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four times the height of the structure. If available, polyethylene sheeting can be used to protect the river side of the expedient levee from erosion and reduce seepage. Another alternative to limit erosion is to cover the river side slope of the expedient levee with sand bags. Expedient Levee Advantages: ,j Relatively easy to construct ,j Can be rapidly built with heavy machinery ,j Height may be easily raised if necessary Disadvantages ,j Right of ways required for placement ,j Access required for heavy machinery ,j Area must be left for machinery passage Often expedient levees are constructed along roadways. The road surface provides a sound base for the structure and allows easy access for construction equipment. If the road is level, Jersey Barriers have been used by a few communities with some success. _. _ ___~. _ _.Ih.eJ2arriexs rQl!.)'.I2e readily available in the communit~d if properly placed they seem to offer an effective means of expedient protection where only three feet or less of added protection is required. As with all expedient levees, a survey shOuld be performed before placement to assure that the level of protection given by the barriers will be sufficient for the expected crest. This method is only suitable for flat areas. It is absolutely essential that the barriers be anchored to prevent movement when they are exposed to the tremendous forces of the flood waters. The barriers should be locked to each other by cables or pins and further anchored to the ground with drive spikes or pins through the anchor holes provided in the barrier. Two rows of barriers are used side-by-side and filled with tamped earth. If available, polyethylene can be placed under the river side barrier and draped over the works to reduce water infiltration. A row of sand bags may then be place at the base of barriers to secure the Page 4 - 10 Notes