Radon-222 in the ground water of Chester County, Pennsylvania

Water-Resources Investigations Report 98-4169
Prepared in cooperation with the Chester County Water Resources Authority and Chester County Health Department
By:

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Abstract

Radon-222 concentrations in ground water in 31 geologic units in Chester County, Pa., were measured in 665 samples collected from 534 wells from 1986 to 1997. Chester County is underlain by schists, gneisses, quartzites, carbonates, sandstones, shales, and other rocks of the Piedmont Physiographic Province. On average, radon concentration was measured in water from one well per 1.4 square miles, throughout the 759 square-mile county, although the distribution of wells was not even areally or among geologic units.

The median concentration of radon-222 in ground water from the 534 wells was 1,400 pCi/L (picocuries per liter). About 89 percent of the wells sampled contained radon-222 at concentrations greater than 300 pCi/L, and about 11 percent of the wells sampled contained radon-222 at concentrations greater than 5,000 pCi/L. The highest concentration measured was 53,000 pCi/L. Of the geologic units sampled, the median radon-222 concentration in ground water was greatest (4,400 pCi/L) in the Peters Creek Schist, the second most areally extensive formation in the county. Significant differences in the radon-222 concentrations in ground water among geologic units were observed. Generally, concentrations in ground water in schists, quartzites, and gneisses were greater than in ground water in anorthosite, carbonates, and ultramafic rocks. The distribution of radon-222 in ground water is related to the distribution of uranium in aquifer materials of the various rock types.

Temporal variability in radon-222 concentrations in ground water does not appear to be greater than about a factor of two for most (75 percent) of wells sampled more than once but was observed to range up to almost a factor of three in water from one well. In water samples from this well, seasonal variations were observed; the maximum concentrations were measured in the fall and the minimum in the spring.

Suggested Citation

Senior, L.A., 1998, Radon-222 in the ground water of Chester County, Pennsylvania: U.S. Geological Survey Water-Resources Investigations Report 1998–4169, 79i p., https://pubs.er.usgs.gov/publication/wri984169.

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Radon-222 in ground water 
  • Hydrogeologic setting and sources of radon-222 in rocks in Chester County
  • Radon-222 in ground water in Chester County.
  • Summary
  • References cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Radon-222 in the ground water of Chester County, Pennsylvania
Series title Water-Resources Investigations Report
Series number 98-4169
DOI 10.3133/wri984169
Year Published 1998
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pennsylvania Water Science Center
Description Report: v, 79 p.; 2 Plates: 38.80 x 28.25 inches and 35.93 x 28.37 inches
Country United States
State Pennsylvania
County Chester County
Online Only (Y/N) N
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
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