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WATER GREMLIN FU'BLI•C .HEALTH ASSESSMENT-. I*UBLIC C.OK4MENT DRAFT <br />Air •Monitbringfor t-DCE - Data from• March 2019 to March 2021 <br />The 2019 settlement agreement required Water Gremlin to conduct ambient airmonitoring.•F.ive-air <br />monitors were placed on.:the.Water Gremlin property near the property boundaries (see Figure 4 <br />below). Beginning on March 1, 2019, 24-hour samples were collected by Pace Analytical, an <br />independent enytronmental laboratory, every three days;.and analyzed••for a standard list of VOCs. Lab <br />results are reported directly to the: MPCA. Monitoring results have been highly variable; reflecting <br />voriation-in.weathee (mainly wind,speed and -direction) and the.rate of t-DCE use at the facility. <br />Figure 4: 4ocodons of Air Monitors around the Water. •Grerrfliii Fdcliity <br />Note, The blue circles indicate wrrent. V.00 monitors, the graydreles are.the former lead monitor locations.. <br />During the period from March 1 to August 22, 2019 when Fiuo$oly was used, t-DCE resuIts. ranged from <br />not detected (shown by a :symbol: and a number which is the lowest level detectable) to 648 µg/MS as <br />summarized in Table 2 below. <br />Tdble 2: t-DCFAi'r Monitoring Results on Water Gremlin Property from 311119 to 8122119 (Pg/m3J <br />' 1 � F�{'S; •;.v::'��� kStivi'� <br />�. y... -.. r-�'-.-Y�+�+�s-��' <br />-;il�o "itiar ocal�pn; <br />'t• -c-u -,�'- t ..,?� <br />-�{Y�tf`•'�•'-^r�2asi�� '.ti•;r.���'x�LSfyvi'� .t�•,v:'�:u�ti <br />"'�.:.. `,g!.�:«frFa:' nk�y-(v-i'i.�s"-'x <br />��•stt <br />Yc �'••- :'fy(�cr'�s"-3,�„�-i cy-,,:�F.-,-�-r <br />";i°� .9'C'.�.^. <br />.�5,.-'r., t,;� k. ti.�..? . •:. `R nk'.•h'._"s" <br />-"ter^�ri k�`, .-'x� '` <br />-•� ���'� - 7. �;�'.��.-:•L:, =✓y�i:,rc;. <br />East <br />¢1.1 <br />205 <br />11 <br />1 29 <br />North <br />�Northwest <br /><1 <br />208 <br />.5 <br />33 <br />349 <br />5 <br />21^ <br />South <br />---- West. ~_._. _ <br />-cl.1 <br />�1:1 ._.. <br />104 <br />_..._.. 648 <br />- <br />4 <br />__.__._ <br />2-1 <br />15 <br />.._._...._ 86.-•-•----- <br />* A median is the middle value of the results (approximately half the results are less than and half the results are greater than <br />the. median). Whip the:monitors did.not detect any:t-DCE, MDH used the detection limit (rather than zero) when calculating <br />the medlarrarid •averagi:•resulo.••This results•irrmedian and average •values that are biased high (overestimations). <br />Air`Mcinitoring•at the five -monitors on the Water Gremlin property continued duririg.the time the <br />coating.iines were shut down. Daring the shutdown period, low levels oft-DCE ranging from 1.2 to 5.6 <br />µg/m3 were detected In•brily 16.samples out of 237 total individual.samples from 48 sampling days. <br />Use of t-DCE resurood on-January'21,2020 at lower quantities than in 2019. Air monitoring results <br />reflect tliis decilhe in use of t-WE that -started in 2020 (see Table 3. below). <br />17 <br />