EVALUATION OF RECENT TECHNOLOGY FOR INSTALLATION OF SUBSURFACE DRAINAGE IN EGYPT

Abstract

IN Egypt approximately 1.75 million hectares has been provided with subsurface drainage. When the construction of drainage systems reached the fringes of the Nile Delta, unstable soils and heavy sticky clay soils were encountered. The commonly used trenching technique faced substantial construction problems when such soils were encountered. The trenchless drainage system technique executed with the V-plow type of trenchless machine provides a good alternative. A Y-plow trenchless drainage machine was imported and used under Egyptian irrigated field conditions and was thoroughly tested. A total of 141 km of lateral drains were constructed during a 13 weeks

period, in semi-unstable, medium textured and fme textured soils. During the experiment, extensive data were collected on the performance of the machine. Speed and production of the \"-plow are tested against depth, soil type, soil moisture status, soil resistance. land surface condition (wetness, type of crop). number of irrigation canals to be crossed, days after irrigation, and experience of the operator. It was found that the production per hour of the trenchless machine was

1.6 times higher than the trencher machine. The installation costs per kilometer length of drains with the trenchless machine proved to be 25% lower than the trencher machine. No difficulti es were encountered in any of the soil types and virtually no machine maintenance was needed. However. also some disadvantages of the trenchless technique were observed: (i) an excavator is required full time, (ii) not all wet (irrigated) fields could be crossed (approx. 1 % of all drains), and (iii) visual inspection of the installed drains was not possible. The trencherless experiment was considered successful to be applied in similar soils in Egypt.