ARCHIVED REPORTS_XR0011714 - Laserfiche WebLink

Home Browse Search

322 PETROLEUM CONTAMINATED SOILS ESTIMATES FOR HYDROCARBON VAPOR EMISSIONS 32 iV2 a Emissions Associated with Excavated Pits Scenario 6. A worst-ease treated (45% treatment efficiency)emission nal, of 327 gid, and a release temperature,of 370°C. Scanoiw 1. The maximus»estimated emission rate from the empty pit was Scenan0 7 A more realmttc,t=ted(95%treatment efFiciency)benzene,emt,, estimated to be 58 g1d from a 6.1 m by 12 2 m pit area at a temperature of 20'C stork rate of 4 7 gid, and a release temperature of 370T (see§111 la) Since these emissions are hypothesized to last for three days,the IV 2d Emissions ftin Groundwater Pump& Treat Operations peak 24-h oonoentration was assumed to approximate the highest exposure that might result during Ike three days A ground level emtsswn height was assumed and Frms�i rquid Product Reent+ery SCeriarja 2 A snore realistic average emission rale estimate from the pit was Groundwater and free-liquid product recovery systems uldize various pump calculated to be 22 gid (see§lll la) As for Scenario 1, the pit was assumed to in hardware, Including submergible air-injected pumps These pumps work bi be 6 1 m by 12 2 m, the temperature to be 20°C, and the emission height to g be ground level As in Scenario 1, the 24-h peak exposure was determined. displacing fluid with air, and while the fluid is collected aboveground, the ai is generally emitted untreated Some volatilization may occur during the peri(N+ IV 2b Errmrssions from Exposed Piles of Gasohne-Contaminefad Sorts that air and fluid are in contact, so the released air will be a source of einmssioms The worst case(ntaxtmutn emmssion rate)ocxars when the air and fluid plias+ Scenario 3 The estiniated one-hour average flux rate al ground level from equilibrate during pumping Sceiiano 8 repmesemmrs die case m which the dtschwgci the 6 l m by 6 1 in excavated soil pile was calculated to be 3 0x 10-" glomi'-d air is in equilibrium with free-liquid product containing 1 mole % benzene (ai in§111 ib,for a temperature of 20°C It was assumed that the pile would remain 20"C), whereas Scenarios 9 and 14 describe the cases of pumping gasolme exposed for an 8 h shift, and then be covered at night Therefore, an 8-h peak saturated groundwater(18 ppm benzene for l mole % betizene in gasoline)an concentration was calculated to represent the exposure from the pile groundwater containing a more realistic I ppm benzene,respectively All sc€narrn� assume that the vapor is released from a 0 64-cm diameter stack at a height ri IV 2c ErWsslions from Solt Ventrrmg Operations 5 cm above ground Since pump and treat operations are expected to last for . few years,the annual average was used to estimate exposure levels in suim irtary In a typical soil venting operation,vapors are removed from the soil by a vacuum the following scenarios were analyzed pump and then treated by a vapor Ireatmenl unit before being released to the at � nmosphere In areas with strict emissions regulations,vapiir incinerators and c,ita- Scenario 8 An ati erage benzene emission rate of 0 2b gid (see §lit 1r) 1„r lytic oxidizers are often used in some area-., diffuser stacks are still allowed the Bumping of tree liquid gasoline at a rale of 0 0381Jniin(860 gal aver d t.+m In 1111 Id four enmisswn rates were estiinaled for clic venting operations (a1 a month period) and at 20°C temperature worst-case situation in which it was assumed that there was a nondimmnishing ScenaW 9 Pumping gasoline-saturated groundwater containing 18 ppla bUu gasoline source and the vapors were released without any treatmmieni, (b)a more zene at a rate of 76 Umin(20 gpmn), which results in a maximum emission rat, 560 of realistic case in which it was assumed that 100% of the benzene from a 19(I{) ad at 20°C (see U11 le) nti) 10 Pumping groundwater containing 1 ppm benzene at a rate, +�i L (500 gal) gasoline spill was removed over a six-month period, again with no $CQ vapor treatment, (c)emissions from case (n), except that they are treated by a 76 Lirnin (20 glint),µfilch results in a maxtintim cmtsston rate til 32 gid at 20'( unit with a vapor destruction efficiency i?=0 95, and (d) same as case (b), ex- (see §111 le) cept the vapors are treated by a unit with a vapor destruction efficiency it=0 95 It should be noted that vapor incinerator and catalytic oxidizer units are quite IV 28 Emissions Dire to Aboveground Water Tiaeatmertt capable of achieving destruction efficiencies C95%, so the 95% value used in these calculations Should be regarded as a worst-c.age(ver} onnservative)estimate The maximum vapor emissions for aboveground water treatment systems occ+� All of ItmRe scenarios were modeled asstkming that the vapor was relc.asod iron In air-stripping systems 1n §ll[ if benrene emissions for air-strippers►i�err c,0 a 4 6 m(15 ft)stack with a 0 6 m (2 ft)diameter The total vapor flowrate was culated and presented in Figure 12 For the air dispersion modeling,the follov+ assumed to be 1400 Lfmin (50 SCFN4) for all eases Ing situations were selected Scenario 4- A worst-case untreated emission rate of 6532 gid, and 20°C Scenario 11 A benzene emission rate of 1965 gid for an air-stripper Irc,ii release temperature were assumed ing gasoline-saturated groundwater (18 ppm benzene far I mole % bemrrene u Scenario 5 The more realistic six-month average untreated emission rate of gasoline) at a throughput rale of 76 Umm (20 gpm) `!he air llowrate throikl;l 84 gid and 20'C role-its it itiperalvi c tike %tripper 14. 500 1 Imin (200 SCFh4)