Before I dive into the ‘dirty details’ of environmental soils data in Phase II Environmental Site Assessments, let me first explain Metadata. Metadata, or data about data, is used to describe the thought process and meaning behind raw information. Simply, it is often nothing more than explanatory text. For example, a database may hold a set of coordinates for a point on the earth’s surface. Maybe the point represents the location of your favorite downtown restaurant. The metadata text will tell you how the coordinate data was collected, in what geographic coordinate system, and by whom. (Unfortunately though, it probably won’t tell you that the service is terrible on Friday nights and that they pour the cheap stuff in your top-shelf martini – you’re on your own there.)
Environmental data in Phase II ESAs
And in the environmental realm, we collect lots of data. Dissolved oxygen concentrations in a fly fishing stream. Site Characterization soil gas data from a contaminated property. The number of endangered Hawaiian hoary bats hanging in Honolulu. The environmental data set is vast.
However, of particular interest to those in the real estate sector is soil analytical data collected during Phase II ESAs. Here’s a typical scenario: a developer wants to convert an old abandoned structure with broken windows and graffiti stained bricks into a mixed-use building with swanky retail spaces, modern offices, and affordable housing. Everybody in town, from Mayor McCheese to Ronald McDonald, thinks it’s a great idea. The building will go back on the tax rolls, surrounding property values will increase, and that shady Hamburglar will stop hanging out behind the building. Win-win-win.
An initial Phase I Environmental Site Assessment identifies potential contamination at a property, so soil sampling is performed to evaluate the issue. Oh-oh. The results of the subsurface tests confirm Ethyl methyl death at a concentration of 612 part per million (ppm) in the soils… everywhere. No big deal? Run for the hills? Something in between requiring consultant and attorney invoices? This data means little without a good dose of metadata to help us make sense of the situation.
Analyzing the data of the Phase II ESA
As an initial sniff test, the environmental consultant will compare the soil numbers to published screening criteria. These benchmarks are quantified by federal entities like the EPA and state agencies such as California’s Office of Environmental Health Hazard Assessment (OEHHA) or the Kansas Department of Health and Environment (KDHE) and go by ominous names including Soil Cleanup Objectives, Soil Cleanup Criteria, and Soil Remediation Standards, among others. These soil screening standards may not be the end all, be all, but they offer an excellent starting point.
Beyond the multitude of names for the comparison criteria, there are typically several soil numbers for any given compound. And that makes sense because there are differing means that a chemical can cause harm. For example, when contacting skin the chemical may cause acute dermal exfoliation (aka walking skeleton syndrome); It may emit vapors that can cause irreversible symptoms of death. It may readily leach from the soil and enter drinking water supplies, where it masks itself by tasting like cheery Kool-Aid. Adding yet another layer, the criteria can be further evaluated based on property use. We make different assumptions of exposure and risk depending on whether the building will be inhabited by happy families, as opposed to working stiffs. As you could probably guess, the allowable limits for chemicals of concern are lower for residential scenarios.
So let’s circle back to our example – ethyl methyl death in soils at the redevelopment site. The maximum concentration was 612 ppm, just outside the back door where janitor Fred used to dump industrial waste on rainy days (the drum storage area was way in the back, and he absolutely hated getting his hair wet). The good folks at the relevant oversight agency – let’s call it the Interstate Diagnostic Institute of Toxicology in Soil (IDIOTS) – developed the following compound-specific soil criteria:
- Residential direct contact (the upper safe contact limit for residential uses): 500 ppm
- Nonresidential direct contact (the upper safe contact limit for industrial/commercial uses): 750 ppm
- Vapor intrusion (the concentration where the chemical is expected to volatilize and become an air issue): 600 ppm
- Impact to groundwater (the concentration where the chemical is expected to leach to groundwater): 25 ppm
So, looking at the numbers, IDIOTS would have us know:
- As the residential direct contact criteria was exceeded, if this redevelopment is going to include a residential component, we are going to have to either remediate (or maybe install a cap to keep the kiddies from making ethyl methyl death mud pies!).
- If the site use is limited to commercial or industrial uses, because we did not exceed the nonresidential direct contact criteria, we wouldn’t have to complete active remediation to address the soil physical contact issue. However, a notice would have to be placed on the deed to warn future buyers of the non-residential use restriction.
- It’s a close one on the vapor intrusion issue, as the concentration barely exceeds the criteria. However, looks like additional investigation will be necessary in the form of potential soil vapor and indoor air sampling.
- Judging from the comparatively low impact to groundwater criteria, ethyl methyl death is highly mobile in soils and can readily dissolve in groundwater. So, at this site we would drill monitoring wells to collect groundwater samples.
Metadata: the importance of context
Often, when environmental data is presented, it can benefit from metadata in the form of explanatory text. To avoid the issue of garbage in, garbage out, we certainly want metadata describing how the data was collected.
But, more importantly we’ll want metadata in the context of data evaluation. In plain language, we need to know what to make of the raw numbers. Specifically regarding soil analytical data, during the Phase II and Site Characterization, we’ll first look to published regulatory comparison standards in the deciphering process. Then, with an ever-focused eye on the client’s needs in part driven by the property end-use, an experienced consultant will be able to convert the cryptic numbers into valuable information and advice that will allow the client to achieve regulatory compliance and make informed business decisions.