Section Eighteen
LAND DISPOSAL
76    WISCONSIN GROUNDWATER QUALITY STANDARDS: CAN
WASTEWATER LAND TREATMENT SYSTEMS MEET
THEM?
David K. Sauer, Environmental Engineer
Stephen Scott, Environmental Engineer
Division of Environmental Standards
Wisconsin Department of Natural Resources
Madison, Wisconsin 53707
INTRODUCTION
The Wisconsin Legislature enacted a comprehensive state groundwater protection law (Wisconsin
Act 410) in 1984. Chapter 160 of this law directed the Wisconsin Department of Natural Resources
(WDNR) to establish numerical groundwater standards. The resulting rule, Chapter NR140, Groundwater Quality, was developed by the WDNR and became effective October 1, 1985.' The rule applies
to all facilities, practices, and activities which may affect groundwater quality and which are regulated
by a state agency. The rule specifically requires the WDNR to evaluate and determine if wastewater
land treatment systems are meeting numerical standards at specific groundwater locations.
Wastewater land treatment systems in Wisconsin are used largely by the food product industries
which discharge to many different types of systems and by municipalities which most often discharge
to absorption ponds.2 The wastewater contains biochemically degradable material having substantial
carbon and nitrogen content and generally very low levels of toxic substances.
These systems are currently regulated through the use of wastewater discharge permits and treatment plant plan approvals issued by the WDNR. The plans are reviewed for compliance with the
design criteria contained in Wisconsin Administrative Codes NR214 and NR206. Both of these design
codes, however, were promulgated prior to October 1, 1985, the effective date of the groundwater
quality rule, NR140.
If a strict interpretation of NR140 is taken, a significant number of wastewater land treatment
systems will exceed one or more of the numerical standards in the rule. This paper will explain why
this is occurring and what the WDNR is doing to resolve the problem. First of all, several hydrological
monitoring and modeling studies are being conducted with the University of Wisconsin-Madison. In
addition, experience with the application of NR140 standards to existing sites has occurred since
October, 1985.
WISCONSIN ADMINISTRATIVE CODE, NR140. GROUNDWATER QUALITY
Each groundwater quality parameter listed in NR140 is placed in one of three categories. The three
categories are health-related parameters, Welfare-related parameters, and indicator parameters. A
partial listing of parameters from each category most frequently monitored at wastewater land
treatment systems are listed in Tables I, II, and III. Applicable enforcement standards and preventive
action limits (PALS) for each parameter are also listed.The enforcement standards are the primary
and secondary drinking water standards for those parameters as specified by the Environmental
Protection Agency and the National Academy of Sciences. Enforcement standards apply only at or
beyond a facility's property boundary or at any point within the property boundary which is beyond
the three dimensional design management zone (DMZ). The DMZ for wastewater land treatment
systems extends horizontally 250 feet beyond the waste boundary for those systems designed to seep
and 100 feet for those systems designed not to seep.
The preventive action limit (PAL) is always less than the enforcement standard. For health related
parameters, the PAL is either ten percent or twenty percent of the applicable enforcement standard
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