1、API PUBL*4bOO 95 0732290 0544544 bbL HEALTH AND ENVIRONMENTAL SCIENCES E XPLO RATI ON AND PRODUCTION DEPARTMENTS AND API PUBLICATION NUMBER 4600 JANUARY 1995 Metals Criteria for Land Management of Exploration and Production Wastes: Technical Support Document for API Recommended Guidance Values Ameri
2、can Petroleum EnvironmmIal Purrnmbrp I Institute API PUBL*4600 95 m O732290 0594545 5T -I- Environmental Partnerrbip One of the most significant long-term trends affecting the future vitality of the petroleum industry is the publics concerns about the environment. Recognizing this trend, API member
3、companies have developed a posiuve, forward looking strategy called STEP: Strategies for Todays Environmental Partnership. This program aims to address public concerns by improving our industrys environmental, health and safety performance; documenting performance improvements; and communicating the
4、m to the public. The foundation of STEP is the API Environmental Mission and Guiding Environmental Principles. API ENVIRONMENTAL MISSION AND GUIDING ENVIRONMENTAL PRINCIPLES The members of the American Petroleum Institute are dedicated to continuous efforts to improve the compatibility of our operat
5、ions with the environment while economically developing energy resources and supplying high quality products and services to consumers. The members recognize the importance of efficiently meeting societys needs and our responsibility to work with the public, the government, and others to develop and
6、 to use natural resources in an environmentally sound manner-while protecting the health and safety of our employees and the public. To meet these responsibilities, API members pledge to manage our businesses according to these principles: To recognize and to respond to community concerns about our
7、raw materials, products and operations. To operate our plants and facilities, and to handle our raw materials and products in a manner that protects the environment, and the safety and health of our employees and the public. To make safety, health and environmental considerations a priority in our p
8、lanning, and our development of new products and processes. To advise promptly, appropriate officials, employees, customers and the public of information on significant industry-related safety, health and environmental hazards, and to recommend protective measures. To counsel customers, transporters
9、 and others in the safe use, transportation and disposal of our raw materials, products and waste materials. To economically develop and produce natural resources and to conserve those resources by using energy efficiently. To extend knowledge by conducting or supporting research on the safety, heal
10、th and environmental effects of our raw materials, products, processes and waste materials. To commit to reduce overall emission and waste generation. To work with others to resolve problems created by handling and disposal of hazardous substances from our operations. To participate with government
11、and others in creating responsible laws, regulations and standards to safeguard the community, workplace and environment. To promote these principles and practices by sharing experiences and offering assistance to others who produce, handle, use, transport or dispose of similar raw materials, petrol
12、eum products and wastes. API PUBL*4600 95 m 0732290 0544546 Y34 m Metals Criteria for Land Management of Exploration EPA, 1987) that were not included in the EPA sewage sludge risk evaluation are barium, boron, and tin. The risk associated with the land application of wastes containing these metals
13、was evaluated using the same methodology. Summaries of environmental chemistry for each metal may be found in Appendices A-C, respectively. Risk evaluation calculations are contained in Appendix D. The evaluation for tin indicated very low risk; therefore, a guidance value is not warranted. CALCULAT
14、ION OF E however, it is likely that only a portion of the 0.2 grams per day of soil is from pure waste since children are exposed to other sources of household dust and dirt, and from sources of soil away from the home. It is also unlikely that a child would ingest 0.2 grams of pure waste every day
15、(Paustenbach et al., 1993). A third as- sumption is that the biological availability of waste-amended soil-bound pollutants was assumed to be equal to that of the metals in drinking water and food. There is evidence that desorption from the soil particles is a very slow process that generally requir
16、es more time than is available to material that is traversing the alimentary canal. Such desorption would have to take place before the metal could cross the membranes into the blood stream and be transported to sites in the body where it could cause toxic ef- fects. The last conservative assumption
17、 is the use of lifetime reference doses (Rfs) which represent 70 year chronic exposure. This overpredicts the metal dose the child receives relative to the toxic threshold (RfD) used because the lifetime RfDs protect the child for 70 years from ingesting metals in the waste when in actuality the chi
18、ld would grow out of soil eating behavior in approximately 5 years. The risk-based maximum soil concentration for selenium (100 mg/kg) is extremely high relative to typical levels found in drilling wastes (maximum 0.58 mg/kg) and soils (average 0.3 mg/kg). It has been known for many decades that exc
19、essive soil selenium can poison livestock. Generally, livestock toxicity problems occur in alkaline soils under arid and semi-arid conditions where rainfall is insufficient to leach selenium from the root zone and selenium accumulator plants (e.g., Astragalus, Haplopappus, Sfanleya, Xylorhiza, Atrip
20、lex, Casfilleja, Machaeranthera, Sideranthus, Aster, Mentzelia, Bain- bridge et al., 1988) take up and concentrate soil selenium which then becomes avail- able to the animals that eat the plants. If such conditions (arid and alkaline soils on land that may be used for grazing, high selenium waste, a
21、nd naturally occurring sele- nium accumulator plants) exist, then it is recommended that special precautions be taken to prevent poisoning of any livestock. Such precautions may include emplace- ment of waste below the root zone of the soil or active promotion of a good stand of “selenium-safe forag
22、e crops.” The US Department of Agriculture (USDA) has recom- mended that EPA use a maximum soil concentration of 14 mg/kg instead of 100 mg/kg (Chaney, 1994). This non-risk-based value represents the 98th percentile selenium concentration in the National Sewage Sludge Survey. The USDA is comfortable
23、 that this lower limit is both protective and practical based on their experience with land ap- plication of sewage sludge. 15 API PUBL*4bOO 75 = 0732270 05445b4 45T The limiting exposure pathway for five other metals (BI Cr, Cu, Ni, and Zn) is phytotox- icity (Pathway 8, see Table 2). The maximum s
24、oil concentration (threshold value) is the metal concentration that would be associated with a low probability (I x 104) of a 50 percent reduction in young plant growth. This concentration was established from sci- entific data relating the growth of young plants to soil metal concentrations. Phytot
25、oxic- ity by metals is sensitive to changes in soil pH, to the type of plant species, and to the degree of metals binding in the soil/waste matrix. Metals that partition onto the soil/waste matrix are biologically less available. Phytotoxicity from boron is directly re- lated to its soluble form, an
26、d it is for this reason that the guidance for boron is based on a hot water extraction rather than a total metal extraction (see Appendix B). In the sewage sludge regulations, the limiting pathway for molybdenum (Mo) was live- stock ingestion of plants grown in waste-amended soils (Pathway 6, see Ta
27、ble 2). Ex- cessive soil molybdenum in neutral pH soils has been shown to cause nutrient imbalances in livestock through uptake by forage crops (EPA, 1992). The toxicity mechanism is well understood: molybdenum is transformed in the rumen to thiomolyb- date, which binds copper and prevents both copp
28、er adsorption from the intestines and copper utilization within the animal. The most sensitive livestock are cattle and sheep. On February 25, 1994 (59 FR 9050), EPA rescinded the value from this pathway due to technical errors discovered in the data. After livestock ingestion, the next limiting pat
29、h- way would be soil ingestion by children, which would yield a maximum soil concentra- tion of 400 mg/kg. EPA chose instead to set a non-risk-based interim level of 37 mg/kg based on the 99th percentile concentration of Mo in the National Sewage Sludge Sur- vey while it redetermined a value for the
30、 livestock ingestion pathway. The USDA has recommended that EPA use a maximum soil concentration of 27 mg/kg based on the 98th percentile concentration in the National Sewage Sludge Survey (Chaney, 1994). The difference between the EPAs and USDAs approach is simply a matter of policy. Generally, liv
31、estock toxicity problems occur in alkaline soils with excessive molybdenum relative to copper under arid and semi-arid conditions where rainfall is insufficient to leach molybdenum from the root zone. If such conditions exist, then it is recommended that special precautions be taken to prevent poiso
32、ning of any livestock. Such precau- tions may include emplacement of waste below the root zone of the soil or irrigation of the site. However, a review of the copper and molybdenum content of drilling wastes and associated wastes (EPA, 1987; ERT, 1987) indicates that molybdenum toxicity due to E see
33、 Table 4 and Discussion of Limiting Exposure Pathways for further details. 21 API PUBLX4600 95 0732290 0544570 753 = GUIDELINES FOR SAMPLING AND ANALYSIS CHARACTERIZING SOILS AND WASTES Accurate characterization of the metals concentrations of soils and waste is essential for managing the materials
34、according to the API guidance criteria. The largest source of error in this characterization is inadequate sampling. The following sections contain a synopsis for sampling, analysis, and reduction of data from a hypothetical waste site. References are supplied for readers requiring additional detail
35、. DOCUMENTATION OF BACKGROUND SOILS The risk-based API guidance criteria were developed by assuming typical agricultural soil concentrations for background. In some instances, native soils will exceed the API guidance criteria. In general, land treatment of wastes due to their metals content may be
36、unnecessary if the metal concentration is below that of background. For this reason it is essential that background concentrations of metals in soils be characterized when planning waste management activities or site closure. SOIL SAMPLING The goal of sampling is to obtain soils or wastes for testin
37、g that: i) are representative of the unit being sampled, and i) have minimum variability between samples. The de- tails of designing and executing a sampling plan can be obtained from a number of documents (Wilding and Drees, 1983; Petersen and Calvin, 1986; Crepin and Johnson, 1993; Deuel and Holli
38、day, 1994). Rules of thumb for sampling a hypothetical site are summarized below. Pits and Background Soils Pits contents and background soils should be characterized prior to excavation to allow determination of waste application rates. A grid (e.g., 50 X 50 feet) should be devel- oped to avoid sam
39、pling bias. Composite sampling is a very cost-effective way to con- trol sampling variability. Pit subsamples should be collected over 2 foot intervals to a depth to one sample below the waste body. Subsamples from similar depths may be composited from a number of locations to form samples for analy
40、sis. A sketch must be developed to identify areas where composites were collected. Background soils should be analyzed from the potential land application area. Applica- tion sites should be well drained and out of floodplains and wetlands. Additional criteria for land application sites may be enfor
41、ced by state regulators. Background soil sam- ples should be collected from the “A soil horizon or upper one foot and be composited from a number of nearby locations. 23 API PUBLU4bOO 95 = 0732290 0544571 b9T Waste-amended Soils Following waste application, the waste-amended soil should be sampled t
42、o ensure that API guidance criteria were satisfied. Sampling could be performed on a grid basis as described above for pits and background soils. ANALYSIS Soils should be extracted for all of the guidance metals except barium and boron by EPA SW 846 Method 3050 (EPA, 1986). This method extracts all
43、of the these metals from the solid phase into solution and the results are reported as “total metal.” Several studies have shown Method 3050 cannot accurately or precisely measure barium at concentrations of regulatory significance (Deuel and Freeman, 1989; Kimbrough and Wakakuwa, 1991). This proble
44、m is the result of the inability of the acid extraction pro- cedure to solubilize all of the barium in the sample. Barium in soil and waste samples should be analyzed by the “true total barium” method developed for the Louisiana 29-8 regulations (Deuel and Freeman, 1989). Hot water soluble boron (HW
45、SB) is the only boron phase of environmental concern. In order to analyze for HWSB, soil and waste samples should be extracted by hot water as described in Carter (1993). Extracted metals should then be analyzed by ion coupled photometry (ICP) or atomic absorption methodology. The recommended guidan
46、ce concentrations for barium and boron are extremely high relative to typical levels found in E Petersen and Calvin, 1986). The appropriate distribution should be used to determine the proper arithmetic mean and standard deviation of the sample population. The arithmetic mean plus one standard devia
47、tion theoretically contains 84 percent of sam- ples from the population (Figure 2). The critical soil concentration of a waste-amended zone is defined as that which is equal to the arithmetic mean plus one standard devia- tion. The critical soil concentration should be less than the API guidance cri
48、teria. This approach is more protective than using the arithmetic mean concentration and should provide a margin of safety over the uncertainties introducing by mixing and analysis. Some native soils may exceed the API guidance criteria. If this situation occurs, the vi- ability of exposure pathways
49、 should be re-evaluated. 25 API PUBL*4b00 95 = 0732290 0544573 Ltb2 D Waste-amended Soil ! API Guidance f -2 SD -1 SD Mean +1 SD +2 SD Concentration Figure 2: Normal distribution of soil properties plotted in units of standard de- viation (SD). Many soil properties require log-normal transformations to resemble this distribution. API Guidance recommends that the criti- cal soil concentration (the mean plus one standard deviation) of a metal in a waste-amended zone be less than the criteria for that metal.
