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I I I I I I !I I I I I II I I I I I I I required. As indicated in Section 6.2, use of off-site soils in the river will precipitate the need for the 404 Permit. After excavation of the trench, the pipe will be placed directly on a series of temporary supports elevating the pipe approximately one foot from the bottom of the trench. After the pipe is placed, prior to filling in the trench with the native river bottom material, the pipeline will be encased in concrete. The concrete placed around the pipeline will be placed at a minimum thickness of I foot around the pipe. The pipeline construction will continue in this manner for the other half of the river. No foreign material, with the exception of the concrete, shall be used as fill material to cover the pipe in the river section. The Colorado River Banks at the location of pipeline crossing will be armored utilizing 18-inch size rip-rap material. Section 0-0', as presented on Figure 6.5, is typical of pipeline construction in the area from Station 767 + 25 to Station 810+ 25. This section presents a conceptual detail of the pipeline trench adjacent to the railroad R.O.W., which is similar to the type of construction in section A-A'. This section will have construction considerations similar to those presented for the pipeline along Plateau Creek section C-C'. As indicated in Section 6.3, there are two channel outlet structures along the proposed pipeline alignment which require the jacking method of pipeline placement. Section E-E' as presented on Figure 6.6 is typical of pipeline construction in the area from Station 810+25 to Station 816+25. This section presents a conceptual detail of the pipeline trench at downstream Colorado River and 1-70 crossings. This area will present similar construction considerations to those encountered in the upstream Colorado River and 1-70 crossings. 6.6 Maintenance Considerations No extraordinary maintenance requirements are anticipated with either the pipeline or pipeline easement area. The only maintenance that is anticipated will be periodic inspections. It is anticipated that these inspections will be yearly the first two or three years and then progress to a five year inspection schedule. The type of maintenance problems anticipated will be: erosion of pipe cover material in flood plain areas after major storms; scour problems at river crossings; and settlement of cover soil. Each of these problems can be corrected with minimal construction effort by district personnel. Additionally, it is anticipated that the maintenance road be located along the pipeline route on the western bank of Colorado River. This road will require regular grading and maintenance to maintain its condition. 39