1. GEOLOGY RECOMMENDATION SHEET GEOLOGY NOTESGEOLOGY RECOMMENDATIONS WYOMING DEPARTMENT OF TRANSPORTATION MATERIALS TESTING LABORATORY PROJECT __________________________________ A.F.E. NO.__________________________________ TOTAL SHEETS SHEET NO. 112 STREET ABC-123 Embankment Clean onsite soils, or approved import materials may be used as fill in embankment areas. Cut/Fill Slopes Fill slopes of 3H:1V or flatter, are recommended for permanent slopes in compacted fill areas. If steeper slopes are required, stability analyses should be performed for the design grading plan. The face of all slopes should be compacted to the minimum specification for embankments. Alternatively, fill slopes can be over-built and trimmed to compacted material. Borrow Areas The borrow areas proposed for use as fill are located within the right-of-way adjacent to the alignment. The borrow areas are comprised of potential vertical alignment cuts. The material encountered in the soil borings within the borrow areas consists of clayey to silty sand, sandy clay with gravel, and silty to clayey gravel. Stripping In areas of proposed widening, strip and remove all existing vegetation and any deleterious materials from the proposed pavement areas. Existing asphalt/basecourse section should also be stripped and, if needed, stockpiled and re-used as base course. Stripped materials consisting of vegetation and organic materials should be wasted from the site, or used to re-vegetate landscaped areas or exposed slopes after completion of grading operations. If unexpected fills or underground facilities are encountered during site grading activities, such features should be removed and the excavation cleaned prior to placement of backfill and/or new construction. All excavations and exposed subgrade should be observed by the Engineer prior to fill placement or construction. Excavation It is anticipated that the excavations for the proposed construction can be accomplished with conventional earthmoving equipment. Subexcavation It is anticipated that the subgrade conditions in most areas will be relatively stable, however, there may be exceptions. In addition, the stability of the subgrade may be affected by precipitation, repetitive construction traffic, or other factors. If areas are encountered where the exposed subgrade is unable to support heavy construction traffic, the soft soils can be subexcavated and replaced with granular fill, as directed by the Engineer. Subgrade treatment of soft areas could include the removal of unsuitable soft material to a minimum depth of 24 inches and backfilling with a Pit-run select material. Prior to placement of the backfill material a non-woven separation fabric should be placed directly on the exposed subgrade. Based on an assumed 2% of the project alignment needing subexcavation, quantities are estimated as follows: Subex,(cy)Separation Fabric, (sy) 500 600 The scope of the soil survey services performed for the proposed alignment included site reconnaissance by a geotechnical engineer, a subsurface exploration program, laboratory testing and engineering analysis. Based on the information provided, it is our understanding that the project will consist of the reconstruction of approximately 1.64 miles of Highway 310 through Cowley, Wyoming. The centerline will shift approximately 10 feet to the north within the town and the southern portion of the project will be lowered approximately 2 to 3 feet to accommodate the placement of curb and gutter, which will provide drainage of adjacent properties. The project will also include the possible extension of the existing box culvert and reconstruction of the downstream wingwalls on the west end of the project, the extension of water/sewer lines running parallel to 4th Street South, and the exploration for visual detection of potential hydrocarbon contamination in the vicinity of specific properties as identified by the District Engineer. The twenty-six (26) soil survey borings for the alignment were performed on October 10th through October 12th, 2005. The borings were advanced to approximate depths of 11.5 to 21.5 feet using a truck-mounted, BK-81 drilling rig utilizing hollow-stem augers at select locations. At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring barrel samplers. Penetration resistance measurements were obtained by driving the split-spoon samplers into the subsurface materials with a 140-pound hammer falling 30 inches. In addition, two (2) hand auger borings were obtained on October 13th, 2005, near station 181+80 near the existing culvert. The hand auger borings were advanced to approximate depths of three to four (4) feet utilizing a 3-inch- diameter hand auger. Penetration resistance measurements were obtained in the hand auger borings using a dynamic cone penetrometer. The project area is located in the City of Cowley, Wyoming and lies within the Bighorn Basin. The elevation of Cowley is approximately 3,990 feet above sea level with a high, generally eastward-sloping surface which is underlain by alluvial deposits. The ground surface has a gently rolling topography of low to moderate relief. The thin surficial alluvial deposits in the Cowley area are underlain by Upper Cretaceous sedimentary rocks of the Cody Shale Formation. The existing roadway surface along the alignment consists of about 5 to 7 inches of asphalt pavement underlain by about 1.3 to 2.7 feet of base course. Embankment fill, deposits of sands with various amounts of clay and gravel, clays with various amounts of sand and gravel, and gravel with varying amounts of sand and clay were encountered along the alignment. In select areas, claystone bedrock was encountered below the overburden soils. Groundwater measurements were made in each boring at the time of exploration. Groundwater was observed at approximate depths of 7.5 to 11.0 feet in borings performed at approximate stations 177+00 through 169+00, 157+00 through 145+00, and 133+00 through 101+00. Groundwater was not observed in the borings performed in the remaining sections of the alignment. Pit-Run Subbase Pit-Run aggregate used in stabilizing soft subgrade soils should meet the following grading requirements, or an approved equivalent: Sieve Size%Passing 6”100 3”60-90 1 ½”40-70 #430-50 #2000-15 The pit-run grading requirements may be modified if approved by the Engineer. Shrink/Swell PreparedApproval