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1993-09-10 Feasibility Studies Water/Sanitary Sewer ImprovementsMEYER-ROHLIN, INC. ENGINEERS-LAND SURVEYORS 1111 Hwy. 25 N., Buffalo, Minn.55313 Phone 612- 682-1781 September 10, 1993 City of Albertville c/o Lirda Houghton, Clerk Box 131 Albertville, MN 55301 RE: Feasibility Studies for I-94 Watermain Crossing and for Water and Sewer along the Frontage Road north of I-94 Honorable Mayor and City Council: As requested, we have-completed the Feasibility Studies for the water and sanitary sewer improvements for the above-referenced projects. PROJECT LGCATION The I-94.watermain crossing would be located under I-94, just north ~f Main Street where ari exis~ing 21-inch casing was previously placed prior to the highway being constructed. k~atermain and sanitary sewer would be placed along the service road north of I-94, from the intersection with CSAH 37 to the end of the service road between Mud Lake and School Lake. The project would be located in the North Half of Section 1, Township 120, Range 24, Wright County, Minnesota. See Attachment 1. I-94 WATERMAIN CRGSSING Prior to I-94 being ccnstructed, the City placed a 21-inch Thore P. Meyer, Professional Engineer Robert Rohlin, Licensed Land Surveyor i reinforced concrete pipe across the I-94 right-of-way. This was intended to eventually be used as a casing pipe for a watermain which would service the area north of the Interstate. Normally the casing pipe should be six to ten inches larger than ' the carrier pipe. This allows room for the bells on the ends of i each section of pipe. Skids are attached to the carrier pipe so that it can slide into the casing more easily during installation. These also take up some of the area of the casing. If the existing casing was in good condition, the maximum size ductile iron carrier pipe that could be installed would most likely be a 12-inch pipe. The existing casing is not in good condition, however. It was apparently damaged from highway construction. The casing pipe has been exposed, cleaned out, and elevation and alignment shots taken at approximately 6-foot to 8-foot intervals through the 260 feet of casing length. A drawing of the pipe has been plotted at a large scale and templates of various size pipes superimposed upon the casing pipe alignment. It would appear that a 10-inch ductile or PVC may be possible, however questionable, or an 8"inch ductile iron or PVC pipe, being rigid pipes with very limited flexibility at the joints, would be the maximum size that could be installed. We have explored the use of a polyethylene pipe, which has just recently been approved by AWWA and Minnesota Health Department for use in watermain installation. A request would need to be made to Joint Powers Water for their approval. Polyethylene pipe is a fusion jointed, relatively flexible pipe, which would eliminate the extra diameter for the hubs at the joints and also give some flexibility to follow the misalignments and displacements of the existing casing pipe. [ + ~ .! T'r.e following table is a comparison of pressure losses through 300 feet of various pipes and sizes for the carrier installation, using a fire flow of 2,500 gpm. Pressure 1 Loss/300' Comments Ductile Iron CL. 52 12" (12.46 I.D.) 2.48 psi size too large 10" (10.40 I.D.) 5.97 psi size questionable 8" (8.39 I.D.) 16.94 psi size ok 4~ ~~=0 12" (1165 I.D.) 1.62 psi size too large 10" (9.79 I.D.) 3.78 psi size questionable $" (7.98 I.D.) 10.20 psi size ok :'.E. 16" OC (13.090 I.D.) 0.93 psi size questionable 14" OD (11.454 I.D.) 1.77 psi size ok 12" OD (10.432 I.D.) 2.79 psi size ok As the IO-inch DI, 10-inch PVC and 16-inch PE are questionable s_ze pipes, it would appe ar that a 14-inch OD P.E. pipe wculd be the most favorable for this situ ation. Pressure losses at various flows through the 14-inch PE pipe for the 300-foot crossing length would be: 1000 gpm 0.32 psi 2500 gpm 1.76 psi 3500 gpm 3.28 psi 5000 gpm 6.35 psi As can be seen the pressure losses at the normal flows are very minimal and for the extremely high fire flows are not excessive. I-94 FRONTAGE ROAD WATERMAIN The watermain would be placed on the north side of the frontage .road, from the western end to across CSAH 37, see Attachment 2. It ;vould consist of approximately 2700 feet of 12-inch ductile iron a I"•{R., ;t • J • r ,: ~` '. ' I ~/ or FVG pipe. Hydrants would be placed in accordance with Joint Powers' requirements. Services would be extended to the property T lines for the lots along the frontage road. The CSAH 37 crossing i wculd consist of approximately 70 feet of steel casing with a " 12-inch. carrier. The casing and carrier would be jacked and bored under the highway. ~~_o ;: s~p~l;'=,CE RCAD SPJ~ITARY SEWER ~~ __ ~,:~e sanitary sewer would also be placed on the north side of the ;:ror_t,age road, from the western end to across CSAH 37, see :attachment 2. It would consist of approximately 2700 feet of i2-ir_ch PVC sewer pipe. Services would be extended to the property li ~1Fs for the lots along the frontage road. The CSAH 37 crossing r~oul:~ consist of approximately 80 feet of steel casing with a 12-inch PVC. carrier. The casing and carrier would be jacked and bored under tine highway. ~iZe proposed invert elevation of the manhole at the western end of the sanitary sewer would be approximately 942.5. The ordinary high ~:~ater (0?~w1) level of the lakes is 947.3. The lowest floor elevation of any structure must be three feet above the OHW elevation., resulting in a minimum floor elevation of 950.3. fiherefore, the extent of gravity sanitary sewer into the area between School and Mud Lakes would be dependent upon the plat design, street grades, etc. This westerly line, however, would be ~he proposed outlet for any future upgrading of the forcemain from _, f;he ex~"sting lift station located in Sunrise Commercial Park, as has been discussed by Council previously. The proposed invert elevation at the easterly end of the sanitary sewer line is approximately 943.5, which would service all of the remaining developable property in Albertville above the wetland elevation of approximately 950.0 feet. ~.