Dutchess County Aquifer Recharge Rates & Sustainable Septic ...

Apr 2, 2006 - of smaller lots to conserve natural greenspace and farmland, as found in “conservation or cluster .... This report work has been completed by The Chazen Companies under funding initiatives by the ...... Phone: (845) 454-3980.
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Groundwater Resource Report

Dutchess County Aquifer Recharge Rates & Sustainable Septic System Density Recommendations Dutchess County Water & Wastewater Authority

April 2006

Prepared for: Dutchess County Water & Wastewater Authority 27 High Street Poughkeepsie, NY 12601

©2006 The Chazen Companies

Groundwater Resource Report

Dutchess County Aquifer Recharge Rates & Sustainable Septic System Density Recommendations Dutchess County Water & Wastewater Authority

April 2006

Prepared by: The Dutchess County Office The Chazen Companies 21 Fox Street Poughkeepsie, New York 12601 (845) 454-3980 Lead Author: Russell B. Urban-Mead, CPG-10328 Senior Hydrogeologist Dutchess County (845) 454-3980

Orange County (845) 567-1133

Capital District (518) 273-0055

North Country (518) 812-0513

Dutchess County Aquifer Recharge Rates and Sustainable Septic System Density Recommendations

Page i

TABLE OF CONTENTS FORWARD EXECUTIVE SUMMARY ............................................................................................. 1 1.0

INTRODUCTION ........................................................................................... 6 1.1

Summary of Aquifer Recharge Rates .................................................. 6

1.2

Summary of Sustainable Septic System Densities ............................. 8

2.0

AQUIFER RECHARGE ANALYSIS ............................................................ 10 2.1

Aquifer Recharge Evaluation Components ....................................... 10 2.1.1

Types of Recharge ........................................................................... 10

2.1.2

Summary of Prior Recharge Rate Estimates ................................. 11

2.1.3

Regional Scale of Recharge Estimates ........................................... 13

2.2

3.0

Dutchess County Aquifer Recharge Assessment .............................. 14 2.2.1

Dutchess County Geology and Aquifers ......................................... 14

2.2.2

Recharge Assessment Method Selection ........................................ 15

2.2.3

Aquifer Recharge Analysis for Dutchess County........................... 18

SUSTAINABLE SEPTIC SYSTEM DENSITY ANALYSIS........................ 21 3.1

Review of Models and Assumptions .................................................. 22

3.2

Septic System Density Analysis for Dutchess County ..................... 25

3.3

Conditions and Applications .............................................................. 26

4.0

RELATED TOPICS FOR FUTURE WORK................................................. 31

5.0

REFERENCES.............................................................................................. 33

The Chazen Companies April 2006

Dutchess County Aquifer Recharge Rates and Sustainable Septic System Density Recommendations

Page ii

LIST OF TABLES Document Tables (bound at rear of report) Table 1: Aquifer Discharge; Baseflow Separation in Dutchess County Watersheds Table 2: Aquifer Recharge Rates; by Watershed/Region & Hydrologic Soil Group Table 3: Recommended Minimum Average Septic System Densities LIST OF FIGURES Executive Figures (bound with Executive Summary) Executive Figure 1: Dutchess County Annual Aquifer Recharge Rates and Minimum Sustainable Septic System Densities Executive Figure 2: Dutchess County Hydrologic Soil Groups Document Figures (bound at rear of report) Figure 1: Dutchess County Watersheds, Precipitation and Geology Figure 2: Detail of Hydrologic Soil Groups versus Surficial Geology Figure 3