BWD to Consider Well Abandonment

 

Last updated 5/24/2024 at 1:10pm



The Borrego Water District Board will be discussing potential abandonment of one of its wells due to degrading water quality. Well ID1-8 is located in the south/western end of Borrego Springs, off Borrego Springs Road past La Casa and has been a potable source of drinking water supply to the community since 1972 pumping water from 72 to 830 feet below ground surface (bgs).

Elevated arsenic concentrations were first detected in Well ID1-8 in 1988 during a period of higher production from the well and prior to the adoption of the lower drinking water standard for arsenic in 2006. Annual production decreased from 1992 to 2016 and the arsenic concentrations in Well ID1-8 decreased to stabilize below the drinking water standard.

With the resumption of greater pumping from wells in the SMA in 2016, the arsenic concentration in Well ID1-8 increased and is now consistently detected near the drinking water standard. Considering the elevated concentration of arsenic detected in Well ID1-8, the Borrego Water District staff has elected to take the well offline and has informed the Division of Drinking Water (DDW) that Well ID1-8 is no longer in service.


Well ID1-8 is now 52 years old and is near its remaining useful life estimated at 60 years as a production well. BWD staff communicated that a recent down-well video log of the Well ID1-8 revealed a hole in the well casing and that gravel pack has entered the well. A monitoring well, MW-3, is located approximately 120 feet north (heading of 13.16 degrees) from Well ID1-8 and is completed to a depth of 325 feet bgs with screen from 175 to 325 feet bgs. MW-3 is classified a Representative Monitoring Well (RMW) for purposes of reporting groundwater levels and compliance with the Sustainable Groundwater Management Act. A comparison of groundwater levels from Well ID1-8 and MW-3 indicates similar static groundwater levels.

Because Well ID1-8 has reached near its remaining useful life and a recent video inspection of the well revealed a hole in the well casing, BWD staff and its Consulting Engineers INTERA (Trey Driscoll) will be recommending to the Board that the well be properly abandoned.

INTERA recommends continued monitoring for groundwater levels. Depth-discrete water quality sampling could be performed to better characterize variable water quality by depth over the interval from 72 to 830 feet bgs. Additional wellhead water quality sampling is not recommended. Alternatively, Well ID1-8 could be considered for conversion to a non-potable irrigation well; however, the cost on the conversion may be of limited benefit since the well is near the end of its remaining useful life.

Well 8 is in the S/E corner of the Borrego Springs and geographically isolated from the remainder of the Basin. Water Quality is monitored semi annually at all BWD wells as well as dozens of private wells in the Basin for continuous data collection and periodic analysis. To date, there is no indication of arsenic contamination risk in any other BWD, or our neighbors.

 
 
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