A private well off Holsclaw Road south of Gilman Road in Gilroy
has tested positive for perchlorate contamination, leading water
officials to believe the poisonous groundwater plume that has
already tainted 419 wells between Morgan Hill and north Gilroy may
be trickling further south.
A private well off Holsclaw Road south of Gilman Road in Gilroy has tested positive for perchlorate contamination, leading water officials to believe the poisonous groundwater plume that has already tainted 419 wells between Morgan Hill and north Gilroy may be trickling further south.
The Gilroy well owners, whose identity is being kept confidential by valley water, ran a test in May that revealed a 4.7 parts per billion contamination level, less than 1 part per billion above the state’s “action level” which triggers warning notices.
The information was reported to the water district earlier this week, spokesman Mike DiMarco said. It is the southernmost detection of the chemical since testing began in February. A well at Leavesley Road just east of U.S. 101 tested positive at 4 to 10 parts per billion.
“For right now, I’d really consider this part of the plume,” said George Cook, an engineering geologist for the Santa Clara Vallet Water District. “It’s following the general trend of the plume and Olin Corp. is using this information for its new (well) sampling program.”
Cook said Olin’s testing program will likely expand further south now that a detection below Leavesley has occurred.
Olin is the former Morgan Hill flare manufacturer that contaminated the groundwater table with perchlorate from its plant on Tennant at Railroad avenues. It is responsible for testing area wells and devising a clean water program for impacted water users.
The company is only testing wells south of the closed factory site for the chemical used in safety flares, jet fuel and some fertilizers.
Gilroy water officials do not believe the new detection will impact city wells, even though two city wells exist near Holsclaw and Gilman roads. All eight city wells have been tested monthly since February. To date none have shown perchlorate contamination.
