EROSION CONTROL STRUCTURES

EROSION AND EXCESS RUNOFF ARE PRODUCTS OF MANY FACTORS: SOIL TYPE, PLANT COVER, CROPPING PRACTICES CLIMATIC ZONES, RAINFALL AMOUNTS AND INTENSITIES, AND DEGREE AND LENGTH OF SLOPE TO NAME A FEW. WATER EROSION USUALLY OCCURS AS SHEET EROSION, WHICH IS THE PERODIC REMOVAL OF THIN SHEETS OF SOIL OVER AN AREA, OR AS GULLY EROSION THAT FORMS INCISED CHANNELS. THE END PRODUCT IS SEDIMENT. IT IS IN THE CONSTRUCTION STAGE THAT NATURAL CONDITION SUCH AS TOPOGRAPHY, NATURAL COVER, SOIL CONDITIONS, AND DRAINAGE PATTERNS ARE BEING DISRUPTED DUE TO MANIPULATIONS BY MAN AND MACHINES. IT SHOULD BE THE GOAL OF EACH DESIGN AND CONSTRUCTION ENGINEER TO CONTROL THESE RESULTS WITHIN REASONABLE LIMITS DURING THE CONSTRUCTION STAGE AND FINALLY TO PERMANENTLY STABILIZE THE AREA FOR CONTROL OF EROSION AND RUNOFF UPON COMPLETION OF THE JOB. THERE ARE A NUMBER OF BASIC PRINCIPLES FOR CONTROLLING RUNOFF AND EROSION THAT HAVE PROVED SOUND OVER THE YEARS FOR OTHER LAND USES AND THAT CAN PROVE TO BE JUST AS USEFUL FOR HIGHWAY CONSTRUCTION. THESE INCLUDE SUCH THINGS AS PROPER ATTENTION TO SOIL, FOUNDATION, AND TOPOGRAPHY IN SITE SELECTION; MINIMUM EXPOSURE OF BARE AREAS BY CONTROL OF CLEARING AND GRADING OPERATIONS; DIVERSION OF WATER AWAY FROM CRITICAL AREAS; FLATTENING SLOPES; REDUCING SLOPE LENGTHS; USE OF TEMPORARY COVER; AND CONTROL OF EQUIPMENT ACCESS AND TRAVEL WAYS. A NUMBER OF STRUCTURAL MEASURES ARE DISCUSSED THAT MAY BE USED AS EITHER TEMPORARY OR PERMANENT INSTALLATIONS. THESE INCLUDE SUCH THINGS AS GRASSES OR PAVED WATERWAYS, BURIED PIPE OUTLETS, DIVERSION TERRACES, BENCHES, VARIOUS TYPES OF GRADE CONTROL STRUCTURES, CHUTES, INLETS, AND DEBRIS BASINS. /AUTHOR/