Agenda - 09-21-1999 - 2 - Laserfiche WebLink

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SEP -27 -1999 •14 24 JOYCE ENGINEERING, INC. Sicte of North Carolina Department of Environment, Health and Natural Resources Division of Environmentol Management James S. Hunt, Jr., Governor Jonathan B. Howes, Secretory A. Preston Howard, Jr., P.E.. Director 1 336 323 0093 P.02iO4 C.�EHNF41 GROUMWATFR SECTION October 6. 1995 Environmental Service Companies and Consubtats Subject: Changes in Technical-Policy Concerning Slug Tests This is to notify you of specific corrections and revisions that were made to the slug t St Policy statement that was issued on Am 30, 1994. The June 30; 1994 statement indicated that she Division of Environmental Management (DEK would only reimburse for slug tests per ormea iti monitoring wells that were constructed withthe calk* length of well screen and sand pack within The saturated zone. Based on further evaluation of the published scientific literature, the DEM has amended its policy to allow for retmbum mart of slug tests-performed in mordtori.ng wells that :ire screened across the water table, provided that these tests are implemented and analyzed in accordance with the peer- reviewed, published test method utilized. Bouwer and Rice (1976 and 2989) and Hvorslev (1951) are the most common test niedicds used for partially penetrating wells in unconfined aquifers These mediods may be used fur both "slug -in" tests .(falling head tests) and "slug -out" tests (rising head, recovery or bait tests) . in monitoring wells where the well screen .and sand pack are entirely below the water table. For monitoring wells screened across the water table, these methods may only be used for slug -out tests. Slug -in tests are not appropriate, since part of the water added, would flow out of the well into the vadose zone resulting in an overestimation of the hydraulic conductivity. Furthennore, it should be noted that only the length ofwell screen located in the saturated zone should be used ro: ralculatc hydraulic conductivity. Using the total screen length would result in under estimating tlds ;gar 3:r. t r The June 30, 1994 policy statement also indicdFd that hydraulic conductivity value btained thorn slug tests would not be allowable for use in groundwater models. However, Since slug Cests sera generally considered an appropriate means of estimating the ordcr of inagnitudc of hydraulic conductivity, the DEM has revised its .policy to allow for the use of slug test data tc model groundwater flow at locations where there are no potentially impacted receptors that pose a risk ro lurman health and the enviroriment'and.where corrective action under NCAC 15.E 2L.0106 (k).(1)' q; (in) is proposed. Pumping tests will still be required for locations where it is necessary .o o timin the most accurate hydrogeologic data possible (e.g., there are potentially impacted receptors that may P= a risk to human health or the environment, or for designing groundwater remediation systcn:s that involve the withdrawal of groundwater). P.O. Sox 29635. RGielgh. North Caroino 276260SX Telephone 919- 733 -7015 FAX 914- 733 -2496 An Fgvd opp*OUM VA*matkm Action FrmMoyor 6D% recycled/ 10%x- conwTier popor