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<br />SUbject:
<br />
<br />"Hydrology of a Nuclear-Processing Plant Site, Rocky Flats, Jefferson County,
<br />Colorado," U.S. Geological Survey (USGS) Open-File Report 76-268. March
<br />1976,
<br />
<br />This report contains credible and well-researched information derived from a hydrologic,
<br />geohydrologic, and geologic investigation of the Rocky Flats Plant site, The study was done
<br />for the Atomic Energy Commission to determine how contaminants from an accidental spill
<br />might be distributed as they move through the hydrologic system,
<br />
<br />Information gathering for this report included geologic mapping, test drilling, surface and
<br />borehole geophysical measurements, collection of well data, and installation of three stream
<br />gages, three rain gages, and a stream sediment sampler.
<br />
<br />Limitations
<br />
<br />General
<br />
<br />1.
<br />
<br />Considerable Core Area and Buffer Zone construction has taken place since
<br />the time of this report which would tend to change some of the hydrologic
<br />characteristics of the basins,
<br />
<br />2, The period of record for the rain and stream gages is limited to two years,
<br />
<br />Data Included
<br />
<br />1. Daily rainfall data for three stations at Woman Creek, Walnut Creek, and the
<br />Core Area are provided for the period of April to October from 1972 to 1974,
<br />There are some periods of no record,
<br />
<br />2, Daily stream flow data for Walnut Creek, South Walnut Creek, and Woman
<br />Creek are provided, The period of record of the gages varies, The period of
<br />record is generally mid-1972 to mid-1974,
<br />
<br />3, The runoff from precipitation is approximately 1.4 percent, There was
<br />insufficient data to calculate the percent runoff from rainfall for intense
<br />thunderstorms, The rainfall-runoff relationship for Woman Creek is presented
<br />in Figure 4 of the document,
<br />
<br />4,
<br />
<br />Graphs showing cumulative precipitation for seven different storms are
<br />presented in Plate 3 of the document.
<br />
<br />5,
<br />
<br />The soil infiltration rate is significant. It is quoted from two sources as 0.2-6.0
<br />inches/hour and 3,9-7,35 inches/hour,
<br />
<br />6,
<br />
<br />Drainage basin data, including basin delineation, area, slope, and length are
<br />presented in Plate 2 and Table 1 of the document.
<br />
<br />7,
<br />
<br />Extensive geologic data and interpretations for the plant site are presented,
<br />These data include information on stratigraphy, bedrock formations, surficial
<br />deposits, and geologic structure,
<br />
<br />1.
<br />
<br />This report is particularly useful in understanding the nature of rainfall-runoff
<br />relationships and the interaction of surface water and groundwater, Helpful
<br />illustrations are given,.
<br />
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