Laserfiche WebLink
The table below indicates the NL and RL for each of the four PFAS chemicals as <br /> established by DDW: <br /> DDW Advisory Levels for PFAS n /L <br /> PFAS Notification Level Response Level <br /> Perfluorooctanesulfonic acid PFOS 6.5 40 <br /> Perfluorooctanoic acid PFOA 5.1 10 <br /> Perfluorobutanesulfonic acid PFBS 500 5000 <br /> Perfluorohexanesulfonic acid PFHxS 3 20 <br /> Per the Order, the City tested and received the results on March 8, 2023, as <br /> summarized in the table below. <br /> 2023 Quarter 1 PFAS Test Result Summa n /L <br /> PFAS Wells Well Well <br /> Perfluorooctanesulfonic acid PFOS 12 18 23 <br /> Perfluorooctanoic acid PFOA 2.2 2.4 2.4 <br /> Perfluorobutanesulfonic acid PFBS 3.6 4.2 5.1 <br /> Perfluorohexanesulfonic acid PFHxS 12 16 20 <br /> The first quarter tests show that all three City-owned wells exceed the NL established <br /> by the DDW for PFOS and PFHxS, and that Well 8 equals the RL established by the <br /> DDW for PFHxS. Based on these test results, Well 8 remains out of service (was placed <br /> in "Standby" with DDW in June 2019 for being above the RL for PFOS at that time of <br /> issuance and has not operated since) while Wells 5 and 6 could remain in service. <br /> As a water provider, Zone 7 similarly is required to conduct quarterly testing on its water <br /> sources. Zone 7's surface water supply at both treatment plants were `non-detect' when <br /> tested for the PFAS constituents. For Zone 7's groundwater supply, the Stoneridge well <br /> and Chain of Lakes 1 and 2 wells have not operated since fall/winter 2022 and are <br /> currently under construction to add PFAS treatment systems. Zone 7's Mocho 2 and 3 <br /> wells are currently being treated at the Mocho Groundwater Demineralization Plant and <br /> blended with Mocho 4 well water to ensure the water is below the RL (but not the NL) <br /> before being supplied to the City. The agency's Hopyard wells were `non-detect' when <br /> tested for the PFAS constituents. As Zone 7 operates a connected treatment and <br /> distribution network, the water provided by Zone 7 to any of its water retailers may come <br /> from any of these sources. <br /> DISCUSSION <br /> Recommended Approach <br /> Having received the results of the first quarter testing, staff is presenting a <br /> recommended approach as a reasonable near-term option for the City Council's <br /> consideration: <br /> Page 3 of <br />