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WATER GREMLIN PUBLIC HEALTH ASSESSMENT: PUBLIC COMMENT DRAFT In March. 2021, Water Gremlin submitted a proposed workplan that includes dredgiing the eastern stormwater.pond to rem ove.lead-impacted sediment and red uce..additiopal lead that.could ultimately affect. Lambert Creek.(Stantec, 2021). This work has not been completed as. of April 2022. Water.Gremlin operations have contributed to lead concentrations.! n sediments; particularly in samples nearest the facility to the east and southeast. There is expected to be little to no trespassing that would result in human exposure to the lead in these sediments. F. Surface Water As mentioned above, the Water. Gremlin. property contaIns.a portion of Lambert .Creek, three stormwater retention ponds, and wetlands. The east and.west retention ponds flow.into Lambert Creek.. SaMpies from these surface waters were tested for VOCs, lead, and 1,4=dioxane, Figure.10 shows the locations of the lead samples. In June 201% six surface water samples were collected from Lambert Creek and analyzed for VOCs and lead (Wenck, 2D19). No VOCs were .detected, but lead was found in three samples (up to.12.5 ppb); two of the samples exceeded..MPCA's Tier I. Surface Water Screening Criteria (SW Criteria) of 6.7 ppb. Accordingto the MPCA Surface. Water Pathway Evaluation User's Guide (MPCA, 2006) Tier 1 surface water risk. evaluation "...requires. the least level.of effort and the most conservative standards, guidelines and criteria. It is used to screen.out sites that are not of concern." If the:Tier,1 investigation identifies contaminants at levels above those standards, guidelines or criteria, additional investigation may be required depending on the magnitude and extent of the contamination. MPCA staff conducted surface water sampiing.for lead testing in water bodies located in the.communify and well outside Water Gremlin property bouridaries in September 2019. Lead was detected, but below Tier I.Stand.ards in Birch Lake; Columbia Park Pond, Goose Lake, Lambert Creek, and Rice Lake. Lead was not detected in White Bear Lake. In Octo4er2019, 14 additional surface water samples were collected and analyzed for lead .on the Water Gremlin property (Wenck, 2020). Eight samples were. fro m the.north bank of Lambert Creek;.six were from .tributaries to and wetlands that drain into Lambert Creek or discharge`from stormwater ponds. lead was detected. 1n every sample. Ten samples were below SW Criteria, ranging from 0.12 -1 ppb, and four exceeded the. criteria. Three of the samples that exceeded SW criteria -were collected from the stormwater discharge from the Water Gremlin facility, and lead ranged in concentration from 26.4 - 88.1 ppb. The fourth sample that. .was.above the SW 'Criteria, at 640 ppb, is. the easternmost (upstream) sample on the property and.was collected from a southern inlet to Lambert Creek, However, this. sample may not have been filtered to remove suspended. sediment, which is standard practice for surface water samples. Suspended sediments in wetland samples ca.n increase measured concentrations of metals, which.may account. for the very high.level of lead observed in this sample. The other,sample collected from this tributary, at a location downstream less: than 250 feet away, had only 0.68 ppb lead, which.casts. further doubt on the results for the potentially unfiltered sample collected from this location. M..PCA req u ested. testing for lead from the Water Gremlin facility roof stormwater runoff, to see if the runoff was a.sou rce'of lead contamination in the east .stormwater pond. Two downspout samples were. ca..]lected-du ring..a rain event in October 20i9.. The two results were 1.6 and 2.7 ppb lead.:Whiie these results show that small amounts of Iead.are coming off the:facility roof, they are expected amounts and illustrate the purpose.of a.stormwater collection system. 32