Sampling groundwater from exploratory boreholes can be a challenge due to their depth, remote locations, and purging needs – that is, drilling fluid used during the drilling of the borehole creates a water column that needs to be purged prior to sampling in order to attain a representative sample. In deep boreholes, this can mean that hundreds or thousands of gallons of water needs to be removed prior to collecting a sample.
BESST’s zone isolation technology minimizes the volume of standing water that must be purged prior to sampling. We offer custom solutions to sample from boreholes as deep as 3000 Ft. below ground surface.
In 2016, BESST designed a Pump-to-Packer integrated system to sample from 3-In. boreholes in the San Gabriel Mountains in California. The system utilized both hydraulic and pneumatic packers to isolate 20-Ft. zones in vertical and angled boreholes up to 2400 Ft. deep, eliminating as many as 800 gallons of wastewater. Once the pump and packer assembly was installed in a borehole, that same pump could be used for both purging and sampling, saving even more time.
BESST sampled a 1,912-foot-deep monitoring well in the Mojave Desert in Southern California. The standard procedure of purging three casing volumes before sampling would have required 936 gallons to be pumped out of the well prior to collecting a sample. Our geoscientists assessed the well construction and surrounding lithology and were able to minimize the pumping volume by installing a temporary packer system with a custom connection to a slim-fit Panacea P125 pump. As a result, only a small fraction of the well had to be purged, saving more than 900 gallons of wastewater and many days of field time.