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11/17/98 17:01 TITROUBBER 4 444 • NO.041 P008/010 4. EXCAVATION • FRpM CDHRRE550R PRESSU+E RELIEF D VILE The installing contractor must take all p2raufions necessary to AfR SUPPLY VALVE RESERvofR Frrriiic Protect employees working in or rwr a tank excavation.These AIR 5UPPLY GAUGE PITC8"OnS should include,but are not limited ro: SERVICE FITTIMa •IOraoon and protection of atter dRy insUlabkas near the excavation before opening the excavation; Means of securing the walls of the excavation; Means of Preventing exposure of emptayees to hazardous fumes from the excavabon: Protection of employees from hazards associated with water FIGURE 2-4 accumulation in de excavation; •Barricades,etc.to prevent UnauMO112e11 vehicle or pedestrian SECONUARY(EXTERNAL)TANK AST traffic; CAUTION:Do not pressures the secondary tank(interstitial space) •Inspection of the eimavabon and surrounding area at least daily. or the primary tank may rupture and rause tank failure. For additional information on WAvaDon,reaching and staring Check the exterior of the tank for monitoring liquid—if liquid is safety practices,consuft OSHA's Construction Industry Standards found,wipe the tank dry and verify that the liquid does not Part 1926,Subpart P reappear. Lift the tank to check the bottom.Do not roll the tank. The minimum dephr of the excavation is normally determined by DANGER:Do not stand under the tank while it is being lifted. the presence Gr absence of groundwater and the presence or When the test is complete,remove the test manifold.Usually absence of traffic at the site.Thrse dimensions are critical to the check the interior of the tank for Rquid.Replace the protective successful installation of a tank and are often regulated by code. covers in the service filling and the reservoir filling. Reter to: •federal,state and 3. BACKFILL AND BEDDING leaf codes Xerxes tanks must be inStalled usingeider •NFPA 30 8 API 1615 Pea Gravel or casted stone which meets the following spcd •figures 41 to co ficatiens. 4-4 below. GENERAL The material is washed and free flowing and mmonns ' 6' to the specification of ASTM C-33 pat 9.1,sizes 6 through 8.No rens x un e ns in Ixarx�I 1 more than 5%(by weight)of the material may pass through a#8 nks sieve, It is recommended that the supplier certify that the material ;;- conforms to ASTM C-33 and any other applicable specifications. cairn rAs (For additional information,refer to the Xerxes pamphlet Rberglass mAFFtc 5nk Back/ll Guidelines.) PEA GRAVEL CRUSHED STONE Il RGURE 4-1 I/8" 1/8 Tanks subjected to traffic loads must have a rover depth of at least 18[36)incites of backfill plus 9 inches of asphalt.An acceptable atterrative is a minimum of 18[35)inches of backfill plus 6 inches of reinforced concrete. ® r9 P 6- FIGURE 3-1 FIGURE 3-2 [ vE cvotr«rs PEA GRAVEL Mix of rounded particles —sizes between 1/8" and 3/4". CRUSHED STONE:Mix of angular particles—sizes between 1/8" WIM,Numbers in brzdrers f l and 12". 12• refer to lZ tanks. NdrE:II maiera rmxtl meets mese SWdubgm is nd avalUble.connect the FIGURE 4-2 xerim EVQI x rep Service Dew,Imeni for Intortmrim m mprovea abnnare roil'—Ua U..N omc,M. R'.o ,.g era=,WkfalWreTsnhs subjected m traffic 10a&8114 high vvaMve r must haa nCSull in 1lank ''e� leruls %Pixel'prpr wnRer'appmral roll roil kne tank viananry and minimum of 30(36)inches of backm and either 9 inches of lln'/ . asphalt or 6 inches of reinforced concrete.