This report presents borehole geophysical logs from 21 wells completed in bedrock near the village of Windham, N.Y. The data were collected as part of a water-resources investigation conducted by the U.S. Geological Survey, during 1990-93, in cooperation with the New York City Department of Environmental Protection. Natural gamma logs, caliper logs, and fluid-conductivity and temperature logs are depicted for each well; driller's logs are included where available. Location maps and a table of selected well data are included. The geophysical logs provide indications of rock type and occurrence of water-bearing fractures.
Deep observation boreholes in the vicinity of active production wells in Honolulu, Hawaii, exhibit the anomalous condition that fluid-column electrical conductivity logs and apparent profiles of pore-water electrical conductivity derived from induction conductivity logs are nearly identical if a formation factor of 12.5 is assumed. This condition is documented in three boreholes where fluid-column logs clearly indicate the presence of strong borehole flow induced by withdrawal from partially penetrating water-supply wells. This result appears to contradict the basic principles of conductivity-log interpretation. Flow conditions in one of these boreholes was investigated in detail by obtaining flow profiles under two water production conditions using the electromagnetic flowmeter. The flow-log interpretation demonstrates that the fluid-column log resembles the induction log because the amount of inflow to the borehole increases systematically upward through the transition zone between deeper salt water and shallower fresh water. This condition allows the properties of the fluid column to approximate the properties of water entering the borehole as soon as the upflow stream encounters that producing zone. Because this condition occurs in all three boreholes investigated, the similarity of induction and fluid-column logs is probably not a coincidence, and may relate to aquifer response under the influence of pumping from production wells.
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