CP-1995-09
Injected helium technology for environmental near-shore water monitoring
Lau, L.S., and A.I. El-Kadi
Use of dissolved helium as a water environment-tracer has been documented by Gupta et al. (Ground Water 32(1), 1994; Hydrological Sciences Journal 93(2), 1994). Helium has many unique attributes that make it attractive for use as a tracer. They include a low background atmospheric concentration, a low molecular diffusion constant in water, a moderate solubility in water, and an easy availability at a low price. This study explored the use of the helium tracer in a shoreline site in Kona, Hawaii. The site is used for ocean thermal energy conversion and for aquacultural operations. Waters are disposed of in a ditch near the shoreline. Continuous monitoring data regarding various chemicals and temperature exist for a number of wells. The specific objectives are (1) to assess the transport processes in a trenchwater-groundwater system and (2) to understand the hydrogeology of the complex system through helium data, extant data, and modeling. Dissolved helium is introduced with return water discharged into a trench, and water is sampled from a monitoring well. The model used allows for density-dependent flow and chemical transport.