Using the ANSWERS model to estimate sediment yields on construction sites

ABSTRACT:

ANSWERS (Areal Nonpoint Source Watershed Environment Response Simulation), a model used primarily to assess the impacts of alternative management schemes on agricultural land, was selected for a study of solutions to runoff and erosion problems associated with construction activities. Several management alternatives, using both conventional and unconventional runoff and sediment control practices, were evaluated. These were compared to each other and to preconstruction responses of the watershed using a design storm concept. Some typical construction practices that left the soil in an exposed, disturbed state resulted in sediment yields exceeding those under the area's original row-crop configuration. None of the management alternatives considered erosion from spoil piles or active gully head cuts. Other practices, such as seeding exposed areas and graveling roadbeds and exposing as little soil as possible, resulted in much smaller soil losses. Such structural measures as sediment basins and diversions produced variable sediment yields. These results, while preliminary, point out the applicability of ANSWERS in construction site planning. They agree with the meager data collected to date on sediment yield at construction sites.