serve all of the remaining properties. The tight tolerances required in placing a flat grade in unstable soils precludes this option. Another option that will be discussed in this report is floating a small diameter plastic force main in the unstable soils. Service To the Industrial Park As part of this report in order to install sanitary sewer in the proper location and depth we reviewed the current status of sewer service in the industrial park (see Figure 1). We found that the western half of the park is currently served by a Metropolitan Council interceptor line beneath Spruce Street. The eastern half of the park has two sewer lines in the area: an 8" service line to Levitz and a 42" Metropolitan Council interceptor line east of Country Drive. The Levitz line is too shallow to serve the eastern half of the industrial park by gravity sewer. The Met Council line offers the most practical means of providing gravity sewer service to the eastern half of the industrial park. If placed at minimum grade, it appears that a gravity line connected to the Met Council line may be able to serve all remaining unsewered properties in the industrial park. The ability to serving Lot 1 of Block 1 with gravity sewer is uncertain and would require survey work to determine. 37225.rpt 4 Page 9