{"id":384,"date":"2009-10-03T10:55:26","date_gmt":"2009-10-03T14:55:26","guid":{"rendered":"http:\/\/sootypaws.net\/blog\/?p=384"},"modified":"2022-04-15T10:57:21","modified_gmt":"2022-04-15T14:57:21","slug":"risk-assessment-part-one","status":"publish","type":"post","link":"http:\/\/sootypaws.net\/blog\/2009\/10\/risk-assessment-part-one\/","title":{"rendered":"Risk Assessment, Part One"},"content":{"rendered":"\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nThis\nis a follow-up post to The Numbers<\/a> where we provided laboratory analysis results\nfor a sample of pit waste at a natural gas well site. Risk assessment is a huge\ntopic so we’ll be splitting the post into two parts. In this part we’ll discuss\nsome features of the site that have to be taken into consideration and use\ninformation on a\ntable we’ve created<\/a>\nwith various screening levels and other information for the chemicals analyzed\nby the laboratory in the sample.

\nWe’re not doing a full assessment of the site; what we’re doing is trying to\nfind is out if a full assessment toward remediation is necessary.

\nThe state’s DEP Office of Environmental Remediation has several publications\nthat have been helpful to us. These are all associated with their program of\nvoluntary remediation. A\nPlain Language Guide to Human Health Risk Assessment<\/em><\/a> is a description of the process of analysis and\ndecision-making. There is a helpful checklist at the end which is taken from\nAppendix A of West\nVirginia Voluntary Remediation and Redevelopment Act Guidance Manual<\/em><\/a> which is a much more technical document written\nfor remediation specialists. The third element in the publication mix is the De\nMinimis tables<\/a>\nwhich are part of 60 Code of State Regulations 3. These tables provide\nscreening levels for a large number of chemicals. (The state’s and EPA’s tables\nuse exponents such as E-01 or E+02 with concentration, e.g., 3.89E-01. E-01 is\nequal to X 10-1<\/sup> and E+02 is equal to X 102<\/sup>. For the\nexample 3.89E-01, the concentration is then 0.389. We find this method of\npresentation to be a pain and much prefer either a uniform parts per billion\npresentation or as we’ve presented the figures in our table. A scientific\ncalculator will easily convert positive and negative exponents.)

\nWhen we had analysis done we just asked for metals, chloride and radium 226 and\nradium 228. Chloride doesn’t have a screening level, in spite of the fact that\nthere is a secondary Maximum Contaminant Level for drinking water for chloride\nand in spite of the fact that chloride can be toxic to aquatic life, birds and\nmammals. Radiological screening levels are a whole other topic and since the\nradium in the sample was at an acceptable concentration we’ve put that aside.

\nThree of the metals that we had analyzed, even though they show high\nconcentrations, are not considered important in an environmental assessment —\ncalcium, magnesium and sodium. In the end, the assessment has to focus on\narsenic, barium, chromium and lead (cadmium was not able to be detected by the\nlaboratory), though we believe the high chloride is an important factor.

\nThe site is a gas well drilled in 2005 to the Marcellus formation but two other\nshales were also fractured. Copies of the well\ncompletion report<\/a>\nand plat<\/a> are available for download. The well has a pad\nof about 100 by 200 feet with a drop off to the north where there’s a steep\nslope into a hollow. On a flat below the well is a spring-fed cistern (about\n326 feet from the well according to our GPS). The pit is between the wellhead\nand the drop off and is partially in fill soil.

\nThis is on the same ridge (but a mile north of us) that we live on and we have\nseasonally high groundwater in winter and spring with two ephemeral springs\nclose to the house. It’s possible that the site we’re examining also has a\nperched aquifer with groundwater close to the surface. Some our neighbors,\nuntil this year when city water came to the ridge, depended on spring-fed\ncisterns (like the one below the well site), all at about the same elevation\nbut in different areas, and it’s believed they all are fed by the same aquifer.\nI don’t know if everyone has city water now or if some still depend on\nspring-fed cisterns. The family with the cistern below the well site intended\nto use that cistern for a vegetable garden — their drinking water comes from a\nshallow well fed by a deeper aquifer. It’s possible that these aquifers are\nconnected.

\nThe photographs in The Numbers<\/a> post give an idea of what we saw. The area bare\nof vegetation — the hot spot — is also the lowest spot on the site and has\nponding water.

\nThe well pad is next to a state road with a house opposite. That house is about\n200 feet from the well and pit area and has a vegetable garden alongside the\nroad. Since there is a residence so close to the site and since we believe that\nit’s possible that the pad area might be used as a building lot once the well\nstructures are gone, we’ve considered this a residential site.

\nWe’re also concerned about the ecological effects that the metals and chloride\nwould have on vegetation and wildlife. We’ve seen plenty of deer tracks in the\nhot spot on the surface and assume that deer are attracted to the salts and\nminerals. In our assessment, since deer are hunted and eaten in this area, we\nhave a possible crossover with not just ecological assessment concerns but also\nhuman risk concerns.

\nWe’ll be doing a soil assessment and the factors we’ll be considering include\nwhat the sample metals concentrations are, what the typical background soil\nconcentrations are in this state and then the various screening levels. That\nwill be discussed in the second part. Here’s that link again to the risk\nassessment table<\/a>\nwe’ve created for this site.\n\n\n\n<\/p>\n","protected":false},"excerpt":{"rendered":"

This is a follow-up post to The Numbers where we provided laboratory analysis results for a sample of pit waste at a natural gas well site. Risk assessment is a huge topic so we’ll be splitting the post into two parts. In this part we’ll discuss some features of the site that have to be […]<\/p>\n

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