Wastewater application by spray irrigation on a field southeast of Tallahassee, Florida: Effects on ground-water quality and quantity, 1980-82

Abstract

1009 ____ . _____ ____ ___ _. . ____ ___________________________ 97 J_ .7 O ^ ___________________________ __ 4* *J 1 UP! 1 JL VT W .^ .1.2. Data-collection frequency range and analytical procedures for chemical constituents 14 IVTemperature units are converted from degrees Fahrenheit (°F) to degrees Celsius (°C) by the formula °C = 5/9 (°F -32); from degrees Celsius to degrees Fahrenheit by the formula °F = 9/5 (°C + 32). ABSTRACTAn 1,840-acre agricultural field southeast of Tallahassee, Florida, which has been used for land application of wastewater by spray irrigation, is the site of a long-term, ground-water monitoring study. The purpose of the study is to determine effects of wastewater application on water-table elevations and ground-water quality. The study was conducted in cooperation with the City of Tallahassee. This report summarizes the findings for the period 1980-82.Wastewater used for spray irrigation has high concentrations, relative to those in ground water, of chloride, nitrogen, phosphorus, organic carbon, coliform bacteria, sodium, and potassium. At most locations, percolation through the soil has been quite effective in attenuation of these substances before they can impact the ground water. However, increases in chloride and nitrate-nitrogen were evident in ground water in some of the monitoring wells during the study, especially those wells which are within the sprayed areas. Chloride concentrations, for example, increased from approximately 3 milligrams per liter to 15 to 20 milligrams per liter in some wells and nitratenitrogen concentrations increased from less than 0.5 milligrams per liter to 4 milligrams per liter or more.Ground-water levels in the area of the spray field fluctuated over a range of several feet. These fluctuations were affected somewhat by spray irrigation, but the primary control on water levels was rainfall.As of December 1982, constituents introduced to the system by spray irrigation of effluent had not exceeded drinking water standards in the ground water. The system has not yet stabilized, however, and more changes in ground-water quality may be expected.