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Scope of Work <br />Page 5 <br />3.3.6. Drain System - On completion of several concrete <br />wall panels, a drain will be installed behind the <br />wall. The drain will run the full length of the wall <br />and up the face of the wall as shown in Drawing # <br />2202.2. The drain will consist of 8 inch perforated <br />PVC pipe surrounded by 1" - 1 1/2" washed rock. The <br />lower portion of the drain will be wrapped with Mirafi <br />140 N filter fabric (see Drawing # 2202.3). The washed <br />rock will be placed in a 1 foot thick blanket from the <br />wrapped pipe drain to the surface just behind the face <br />of the wall. The drain will daylight at the east end <br />of the wall. A pipe or lined ditch to carry run-off <br />down the slope will be installed. <br />3.3.7. Retaining Wall Backfill - Retaining wall backfill <br />will be sequenced in manner such that installation of <br />the 2 pipelines, tiebacks, and drain systems can be <br />accomplished. Backfill will be compacted to 958 <br />maximum dry density.Compaction tests will be taken. <br />3.3.8. Waterline Relocation - The existing temporary 8 <br />inch raw waterline and the existing 2 inch fresh <br />waterline will be relocated out of the landslide area <br />and placed behind the retaining wall. The 2 pipes <br />will be buried their entire length to prevent <br />freezing; burial depth will be a minimum of 6 feet, <br />colored plastic marker tape will be placed at a depth <br />of 2 feet. A manhole will be installed at the lower <br />tie in to access shut-off valves. The manhole will <br />consist of a 48 inch corrugated metal pipe with a <br />concrete top and cast iron manhole cover (see Drawing <br />#2202.4). The pipe to be used for the relocation will <br />be Victaulic coupled steel pipe with a coal tar epoxy <br />exterior coating. Concrete thrust blocks will be <br />installed as shown on Drawing # 2202.5. <br />