Use of a Geo Flowmeter for the Determination of Ground Water Flow Direction

Abstract

AbstractThe Geo Flowmeter is manufactured by K.V. Associates of Falmouth, Massachusetts, and is used to determine ground water flow direction and velocity in monitoring wells or open boreholes. It operates by emitting heat pulses and measuring subsequent temperature increases carried by the ground water movement. The meter can be used in wells as small as 2 inches in diameter and only a single well is required for determination of ground water flow direction and rate.This paper is a case history of the use of the Geo Flowmeter in a complex hydrogeologic setting consisting of a partially above grade landfill located between a navigable waterway and a large storm water impoundment basin. Mounding effects of the landfill, tidal changes in the channel, varying water levels in the impoundment basin and a complex substrate (alternating layers of sand, silt and clay) presented a challenge for ground water interpretation and analysis. The Geo Flowmeter was lowered into existing monitoring wells surrounding the landfill to determine ground water flow direction and rate. Sensitivity of the meter was sufficient to distinguish two separate flow directions in a single well screen. Later investigation involving installation of piezometers, long‐term ground water level monitoring and plotting of ground water contours verified initial findings of the meter.This article presents numerous graphs and pictures to illustrate field use of the instrument and discusses advantages and disadvantages of its use. Actual field data collected is included to provide a basis for evaluating the accuracy of the instrument and identifying situations where it may be used.