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Home My WebLink About2\ 7// Prs"Yt a t, !-E0;o{ C +t r€4,(s tr; tj -J:i' J t il FI*abh C onsultants 1OO TOSCA DRIVE STOUGHTON' MASSACHUSETT9 O2Q72 TELEPHoNE 6171344'laoo TELEX 92'4486 April L6, L976 Mr. J. B. Castner Construction Manager Pacific TelePhone ComPanY Lg25 East Dakota : Room 216 ltresno, cal-ifornia 93VZL Dear Mr. Castner3 *ours'. t'rul1r, of 'the results obtained d'uring yourThis is Your final rePort recently completed Heath Special Investigation' ; fhe'report of surveY followin! wilr nl* vou further=ff:|:t:r"oo- ."'"i"gyourinvestigation.Shou1d}rbuh.v.eanyq:"----_- corrunents regard'ing trre investigation or lhis report, pleasg con- tact us and refer to the reference number'' .' We appreciate ttris opportunit'y to. be of, ser.'::: to you and look - ' forrrard to serving you again in ttre'near future" ' Paul M. Eeim viee President OPerations pm -.+-&J.,----*- -- 1., SPECIAL INVESTIGATION FOR PACI FI C TELEPHONE COMPANY SAN LUIS OBiSPO, CALIFORNIA Reference Number: . 6-CAL--1 I 3-SP -697 I. INTRODUCTION From March 2, 1976 to March 12, 1976, a Speci a1 Investi gati on w.as conducted for thE P.acific Telephone CompdrV, 21 35 Parker Street, San Luis 0bispo,'California. Tie investigation was requested'by ': Mr",:.1_e1ry Cas!nern Constluction Manager; for the purpose of ,deter- m.ining lhe origin of gasoli.ne entgring telephone calf .-ducts and . manholes'onMon'ter.eyStreetinSan-Luis.0bispo.. Presence of gasoline in the cable ducts'had been initi'a11y experienced late in .l975, in the manholes at Monterey Street and Johnson Avenue. Subsequently, guffiping openations to remove Water resulted in ign'ition of accumulated ga!oline and p,ersonal injuries as wel I as cabl e dama.ge. in an effort to remove the gasoline and avoid further infil- tr"ation into cable duc.ts, a drain l.ine was,installed parallel. to. the.cable ducts along Monterey Street, terminating in a collection s ump north 9f Johnson Avenue. Peri odi g pumpi ng by the San Lui s 0bispo Fire Departnient resuTted in the removal of over 1,000 ga1 'lons of gas ol i ne f rom the manhol es an d s ump i n the three mon thS starting December 4, 1975 H i rg ',3 Speci a1 Investi gati on (cont'd) Pacific Telephone Company Reference Number: 6-CAL-l I 3-SP-697 Page 2 r ; I n An analysis of a sample of the gasoline, conducted by the t^Iestern. 0i.l and Gas Associat,i on , i ndi cated. a refi-ned product wi th a formulation at least two years old. Attempts by hlestern 0iI and Gas Association to locate the source of the gasoline were inconclusive. I.I " TEST PROC.EDURE Testing for the source of gasoline entering the cable ducts was conducted by locating and,defining the area of,gasoline vapor''-. presence in the soil. Pr"esenee of'vapor at the 34,' test depth is taken as an i ndi cator of present or recent presence of I.i qrii d . i.. - : gasol ine at thi s or greater depth Tests were made w,ith a combustibre Gas In.dicator (N-.s:A. Model #53 Gascope) on air samples drawn from a unifor:m depth of thirty-four (34), inches below the surf,ace" Test hol.es initially were p'laced at ten (10) foot intervals along the east edSe of the ..east sidewalk on Monterey S-treet, with subsequent test ho'les , , - j -- :p'laced as neede'd to'e'stablish f'imits :to the area of 'vapo" oresence. l,rlhere tests with the Combustible Gas Indicator were negative,': additional tests were made wi-th a Flame-Ionizatioh Hydrocarbon Detectoro for confirmation with the more sensitive instrunr,ent. Initfat tests were conducted on March 2,1976. These were interrupted by a heavy storm which caused high levels of Sround 'i I t lH- Speci a1 Investigation (cont'd) Pacific Te'l ephone Company Reference Number: 6-CAL-l I 3-SP-697 Page 3 water and di storti on of the i ni ti al vapor. I evel r9.adi ngs. Tests were resum.ed on March 1l; after determining that retest of the same test points corresponded to the results of March 2, the com- p1 ete seri es of tests was conducted. Because property owners were not avai I abl e to gi ve permi ssi on for these tests, authorization was granted by San Luis 0b'ispo Fire Chief, Lbe Schlobohm, for testing on private prooerty under Fire Department Power of Emergency Access. Chi ef Schl obohm's authori - zation memo is included.with this report.': III. TEST RESULTS Results of the tests are shown in the attached drawings. Figures indicate combustible gas readings at a 341'test depth. hlher.e a single f igure is shown a sustained reading was obtained; where two figures appear, the upper is the peak level obtained, andthe]oweristhesustaine.djevel.. AII tests'were made with a Mine Safety Appliances' Model #53'' : Gascop€, calibrated on methane. Figures followed by the letter "G11 are percent levels of gas (vapor) in ai.r; aJl other figures '1 are percentages of the lower explosive l'imit. (Th.us a read'i ng-of .l00 is approximately equal to I C.) tr, aJ P R P peci al I aci fi c T eference age 4 nvesti gati on (cont'd) e1 ephone ComPanY Number: 6-CAL-l I 3-SP-697 in the soil are highest in a band extending from the:sidewalk edge between precision Engineering and Yamaha of San Luis 0bispo' east into the Cuesta Service Station. Readings along the east edge of the sidewa'lk show a gradual increase, from negative in front of Holland Real Estate to a peak in front of Yamaha of San Luis 0bispo, and a decrease proceedinS, north, with negatiVe readings c'lose to Pepper Street Readings appearing at !he Cuesta Service Station close to the Monterey Street-Pepper Street intersection were determined to result.from a probab'le n.atural gas leak from the Southern Calif- ornia Gas Company main which lies approximately six (6) feet from the test points. (This distinction is made possible by taking r"eadings both with and without a condensible Hydrocarbon Filier, whi ch passes natural gas and traps heavi er hydrocarbons , i ncl udi ng gasoline vapor.J No,gasoline vapor was found at the tntersection. Tests were made in Monterey Street at the eas.t curb line. ' :.: However, because of vapor di spers i on thrrough the perforated drai n Iine, only one foot away, these tests'were inconclusive and are not entered on the drawing. Tests were made aiong the west side of Monterey Street between Stanley Motors and Penper Street, at the northwest corner of Mon- terey and Pepper Streets, along the north and south sjdes of Pepper Street wi thi n the area occupi ed by the Cuesta Servi ce T H n Spec'i a1 Investi gati on (cont ld) Paci fi c Tel ephone Company Reference Number: 6-CAL-113-SP-697 Page 5 Stati on and al ong the east si de of the Cuesta Stati on. Al 1 of these tests w:re negati ve, wi tlr the excep,tion of the natura] gas readings mentioned above. it appears, on the basis of all tests conducted, that the gasoline detected within cable ducts on Monterey Street has its origin within the pump island and storage tank area of the Cuesta Service Station and is en.tering the cable ducts at a point approx- rth curbline of PepPer Street. Because no tests could be made within the pump and tank area of the station (due to the danger of damage to electrical lines and fiberglass gasoline lines) it is impossible to further pinpoint the point of origin, also, these tests cannot distinguish between current leakage and resi dual gasol ine from a previously repai red leak IV. RECOMMENDATIONS The c0rreeti've measure most often employed in such situations is,placementr'of a drain line to intercept the flow of, gasoline and carry it into a collection sump for removal. This has a'l ready been done and has been qu'ite effective in reducing gasoline levels i n the Monterey Street cable ducts . To speed thb proceSs , these additional steps are suggested: l. ) P'l acement of one or more additiona'l drain 'l jnes within the Cuesta Service Statjon, similar to that a'lready installed on Monterey Street. These couj d be connected into the Monterey Street line, ot a separate collection sump could be provided at the lowest r& : .i Spaeial Investigation (cont'd) Paci fi c Tel ephone Company Reference Number: 6-CAL-l t 3-SP-697 Page 6 pojnt of the service station property. 2.),Installation of a vent-stack on the service station property to draw gasoline vapor from the soil and disperse it into the atmosphere. If such a vent were connected to underground drains (as described above) and equipped with an electrical fan s ui tabl e for expl os i ve vapors , vapor removal from the soi'l shoul d be expedi ted " It is recommended also, that Gulf 0it Compdry, owner of the Cuesta Station, be asked to test a'l I tanks and I f nes for leakage or to provide assurances that such tests have been successful 1y conducted recently. (Because Gul f is known to have repl aced the tanks and renewed lines, it is likely that such test results are already available.) Tank tests:should be done using the Kent-Moore test procedure; Heath Consul tants Incorporated is prepared to con- duct such tests i f desi red. It is also iuggested that Pacific Telephone Company:rrange to make available to work crews a combustible gas indicator cali- brated. for gasoline. for use in monitor.ing this. o.r ,any other. ca.se of known or suspectgd gasolin.e vapor in manholes.. - Heath Consultants Incopporatedi:preparedtoprovide.asuitab.leins-trumento-rto properly calibrate an instrument ("E'r gas indicator or equivalent) provi ded by Paci f i c Te'lephone. frct F,c TF(€FHoLrf C. J4id AurS cRrsFo, CA DPAc,rlar< '* I o\9 \tr . . - .- .--i- - ' _- __ _- -:--l i /$q,' 3t r' 'ttI '2d T€slv N€Gr"trttrt llr8 SQUr\nnS PEn lNCrr-QUAI]. -l1fh (}\ -l6 rhf\ ]jf ,1 \ -1 i_ q. I c r'! 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