1、American Petroleum 11 Ins titute Management and 3- 2 3.1.1 Landsmeading Disposal by landspreading involves minimal precautions, and simply consists of spreading sludges and scales on the surface of open lands in a prescribed area. A minimum thickness of onequarter inch (0.6 cm) is assumed to be the
2、smallest practical layer thickness that can be applied, and applications of layers up to eight inches (20 cm1 are considered. The area covered may become arbitrarily large for disposal of a given quantity of material. Analyses of landspreading are based on incremental increases of radium concentrati
3、ons above background levels, and thus are restricted to one-time disposal in a given area This suggests record-keeping to avoid repeated spreading in a given area, and possible radiation sweys to characterize pre- and post-spreading radiation levels. Subsequent uses of the affected land are not rest
4、ricted, permitting home construction, agricultural food production, or any other land uses. 3.13 Lanbreaing With Dilution Landspreading with dilution includes mixing of the applied wastes thoroughly within the top eight-inch (20 cm) layer of soil. Since the mixing would utilize agricultural equipmen
5、t of fixed tillage depth, the mixing is defined to extend to eight inches of waste plus soil. Thus maximum dilution would involve 1 inch of waste plus 7 inches of soil, and a maximum deposition may involve 7 inches of waste and 1 inch of soil, or in the equivalent to surface spreading, 8 inches of w
6、aste. The area covered may be arbitrarily large. Analyses of landspreading with dilution also are based on incremental increases of radium concentrations above background levels, and thus are restricted to one-time disposal in a given area. This again suggests record-keeping to avoid repeated use of
7、 a given area, and possible radiation surveys to characterize pre- and post-application radiation levels. Subsequent uses of the affected land are not restricted, permitting home construction, agricultural food production, or any other land uses. 3.13 Non-Retrieval of Surface Pive Surface pipe conta
8、ining scales and sludges may be buried at shallow depths. Upon retirement hm active service, the pipes may be cleaned of petroleum products but left in place for disposal. if left unretrieved, later land uses could involve home construction over the pipe, with possible perforation to expose its cont
9、ents to a crawl-space or basement area. Since surface pipes may be made from minerai fiber, perforation or cutting during construction may go unnoticed. The open pipe may extend for several hundred feet from the structure, and may permit air flow from other perforations through the pipe and into the
10、 structure. A pipe of 3-inches (7.6 an) inside diameter is considered to represent the surface pipe for this disposal alternative. Scale deposits in the pipe are assumed to be 2-1/2-inch (1.3 cm) thick, and to have a density of 3 g/cm3. The house was assumed to be at a negative pressure of 6 Pa rela
11、tive to the atmosphere. 3.1.4 Burial with Unrestricted Site Use Burial with unrestricted site use may occupy any available land area, and have a range of possible burial depths and waste thicknesses. The depth of burial is dehed as the thickness of earthen cover placed over the waste after buriai. T
12、he completed burial site has its cover level with the surrounding terrain, minimizing erosion potenad. Due to the visual similariS of many sludges and scales to natural earthen materials, it is assumed that inadvertent intrusion could occur at the burial site in the absence of permanent institutiona
13、l controls. An 8-foot depth corresponds to an inadvertent intrusion limit that ordinarily is not exceeded by common activities such as excavations for public utilities, house foundations, graves, etc. SubseqU=r; 1sd use for the burial site includes construction of a house with a basement over the wa
14、ste, intersecting the waste layer if it is located within the top 6 feet. For regions ia which homes can have basements, the top 6 feet of cover may not be considered in determining NORM concentration limits. 3- 4 STD-APIIPETRO PUBL 7103-ENGL 1997 = O7322qO ObOL720 574 = 3.1.5 Disoosal at a Commerci
15、al Oil Field Waste Site Disposal at a commercial oil field waste site involves burial with other wastes that may not contain NORM, but would serve to dilute the solid NORM wastes. Since NORM wastes are about 7 percent of total oil industry wastes, it is assumed that dilution by a factor of fifteen o
16、ccurs, and that waste deposits exceed a thickness of 10 feet (305 cm). The completed waste site has an earthen cover that is level with surrounding terrain to minimize erosion. For estimating exposures from transporting wastes to the disposal site, a distance of 100 miles is assumed. 3.1.6 Disoosal
17、at a Licensed NORM Waste DisDosal Site The NORM waste disposal site is defined by the EPA regulations for disposal of uranium and thorium mill tailings and related byproduct materials.“) It is designed to be effective for loo0 years to the extent reasonably achievable, or in any event, for at least
18、200 years. It is designed to limit radon fluxes to the atmosphere to 20 pCilm*/s, averaged over the disposai area and over any one-year period. The impoundment usually is designed with an earthen cover for radon control and suitable liners and siting criteria to protect local groundwater from contam
19、inant leaching and migration. After closure, the site is deeded to the state for permanent monitoring and restricted future use. No intrusive activities or construction of occupiable structures on the site are permitted. For estimating exposures from transporting wastes to the disposal site, a dista
20、nce of 300 miles is assumed. 3.1.7 Disposai at a Licensed Low-Level Radioactive Waste Disposal Site The low-level radioactive waste (UW) disposal site is debed and licensed under Nuclear Regulatory Commission regulationd3) with numemus protective featues and restrictions that ultimately restrict the
21、 feasible locations and numbers of such facilities. Presently there are only three LLW facilities in the United States (Hanford, WA; Beatty, W; and Bamwell, SC), although others are being considered by some states and interstate compacts. Due to the limited number of LLW sites, transportation of was
22、tes to the site also 3- 5 STD.API/PETRO PUBL 7103-ENGL 1997 = O732290 Ob01721 400 = must be considered. A haul distance of 900 miles is assumed. Future site uses are restricted from intrusion, and site features are sufficient to warn the inadvertent intruder of the presence of anomalous materials ev
23、en without institutional control. 3.1.8 Burial in Surface Mines Burial of NORM sludges and scales in surface mines involves placement at the bottom of mine excavations and subsequent burial by accumulated earthen overburden. Typical burial depths are 50 feet (15 m) or greater, and areas are sufficie
24、nt to accommodate relatively large volumes of wastes. Because of the significant burial depths, the potential for erosion or intrusion into the wastes is remote. No land use restrictions are applied related to the NORM content of the wastes. 3.1.9 Plueged and Abandoned Wells Well tubing with accumul
25、ated scale may be left in place or placed in a well being plugged and abandoned. Scales in the tubing remain nearly completely inaccessible hm surface intrusion. Reclamation of the weil site includes sealing several feet of the well with concrete grout or other suitable material, preciuding signific
26、ant access to materials at greater depths or surrounding formations. The well is capped, preventing inadvertent intrusion into th well. 3.1.10 Well Iniection Well injection consists of injecting slurries of the sludges or scales into a deep permeable formation below underground sources of drinking w
27、ater (USDW) with no fresh water or mineral value. The formation is confined by impermeable layers that are likely to remain intact. Therefore formations selected for injection are limited to areas and horizons in which deeper formations also have little or no economic value. The injection is consist
28、ent with EPA standards for underground injection controls for Class II wells.(“ DuNig - 3- 6 STD.API/PETRO PUBL 7103-ENGL 1997 0732290 Ob01722 347 operations and at closure, the injection facility is monitored for leakage, and at closure, cement and clay are used to seal the top region of the well.
29、The well is cut below the pun surface and capped, preventing inadvertent intrusion into the injection well. 3.1.11 Hvdraulic Fracturing Hydraulic fracturing consists of adding sludges and pulverized scales to a carrier fluid (typically brine) and pumping the mixture into a well at suKciently high pr
30、essure to create a fracture in a permeable formation below ail USDWs. The hcture formed by this process is normally vertical, confined above and below by impermeable shale formations, 0.5 m thick, and extends several hundred feet hm the well. After the scaldwater mixture is displaced into the fractu
31、e, pressure is reduced and the fhcture closes. The scale is trapped between the fracture walls and is incapable of re-entering the well bore. A well used for this purpose can be fractured multiple times. When the well is no longer required for this or any other purpose, it is plugged with cement to
32、prevent migration of fluids in the well bore. Hydraulic fracturing has been used to dispose of intermediate level (3x10 pWg) radioactive wastes.(1s) 3.1.12 Iniection into Salt Domes Salt dome cavities have been used to store petroleum products, and have been proposed for disposal of intermediate and
33、 high level radioactive wastes due to their inherent isolation of the wastes hm groundwater and hm the surrounding environment. The salt provides impermeable containment of the wastes at depths of hundreds to thousands of feet. The salt formation QGCS ;u self-anneal any containment defects that may
34、occur, further assuring containment of the wastes. Sludges, scales, and equipment containing NORM can be placed in the salt domes. No site restrictions are applied. 3-7 3.2 ALTERNATIVES FOR EQUIPMENT CONTAINING NORM Alternatives for disposal or use of equipment containing NOR34 residues include rele
35、ase for general use, release for re-use within the petroleum industry, storage in an oil-field equipment yard, release for smelting, and burial with NORM scales and sludges. Selection among these alternatives depends in part on the quantity of NORM remaining in the equipment. For example, release fo
36、r unrestricted use requires that any residual NORM is at very low levels, while burial with NORM scales and sludges permits potentially higher concentrations of NORM residues. 3.2.1 Release for General Use General use of petroleum equipment could occur under a v&ety of conditions. A conservative but
37、 plausible scenario for exposure to NORM remaining in former petroleum equipment is that of residential use of the equipment. It is assumed that a piece of larger pipe or other equipment containing scale is used inside the house for structural support of a floor, ceiling, etc. Residents in the house
38、 are assumed to spend 2.2 hours per day within one meter of the structural pipe or equipment containing NORM. Thus, they are exposed 800 hodyear to gamma emissions hm the indoor NORM as well as continually to the radon gas generated. 322 Release for &Use Within the Petroleum Industry Simple release
39、of equipment containing NORM for re-use within the petroleum industry constitutes a null action, since continued use constitutes non-disposal and since the equipment eventually Will be either cleaned or disposed appropriately by the new owners. Therefore, the buyer should be informed of the presence
40、 of NORM in the equipment. STD.API/PETRO PUBL 7L03-ENGL 1997 m 0732290 ObOL72Li LLT 33.3 Storage in an Oil-Field Equhment Yard Oil-field equipment removed fhm service frequently is stored in oil-field equipment yards. This may be for cleaning, refurbishing, transfer to other fields, sale to other co
41、mpanies or for other uses, or disposal. As a result of this storage and the associated handling of equipment, both equipment yard employees and offsite residents potentially are exposed to gnmma emissions and respirable dusts hm NORM in the equipment. The equipment may be capped to contain any sludg
42、es and scales, or may be left open. Yard workers spend about 500 hours per year near or worhg on the equipment. Adjacent residents also are exposed to gamma radiation and dusts fMm the yard. 35.4 Release to a Smelter . Although some smeitiag operations may produce steel for new oil-field equipment f
43、rom old equipment that contains NORM, other operations may produce consumer products in which residual NORM is more significant. When separated by smelting, residual NORM mainly accumulates in the slag. The smelting alternative is dened to produce water pipes and eng pans for public use, potentiatin
44、g the gamma and ingestion exposure pathways. This use of iron containing radioactive materials is specified by the NRC in the IMPACTS- BRC methodoio-.() The smelting process produces airborne dust that is respirable by both onsite workers md offsite residents. Slag from the smelting process is withi
45、n gamma exposure proximity to workers and also produces respirable dust. 36.5 Burial with NORM Sludges and Scales Equipment containing residual NORM scales may be buried under any of several disposal alternatives with sludges and scales that contain NORM. When the NORM is still deposited in equipmen
46、t, however, the waste properties differ from those of the separated sludges and scales. Equipment that could be buried with NORM wastes was categorized and estimated to result in a disposed bulk density of 4 g/cm3, with a porosity of 0.5. Production equipment included in this estimate included flow lines, manifolds, meters, pumps, separators, stock tanks, vapor recovery units, injection wells and pumps, production wells, 3- 9
