VOLATILE ORGANIC COMPOUND PRESENCE IN THE GROUNDWATER BENEATH 'IWO UNSEWERED SUBDMSIONS ON THE CENTRAL WISCONSIN SAND PLAIN By Steven L. Henkel A thesis submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE College of Natural Resources UNIVERSITY OF WISCONSIN Stevens Point, Wisconsin May 9, 1992 APPROVED BY THE GRADUATE COMMITTEE OF: Dr. Byron H. Shaw, Committee Chairman Professor of Soil and Water Science Dr. Ronald F. Hensler Associate Professor of Soil Science Dr. N. Earl Spangenberg Associate Professor of Forestry and Water Science - ii - VOLATILE ORGANIC COMPOUND PRESENCE IN THE GROUNDWATER BENEATH 'IWO UNSEWERED SUBDMSIONS ON THE CENTRAL WISCONSIN SAND PLAIN Steven L. Henkel ABSTRACT The groundwater beneath two unsewered subdivisions in the Central Sand Plain region of Wisconsin was monitored for the presence of volatile organic compounds (VOCs) and other organic and inorganic compounds. The subdivision residents obtain their potable water from the shallow unconfined aquifer, and dispose of their domestic waste via on-site septic systems consisting of septic tanks and drainfields or dry wells. Because of the coarse textured subsoil and shallow aquifer, it was likely that the drainfield effluent was not sufficiently attenuated by the septic system or subsoil environment, and that the groundwater was being adversely impacted by chemicals in the effluent. A residential survey on cleaning product usage was also conducted to indicate areas of possible VOC or other organic compound loading to the groundwater. The product survey results showed a variety of volatile and semivolatile organic compounds were being disposed of by the homeowner's into the septic systems. Single and multiple depth groundwater monitoring wells were installed in the two subdivisions to determine groundwater analyte concentrations. Monitoring wells were also installed on ten homeowner lots both upgradient and downgradient of the septic system drainfields. The monitoring wells were sampled over a seventeen month period from 1987 through 1989. - iii - The average linear velocity of the groundwater flowing beneath the two subdivisions was found to range from 0.5 to 2.2 feet/day. Elevated concentrations of several inorganic compounds such as reactive phosphorous (up to 11.5 mg/Q), nitrites-nitrates (up to 45.8 mg/Q), and conductivity ( over 1000 µmhos/cm) were detected in samples from monitoring wells placed downgradient of the drainfields, and were believed to indicate drainfield plume interception by the well. Samples from many of the groundwater monitoring wells with elevated inorganic compound concentrations also contained detectable concentrations of VOCs, P AHs, and other semivolatile groups of organic compounds. Benzene (2.17 µg/Q to 2.53 µg/Q), toluene (2.1 µg/Q to 5.3 µg/Q), 1,1-dichloroethane (2.4 µg/Q to 8.8 µg/Q), 1,1,1-trichloroethane (5.1 µg/Q to 21.6 µg/Q), and tetrachloroethene (1.9 µg/Q) were detected in groundwater samples from monitoring wells located upgradient and downgradient of septic drainfields. Benzo(ghi)perylene, phenanthrene, fluoranthene, pyrene, and benzo(c )pyrene were detected at concentrations below 1.0 µg/Q in groundwater samples from monitoring wells located downgradient of septic drainfields. Besides septic drainfield effluent, other likely sources of the observed inorganic and organic chemical loading to the groundwater inclu<!e lawn and garden applications of biocides and fertilizers. These inorganic and organic analysis data also indicate that there may be a relationship between the presence of elevated concentrations of inorganic compounds and the presence of potentially toxic concentrations of organic compounds in the groundwater. - iv - ACKNOWLEDGEMENTS I would like to acknowledge the guidance of Dr. Byron Shaw, my major advisor, for seeing me through the thesis process; and the sponsorship of the College of Natural Resources at the University of Wisconsin-Stevens Point. I also thank both Dr. Hensler and Dr. Spangenberg of my thesis review committee for providing many constructive and pertinent comments during the review process. Thanks also goes out to Jeff Andrews for his invaluable assistance in the Trace Organics Lab, for his vast knowledge in the computer field, for his friendship, and for introducing me to Teddy. Good luck in the Sun Belt. Thanks also to Bill DeVito for his help in attempting to keep the analytical equipment operating in the Trace Organics Lab, and for introducing me to NPR. I also wish to thank Eric Harmsen, Pete Arnesen, Mike Heitmann, and other fellow graduate students and personnel of the Environmental Task Force Lab for their help in gathering and analyzing the vast amount of aquifer physical and chemical data, and in helping to install the numerous monitoring wells used to obtain these data.. To my roommate for life, John Krause: Good frields are scarce, good roomates number even fewer, you were both. Your encouragement, your intensity, and most importantly, your distractions were very much appreciated throughout the long years of graduate school. We came out much different people than when we - V - entered. To Sadi and Alex: I am indebted to you both for keeping my feet warm while I tapped on the key board through those long nights and weekends. I owe you. And finally, to my wife Susie who has had to endure long streaches of me not being me, or at least not being me at home; thank you for providing the ultimate incentive to complete this thesis, my son Zachary Steven. - Vl - TABLE OF CONTENTS ABS1'RACT . iii ACKNOWLEDGEMENTS . v LIST OF TABLES . X LIST OF FIGURES . xi I. INTRODUCTION . 1 I.A. INTRODUCTION . 1 LB. OBJECTIVES . 2 II. BACKGROUND . 4 II.A. BACKGROUND INFORMATION . 4 11.B. GENERAL DESCRIPTION OF STUDY AREAS . 6 11.B. l. Jordan Acres . 6 11.B.2. Village Green . 11 11.C. GEOLOGY AND HYDROGEOLOGY OF STUDY AREAS . 16 11.C.l. Geology . 16 11.C.2. Hydrogeology . 18 11.C.2.a. Jordan Acres . 18 11.C.2.b. Village Green . 19 III. LITERATURE REVIEW . 20 III.A. SOURCES OF SYNTHETIC CHEMICALS . 20 111.B. SEPTIC SYSTEM ADDITIVES . 25 111.C. OCCURRENCE AND ATTENUATION OF ORGANIC CHEMICALS IN SEPTIC TANKS . 28 111.D. FATE OF ORGANICS IN THE SOIL AND GROUNDWATER . 32 111.E. GROUNDWATER MONITORING . 33 111.E. l. Monitoring Point Location . 34 111.E.2. Analytical Screening Parameters . 34 111.E.3. Composition of Sampling Materials . 35 111.E.4. Sample Collection Methods . 37 IV. RESEARCH METHODS . 39 IV.A. GROUNDWATER MONITORING PROGRAM .......... 40 - Vll - IV.Al. Site Selection and Initial Sampling . 40 IV.A.2. Residential Product Use Survey . 41 IV.A.3. Water Table Piezometer Installation and Sampling . 43 IV.A.4. Multiport Groundwater Monitoring Well Installation and Sampling . 46 IV.A.5. Groundwater Monitoring Well Installation and Sampling Near Septic Drainfields . 51 IV.B. ENVIRONMENTAL SAMPLE ANALYSIS . 54 IV.B.l. Soil Samples . 55 IV.B.2. Groundwater Samples . 55 V. RESULTS AND DISCUSSION . 57 V.A. RESIDENTIAL WELL SAMPLING . 57 V.B. RESIDENTIAL PRODUCT USE . 58 V.C. WATER TABLE PIEZOMETERS . 61 V.D. MULTIPORT GROUNDWATER MONITORING WELL SAMPLING PROGRAM . 62 V.D.l. November 1987 Sample Event, (Round 1) . 62 V.D.2. January 1988 Sample Event (Round 2) . 65 V.D.3. June 1988 Sample Event (Round 3) . 67 V.E. DRAINFIELD MONITORING WELL SAMPLING AND ANALYSIS . 68 V.E.l. Organic Analytical Results . 70 V.E.l.a. October 1988 Sample Event (Round 1) . 70 V.E.l.b. January 1989 Sampling Event (Round 2) . 71 V.E.l.c. April 1989 Sampling Event (Round 3) . 73 V.E.l.d. Potential Sources of the Detected Organic Compounds . 74 V.E.2. Inorganic vs Organic Analytical Results . 76 V.E.2.a. Jordan Acres . 76 V.E.2.b. Village Green . 77 V.E.3. Drainfield Plume Interception vs. Monitoring Well Position and Product Usage . 81 VI. SUMMARY . 88 VI.A. GEOLOGIC / HYDROGEOLOGIC SETTING . 88 VI.B. RESIDENTIAL WELL voe SAMPLING . 89 VI.C. PRODUCT USAGE SURVRY . 90 VI.D. MULTIPORT MONITORING WELL INSTALLATIONS .... 90 VI.E. DRAINFIELD MONITORING WELL INSTALLATIONS . 91 VLF. ANALYTICAL RESULTS VS. MONITORING WELL LOCATION . 93 - viii - VII. CONCLUSIONS AND RECOMMENDATIONS . 96 VIII. REFERENCES . 101 - IX - LIST OF TABLES Table Description Page# Table 2-1 Subdivision Description Abstract . 7 Table 2-2 Subdivision Description Abstract 12 Table 3-1 Categories of Consumer Products Based Upon Primary Use Within The Home (from Hathaway, 1980) . 21 Table 3-2 Organic Compounds Commonly Found In Household Cleansers (From Hathaway, 1980) . 21 Table 3-3 Organic Compounds Commonly Found in Cosmetics (From Hathaway, 1980) . 22 Table 3-4 Predicted Priority Pollutants in Household Wastewater (From Hathaway, 1980) . 23 Table 3-5 Potentially Toxic Household Wastes of Concern to the WDNR (WDNR, 1983) . 24 Table 3-6 Selected Volatile Constituents in Household Waste Streams Found in Detectable Quantities (From Viraraghavan and Hashem, 1986) . 31 Table 5-1 Frequency of Household Cleaning Product Usage Within Jordan Acres and Village Green Subdivisions ........... : . 59 Table 5-2 Summary of Multiport Well VOC Analysis . 63 Table 5-3 Summary of Organic Parameters Detected During the Septic Study . 69 - X - LIST OF FIGURES Figure Description Page# Figure 2-1 Site Location Map, Jordan Acres Subdivision 8 Figure 2-2 Jordan Acres Subdivision Study Area Base Map 9 Figure 2-3 Jordan Acres Subdivision Residential Drainfield and Private Well Locations Figure 2-4 Site Location Map, Village Green Subdivision 13 Figure 2-5 Village Green Subdivision Study Area Base Map 14 Figure 2-6 Village Green Subdivision Residential