Wisconsin
Soil residual contaminant levels (RCLs)
In Wisconsin, soil results from a cleanup are held against residual contaminant levels (RCLs), the soil cleanup standards set under ch. NR 720, Wis. Adm. Code, part of the NR 700 rule series. The Wisconsin Department of Natural Resources (DNR) describes an RCL as a figure worked out from how toxic a substance is and how much exposure to it is expected. As DNR's page gives s. NR 720.05, a responsible party's soil remedy must bring the soil at least to the RCLs, or to a performance standard set for the site. RCLs are cleanup values developed under NR 720, not a list of sites.
In a Phase I ESA
ASTM E1527-21 does not name cleanup or screening levels among its standard record sources. RCLs matter because they are what a DNR case file measures soil against: whether soil had to be dealt with, what stayed in place at closure, and why a closed property carries duties. Four Wisconsin details shape how to read one.
- Soil above its RCL needs remediation or a cover. DNR says soil over its RCL has to be cleaned up or kept under a cap or barrier, and calls the cover approach a performance standard. Its guidance RR-528 presents performance standards as an alternative to numerical cleanup standards. Where a closed case relied on a cover, read what the closure letter asks of it and look at its condition during the site visit.
- The values come from EPA's calculator and change. DNR's RCL spreadsheet (RR-0151) holds values derived under NR 720 with EPA's Regional Screening Level web calculator, run on the chapter's default target risk criteria, and DNR revises it from time to time. It gives RCLs for two pathways, direct contact and the protection of groundwater, and calculations of cumulative cancer risk from carcinogenic polycyclic aromatic hydrocarbons for industrial and non-industrial land use. Note which version a closure relied on. DNR's Contaminated Soil Quick Reference Table (RR-106), a table of RCLs for common compounds, leaves out the cumulative effects that s. NR 720.12(1) requires, and DNR calls it a quick reference only.
- Industrial numbers bring a use limit. Among the continuing obligations DNR names is keeping industrial use where industrial soil standards were applied at closure, and its example of such a limit is that the owner may have to clean up further if the land changes from industrial to residential or commercial use. Compare the use a closure assumed with the use planned.
- The default number can be replaced. NR 720 lets DNR approve other ways of deciding whether soil needs cleanup. A leaching test can set a groundwater protection RCL for the site. DNR says averaging suits contamination that is widespread, fairly even and close to its RCL, and is not suitable as the only method where hot spots, source areas or far higher concentrations are present. Both need DNR's approval under s. NR 720.07(2)(b). A background concentration can serve as the standard where it is higher than the calculated RCL; the spreadsheet lists DNR's background threshold values for several inorganics, and for a substance without an assigned value a background figure is set for the site by a method DNR approves (s. NR 720.07(3)).
Soil is one medium. Groundwater standards sit in ch. NR 140, Wis. Adm. Code, and DNR says most of them, though not all, match the federal drinking water standards. DNR counts contamination in the smear zone, between the historic high and low water table, as soil contamination even where it is at times saturated.
How a site closes
When the investigation and cleanup are finished, the responsible party may send DNR's regional office a case closure request (Form 4400-202) under ch. NR 726, and gets a case closure letter if the closure criteria are met. In DNR's tracking database a closed activity is one whose cleanup requirements are all done and for which that letter has issued. Where contamination above state standards stays behind, DNR writes continuing obligations into the closure letter; they pass to each later owner, and DNR enters the property in its online database. DNR's RR Sites Map does not show soil left above RCLs at cleanups completed before August 1, 2002, so for an older closure read the letter itself. See Continuing obligations and residual contamination.
Where to read the rule and the numbers
DNR's Contaminated soil and sediment page links its Soil Cleanup Standards Guidance (RR-0152), the RCL spreadsheet, the quick reference table, guidance on background levels, averaging and leaching tests, and ch. NR 720 on the Legislature's site. This handbook did not open the guidance or the spreadsheet and carries no values from them. The page names a Remediation and Redevelopment (RR) Program contact for questions on RCLs; the program's staff are on the RR Program staff contacts page.
Where to look a site up
DNR's RR Sites Map has a layer called Continuing Obligations Apply, and its identify tool links a site to BRRTS on the Web, where DNR says the documents may include the closure letter, property maps and contaminant data. See RR Sites Map and Bureau for Remediation and Redevelopment Tracking System (BRRTS).
Getting the file
DNR files records by program rather than by facility, so it asks a requester to name the kinds of records wanted. For a closed cleanup, ask for the case closure request, the closure letter and the soil data behind it. DNR prefers records requests by email, to DNRRecordsResponse@wisconsin.gov, and accepts them in any format; see Public Records Request.
Sources
Wisconsin Department of Natural Resources pages, read October 17, 2026, no modified date shown:
Wisconsin Department of Natural Resources pages, read October 13, 2026, no modified date shown: