REQUEST FOR CONSTRUCTION BIDS FOR GRADING, STREAMBED STABILIZATION AND FRENCH DRAIN CONSTRUCTION FOR ASPEN MOUNTAIN PROPERTY OWNERS ASSOCIATION

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1 REQUEST FOR CONSTRUCTION BIDS FOR GRADING, STREAMBED STABILIZATION AND FRENCH DRAIN CONSTRUCTION FOR ASPEN MOUNTAIN PROPERTY OWNERS ASSOCIATION I. GENERAL The Aspen Mountain Property Owners Association (hereinafter referred to as OWNER is requesting proposals for services related to grading, streambed stabilization and construction of a French drain. The purpose for the work is to aid in stabilizing a hillside that has moved and is impacting a current access road. These services will be provided as a four part construction project. This project includes grading and removal of sediment that has collected around the Aspen Mountain water tank and cleaning and painting of the area of the water tank that was buried by the removed soil, grading the surface of the landslide below the water tank access road to establish a smooth slope surface to improve drainage of surface runoff, reduce infiltration, and reduce erosion of the side of the road along the landslide head scarp, stabilization of the streambed below the landslide deposit and installation of a French drain along approximately 270 feet of the east side of the access road. GeoStrata is the Geotechnical Engineer and will act as the OWNER S Representative during construction. This document describes the nature of work to be performed and the proposal information required from interested contractors. II. PROJECT DESCRIPTION AND SCOPE OF WORK The project is located in Moose Hollow Creek on the northern side of the Aspen Mountain development east of Oakley, Utah in Summit County, Utah. See A-1 for a site map showing the location of the project. The tentative schedule for the grading, streambed stabilization and French drain construction services will start by September 21, 2009 and be completed within 20 working days. This schedule is preliminary and is subject to change, however, based on the site elevation, the need for stabilization prior to winter weather is imperative. A discussion of each of the three parts of the project is presented below: Grading around the above ground steel water tank: Due to erosion and surface water runoff sediment has accumulated around a portion of the outer surface of the water tank. The contractor shall remove all soils in contact with the exterior of the water tank wall and grade the surrounding ground surface to improve water flow around the water tank. The grading around the tank shall be done in a manor to reduce erosion around the water tank and direct surface flow of water runoff around the water tank. The exterior of the water tank wall in the area where soil is removed by the contractor shall be cleaned and any loose or flaking paint and rust removed from the water tank outer wall. New rust resistant paint which color is approved by the owner shall be applied to the cleaned off area of the water tank outer wall. All rock retaining or soil berms planned by the contractor to improve drainage around the water tank or to reduce erosion shall be approved by the Geotechnical Engineer prior to construction. All surfaces to be painted should be inspected by the Engineer prior to application of coatings. All coatings should be applied in accordance with the manufacturer s specifications. Allow sufficient time between coats to assure thorough drying of previously applied paint. The coating thickness should be to the manufacturer s recommended minimum thickness.

2 Grading of the landslide surface and stabilization of the roadway above the landslide head scarp: The contractor shall scarify and compact the ground surface along the toe or bottom of the landslide deposit to produce a smooth surface that grades into the ground surface along the stream channel below the landslide deposit. The ground surface in the area of the head scarp of the landslide deposit along the access road shall also be scarified and compacted by the contractor. The grading, scarification and compaction process should be limited in depth to no greater than 1 foot below existing site grade unless approved by the Engineer. Some moisture conditioning may be required to aid in compacting the surface soils. The purpose for the work is to aid in providing positive drainage across the worked areas and to minimize the surface infiltration of moisture. These two areas of the landslide deposit where scarification and compaction shall be performed are shown on s A-2 and A-3. In the head scarp portions of the landslide there are a number of open tension cracks in the soil that penetrate down into the ground surface. In the area of these tension cracks the contractor shall scarified the soil so that these open tension cracks are healed (closed) through scarifying the soils. The soil shall then be compacted back in place resulting in a surface that is tight and free from openings that could allow surface water runoff to infiltrate down into the subsurface. Compaction of these areas should be observed by the Engineer. After the surface has been compacted and observed by the Engineer the surface of the landslide deposit shall be graded by the contractor. A portion of the landslide deposit shall be cut and graded up and over the head scarp area that was scarified and compacted by the contractor as previously described. Refer to s A-2, A-3 and A-3b for a generalized detail of the head scarp area where scarification and compaction will be performed and the cut and fill areas are anticipated. This cut and fill material shall be graded into the edge of the road to produce a smooth, continuous surface from the edge of the road down over the landslide deposit to allow surface water runoff to run freely down the slope reducing infiltration of surface water runoff into the landslide deposit by removing areas where water can pond and stand on the landslide deposit. This fill shall also be used to stabilize the edge of the access road and prevent erosion or raveling of the road where the head scarp adjacent to the road currently is a near vertical cut 3 to 5 feet high. The soil graded up into the head scarp area shall be compacted by the contractor in loose lifts of 8-inches or less. The grading and compaction shall be observed by the Geotechnical Engineer. The surface of the access road from the water tank south, down hill past the south margin of the landslide shall be graded so that the road surface slopes gently (approximately 2%) away from the downhill side of the road and the landslide deposit. A small berm should be constructed on the edge of the roadway in this same portion of the road. The berm should be constructed on native material and should be approximately 8 inches in total height. The berm is designed to act as a gutter and direct surface runoff from the access road away from the landslide deposit. Once the scarp area grading has been completed and the road berm has been constructed, we recommend that a UV resistant 10 mil visqueen (liner) be placed from the edge of the road and extending down slope to beyond the scarp area (approximately 40 feet). The approximate location of this liner is shown on A-2. The liner should be anchored in the roadway

3 with a trench a minimum depth of 1 foot. The liner should be restrained from movement through the use of sand bags. The sandbags should be spaced no greater than 20 feet in either direction. The final location of the liner shall be observed and accepted by the engineer. We further recommend that a row of sand bags be placed at the down slope edge of the liner. The sand bags should be placed to intercept runoff from the liner prior to impacting the site soils. The sand bags should be sloped generally as presented in A-2 to direct runoff away form the toe of the slope. The Engineer shall approve final sand bags locations prior to placement and the sand bags should be staked in place. The result of this grading shall be a continuous, smooth, compacted slope that extends from the edge of the road down across the landslide deposit. This slope will be constructed to allow free flow of surface water runoff down and across the landslide deposit and shall not allow ponding of surface water on the landslide deposit. Surface water should run freely down slope, across and off the landslide deposit and eventually into the streambed below the landslide deposit. This grading will also result in stabilization of the west side of the road and will prevent raveling or erosion of the downhill side of the access road. Stabilization of the streambed below the landslide deposit: The stream below the landslide deposit has eroded the toe of the landslide deposit during spring runoff. The contractor shall excavate the current stream channel below the landslide deposit, along the alignment shown on A-2, deeper and wider to allow larger volumes of water to pass through the channel below the landslide deposit without eroding the channel or the toe of the landslide deposit. Large cobbles and boulders available on site shall be used by the contractor as rip-rap to stabilize the east side of the stream channel adjacent to the landslide deposit to prevent erosion and lateral movement of the stream channel during periods of high runoff. Construction of 270 feet of French drain along the eastern side of the access road: The French drain is to be constructed in the approximate area noted on A-2. The purpose for the French drain is to collect near surface water and surface runoff and direct the water away from the landslide deposit. The French drain shall be constructed as noted on the detail shown on A-5. The new French drain will overlap the alignment of the existing, non engineered drain currently in place at the site. The contractor shall remove all portions of the existing drain system that could in the Engineer s opinion adversely affect the new French drain. This would include the depth of the new trench, left over gravel, and pipe from the old drain system. The contractor shall provide a positive grade the length of the drain to minimize the potential for water to infiltrate into the subgrade. The utility locating of the existing waterline and associated data cable buried within the access roadway is the responsibility of the contractor. Repair of any damage to existing utilities shall be the responsibility of the contractor. At the south end of the French drain, as shown on A-2, the contractor shall convey the French drain across the access road in a solid pipe and daylight the pipe on the native slope west of the road. The drain pipe shall extend to the base of the slope where it can drain into the stream. The engineer

4 shall observe and approve the construction of the French drain termination and the extension of the drain pipe across the access road. Submittals of all materials to be used in construction of the French drain shall be approved by the engineer prior to placement. III. CONTRACT The contractor will be required to enter into a contract with the OWNER to provide grading, streambed stabilization, road improvements and construction of the French drain. The contractor shall note any exceptions to the contract when it is provided for review and signatures. IV. FEE SCHEDULE The contractor shall provide the OWNER with a fee schedule for the proposed scope of services. The fee schedule shall be the agreed unit price for the duration of the project. Over run and under run of quantities of 50% may be grounds for renegotiation of the unit price. The discovery of quantity over runs or under runs shall be communicated in writing to the OWNER. The unit price provided by the contractor to the OWNER shall include all incidental costs required to complete the work scope of the project. This shall include labor, materials, equipment, mileage and other items necessary to complete all the above outlined work scope. ATTACHMENTS A-1 A-2 A-3 A-3b A-4 A-5 Site Vicinity Map Site Improvement Map Landslide Grading and Compaction Profile Projected Post Compaction Profile Topographic Profile above French Drain Cross Section of French Drain

5 Subject Site Location Aspen Mountain Homes Moosehollow Creek Highway ,000 2,000 3,000 4,000 Feet 1:18,000 BASE MAP: USGS Topographic Map Copyright GeoStrata, LLC 2009 Aspen Mountian HOA Oakley, UT Site Vicinity Map A - 1

6 A B' B A' Legend Note:locations of features on map are approximate Landslide Scarps Area of scarification /compaction Feet Section of stream to be stabilized Exisiting French Drain 1:1,000,000 Line of Sand Bags location of stream Trough dug to secure liner Liner boundary BASE MAP: 2006 NAIP Copyright GeoStrata, LLC 2009 Aspen Mountian HOA Oakley, UT Site Improvement Map A-2

7 B Landslide Grading and Compaction Profile B Location of attachment A-3b Current Topography Area to be compacted and scarified Fill to be added to grade the landslide surfaceand stabilize the toe and west side of road. Copyright GeoStrata LLC 2009 CROSS SECTIONS Oakley Landslide Aspen Mountain HOA Summitt County, UT A-3

8 B Projected Post Compaction Profile B Liner to be placed atop the graded landslide. Small berm to be constructed at top of landslide. Line of sand bags to be placed at end of liner. Liner to be placed at base of 1 foot trough to secure Position. Projected topography after compaction and grading Copyright GeoStrata LLC 2009 CROSS SECTIONS Oakley Landslide Aspen Mountain HOA Summitt County, UT A-3b

9 Elevation (ft) Topographic Profile Above French Drain A A Distance (ft) Copyright GeoStrata LLC 2009 CROSS SECTIONS Oakley Landslide Aspen Mountain HOA Summitt County, UT A-4

10 Cross section of French Drain 6 inches 6 inches Clean Gravel Notes Geo Fabric 1-Geofabric should consist of Mirafi 140 N or Equivalent. 2-Geofabric should overlap to meet manufacture recommendations 3-Clean gravel should have 100% passing the 1 inch sieve and less than 5% passing the no. 4 sieve. 4-6 inch perforated pipe should have perforations continuous around the circumference. 5-Bottom of trench should be graded to rapidly drain collected water to discharge point without ponding. Clean Gravel 6 inch perforated pipe 2 ft 4 ft Copyright GeoStrata LLC 2009 CROSS SECTIONS Oakley Landslide Aspen Mountain HOA Summitt County, UT A-5