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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00239 | ||
| PWS Name: | LONDON WATER CO-OP | ||
| Who Was Contacted: | Terri Finn-Kadrmas | ||
| Contact Phone: | 541-942-8563 | ||
| Contact Date: | 02/04/2021 | ||
| Contacted By: | CIVIL WEST ENGINEERS, INC (DWP) | ||
| Contact Method/Location: | Field | ||
| Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
| Details: | Background/Problem Identification: LWC is in the process of switching their water system from surface to ground water. LWC has two wells which they intend to use as groundwater sources. LWC wants to begin with the one with the lesser flow to perform a pilot test on arsenic removal with “MetSorb” product to determine arsenic removal efficacy of the “MetSorb” on their groundwater. Assistance Provided: The circuit rider reached out to Terri Finn-Kadrmas and scheduled a site visit on 02/12/2021. The circuit rider met with Dennis and Terri, and several other of the LWC members. Dennis showed the recently acquired backwashable media filters that he intended to use for the pilot study. Dennis has also purchased an iron filter to run upstream of the proposed arsenic filters to allow the arsenic filters to mitigate shorter filter runs that would likely occur if the MetSorb was tasked with removing both arsenic and iron. The circuit rider was told that the historic levels of arsenic in the groundwater are approximately 300 ppb (0.300 ppm, 0.3 mg/L), which is roughly 30 times greater than the MCL of 10 ppb (0.010 ppm, 0.010 mg/L). According to this estimate and the information available on the arsenic adsorbent website, https://www.gravertech.com/product-lines/adsorbents/metsorb/heavy-metal-removal-granules/ , we can expect approximately 0.3 mg/L * 7,500 gpd * 3.785 L/gallon = 8,500 mg or 8.5 grams of arsenic will need to be adsorbed per day. The same website indicates that, “MetSorb® HMRG media’s adsorptive capacity is 7-12 grams of arsenic per kilogram of HMRG adsorbent in drinking water applications with a pH range of 6.5-8.5”. At this rate we can expect to use approximately a kilogram of MetSorb per day to treat 7,500 gpd. Dennis had a 1.5 cubic foot box of the MetSorb product on site. Based on the density of 40 lb/ft3 on the Gravertech website, this box is estimated to treat 7,500 gallons per day for 27 days. LWC intends to run the pilot test continuously |
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