APPLYING GEOSPATIAL TOOLS TO MODEL AND DISPLAY GROUNDWATER DATA AT A FOOD PROCESSING FACILITY LAND TREATMENT SPRAYFIELD, ELLENSBURG, WASHINGTON

Geospatial tools provide a relatively quick method to model groundwater (and soil) contaminant concentrations and to develop easy to understand site maps displaying this data. ESRI ArcGIS Geostatistical Analyst and Goldensoftware’s Surfer were employed to develop these types of products using existing groundwater monitoring data for a land treatment sprayfield utilized for disposal of food processing wastewater. The data was previously submitted to the Washington State Department of Ecology as part of state waste discharge permit submittals or other studies and is available to the public by website accessible databases.

A food processor located in Ellensburg, Washington utilizes a land treatment sprayfield for disposal of process wastewater. The sprayfield currently consists of 150 acres located along the Yakima River. Process wastewater is applied to the fields during the growing season when crops uptake and thus treat biological oxygen demand (BOD) and nitrogen among others.

A complicating factor with evaluating groundwater at the land treatment sprayfield is that a former cattle feed lot (Schaake property) was located to north and directly upgradient of the sprayfield. Impacts to groundwater from this former facility make it difficult to distinguish between historical impacts to groundwater from the former feed lot and the food processor land treatment sprayfield. It also makes it more difficult to determine if the current operations at the sprayfield are impacting groundwater. Historical operations at either facility could cause reducing conditions in the groundwater resulting in naturally occurring metals within the alluvial sediments (e.g. iron, manganese, and arsenic) to precipitate into the groundwater at elevated concentrations.

The U.S. Bureau of Reclamation is also in the planning phases of the Schaake Property Habitat Improvement Project (levee pull back) along the Yakima River that will most likely cause the land treatment sprayfield to be reconfigured. Groundwater modeling of the area within and nearby the land treatment sprayfield will be useful for planning the reconfiguration and to modify the state waste discharge permit to accommodate these changes.