Map of Ground Water Monitoring Well Locations: 2009
This map of the locations and designation numbers for ground water monitoring wells at the UNOCAL Edmonds site was prepared by ARCADIS and is shown here with their permission. It provides a handy reference for identifying the locations of monitoring wells mentioned in blog postings. To enlarge the map so that details, including well numbers, can be easily seen, use the magnification tool and scroll around on the map.
Of the 49 monitoring wells shown on the map, 9 are no longer being sampled for ground water chemistry analyses. Those 9 wells are: 203 and 134-X in the eastern portion of the site; 13U, 122, E, and 131 in the central portion of the site; 126 and 151 in the western portion of the site; and 301 to the west of the site, across the railroad tracks.
The remaining 40 wells are being sampled every other month and include two sets of wells. A “perimeter” set of 21 wells is being sampled for compliance with cleanup levels (from southwest to southeast along the site perimeter, those wells are: 150, 149R, 524, 147, 523, 8R, 522, 20R, 104, 101, 518, 139R, 510, LM2, 108, 109, 129R, 501, 500, 135, and 136). An “interior” set of 22 wells is being sampled to evaluate the improvement in ground water quality (i.e., natural attenuation) after the Interim Action cleanup activities. These Monitored Natural Attenuation (MNA) wells include three sets of 7 wells each along three ground water flowpaths (shown as elongated enclosed areas on the map), plus one additional well at a location where product (LNAPL) was present at the start of the recent Interim Actions. The flowpath wells are: East – 502, 503, 504, 505, 506, 507, and 508; Middle – 511, 512, 513, 514, 515, 516, and 517; and West – 143, 519, 520, 521, 522, 8R, and 523. The additional well, in the north central portion of the site near Detention Basin 1, is 509. Note that the three most downgradient wells in the West MNA system are near the property boundary and are therefore included in both the Compliance and MNA well systems.
The complicated numbering system for current monitoring wells results from the completion of wells at various times over the long history of site investigations and the retention of wells from earlier investigations within the post-Interim Action ground water monitoring program. Many early wells have been removed in the course of various cleanup activities at the site. This map will help readers follow events as the two-year ground water monitoring program unfolds through 2010.
Enlarge this figure by double-clicking.
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