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Consideration should be given to including provisions in the contract requiring <br />• stocl-piling of stone during the eazly stages of construction for use at pipe out]eu, ditches and <br />other locations where erosion problems may develop. <br />Temporary divcrsion channels are used when it is necessary to divert water around an <br />area where a culvert in to be constructed. Often times the raw erodible slopes of these <br />channels contribute to siltation. Figure A-20 (page A-34) suggests using stone linings with <br />gravel foundations for erosion control in lazge diversion channels and gravel lining for smaller <br />channels. On those projects where rock excavation is encountered, ledge fragments should <br />be stockpiled for use in lining channels, ditches, pipe outlets, and for constructing haul roads <br />across streams. Temporary stone or hay bale check dams placed in the diversion channel can <br />also effectively minimizt siltation. <br />Hazardous conditions can be seated not only by the hauling activities but also from <br />the silt laden runoff that is discharged from the haul road onto the ]ocal street. Quite often <br />sediment is deposited in street drainage systems and ultimately carried to a nearby wattrway. <br />• Tempozary erosion and siltation controls should be included at these locations. One <br />method that can be employed is to constzuct a sag in the haul road profile, install a temporary <br />pipe under the road and direct zunoff to a temporary sediment pool. Similar structures can be <br />constructed at stream and river crossings. <br />The ideas and suggestions presented in this booklet depict many of the temporary <br />measures that have been used successfully in minimising soil erosion and water siltation <br />re'.ated to highway construction activities. In some instances, these temporary controls are <br />being included in the project plans. <br />The features shown in this booklet will apply to other conditions besides those <br />discussed. There are many situations which occur on a typical highway construction project <br />where erosion and pollution problems become evident and some type of temporary control <br />should be provided. The features discussed in this booklet aze just some of the items that <br />have been successful and should be considered. Bridge construction, borrow pits, waste azeas <br />and haul roads off the right-of-way are some other azeas where the features discussed in this <br />booklet could be used effectively. <br /> <br />A-9 <br />