Tank ID: SKYFARM III, TANK NO.2. Town of Hillsborough, California 1600 Floribunda Avenue Hillsborough, CA 94010

Transcription

1 Tank ID: SKYFARM III, TANK NO.2 Town of Hillsborough, California 1600 Floribunda Avenue Hillsborough, CA Out of Service Visual Inspection For AWWA D100 Water Tank Prepared By: Crosno Construction Inc. 819 Sheridan Road Arroyo Grande, CA (805) Date: April 28, 2009

2 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Table of Contents Page 1.0 Objective Description Summary and Repair Recommendations Foundation Bottom Shell Rafters Columns Roof Plate Nozzles Appurtenances Coatings Structural Analysis Tank Out of Service Inspection Checklist.. 9 Appendix A Field Inspection Worksheets Bottom Coating Condition Shell Coating Condition Rafter Coating Condition Column Coating Condition Nozzle Coating Condition Appurtenances Coating Condition Roof Interior Coating Condition Roof Exterior Coating Condition Bottom Steel Thickness Map Shell Steel Thickness Map Page 1 Marlborough Tank No.2 Town of Hillsborough

3 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Appendix B Appendix C Appendix D Photos Structural Analysis Calculations Coatings Material Lab Analysis Page 2 Marlborough Tank No.2 Town of Hillsborough

4 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) OBJECTIVE Crosno Construction Inc. is contracted with the Town of Hillsborough to inspect the Skyfarm III Tank No. 2 water tank. The scope of the inspection is to perform a detailed visual inspection of all interior and exterior exposed features of the tank including the condition of the steel plates, rafters, columns, welds, foundations, vents, anchor bolts, ladders, guardrails, piping and other appurtenances. Physical testing is not required except for ultrasonic steel plate thickness testing in spot locations. An evaluation of the coatings and presence of corrosion will be done by visual inspection on the interior and exterior of the tank. The visual examination will be used to assess the extent of corrosion and type of coating. An independent agent will be employed to sample and test the coatings for lead content. Spot thickness testing of the steel plate materials will be performed to determine the current condition of the Tank with regard to corrosion, especially in the lower portion of the first ring where a concrete collar has been poured against the steel ring on the exterior. A visual structural inspection of the interior and exterior of the tank is used to perform an evaluation of the structural design and condition of the tank to withstand gravity and seismic loadings in accordance with the latest criteria cited in AWWA D The evaluation considers all structural elements of the tank including the foundation, side walls, and roof, however, this is not a fitness-for-service evaluation. Tank Inspection: Field Inspection: Structural Calculations: Wade Crosno, Crosno Construction, Inc. Ray Crosno, Crosno Construction, Inc. Ty Hagen, P.E., Hagen Engineering International Coating Inspection: Dan Smith, Crosno Construction Inc., NACE Level 3 Page 3 Marlborough Tank No.2 Town of Hillsborough

5 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Description General Owner: Town of Hillsborough 1600 Floribunda Avenue Hillsborough, CA Location: Skyfarm III Tank No. 2 Reference: Skyfarm III Tank No. 2 Contents: Potable Water Manufacturer: Pittsburgh Des Moines Steel Company Year Built 1972 Last Coated: Unknown Last Inspected: October, 2007 Last Cleaned: October, 2007 Dimensions: Tank Dimensions: 70ft-6in diameter x 27 ft high Capacity: 700,000 gallons Name Plate Design Basis: None available Overflow Height: 24 ft Geometry: Foundation: Anchorage: Bottom: Roof Type: Access: Internal: External: Coatings: Bottom Interior: Shell Interior: Shell Exterior: Roof Interior: Roof Exterior: Concrete Ringwall Footing? Concrete collar added on tank exterior (42 high x 42 wide) (Unknown, Concrete Collar obstructs view) Flat Knuckle Ladder Ladder (lower 8 cut off for security) Hot-applied Tar Hot-applied Tar, with epoxy touch-up Alkyd Appears to be epoxy, with epoxy touch-up Alkyd Page 4 Marlborough Tank No.2 Town of Hillsborough

6 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) SUMMARY AND REPAIR RECOMMENDATIONS 3.1 Foundation: The concrete collar added around the lower 42inches of the tub ring appears to be sound and in fine condition. The presence of a ringwall footing and the condition of the original foundation system is buried by the subsequent collar and therefore unknown. 3.2 Bottom Based on visual inspection and steel plate thickness measurements, the floor appears in generally sound condition with blistering in about 20% of the areas. There is minor surface rusting at the blistering locations, but the ultrasonic thickness testing did not indicate more advanced deterioration of the steel plate. The thickness measurements were all consistent and above Spot repair of the bottom coatings could be performed now to address the blistering areas. If the blisters are addressed, it appears the bottom could go for another 5 10 years without significant attention, especially if the cathodic protection system continues to perform. However, if the tank interior is getting recoating work in other areas, such as the rafters, roof, or shell, we recommend that the floor be stripped and recoated as well. 3.3 Shell Based on visual inspection and results of spot steel plate thickness testing, the tank shell steel plate material appears sound. The shell interior coating is in moderate-to-poor condition, but the steel material is still very sound and corrosion is not very active. The shell exterior coating is also in moderate-to-poor condition, but also is not exhibiting very much corrosion just minor surface rust spots. Specific attention was paid to the area of the shell plate buried by the exterior concrete collar during the ultrasonic thickness testing. The readings did not reveal any significant material degradation behind the concrete collar. Corrosion of the shell material is not significant at this point, but both the interior and exterior coatings are degraded to a level that will lead to further corrosion in the future if not addressed. The cathodic protection system appears to be function well, as there is still only low corrosion activity though the coatings have significant failures. As part of an overall long-term maintenance plan, stripping and re-coating the interior shell of this tank should be considered in the coming years. Though there is not significant corrosion at this point, the continued life cycle of this tank can be prolonged by maintaining the integrity of the coatings. Maintenance coating of the exterior would be relatively minor at this point; spot prep, pressure washing, and top-coating would be recommended to avoid development of more significant rust. 3.4 Rafters The rafter coatings show significant deterioration in various areas throughout. With the exception of the areas near the center vent, the rafter steel material is still relatively sound, but some advanced corrosion is progressing. The rafter ends near the center vent are significantly corroded. The complete extent of steel degradation is difficult to determine without abrasive-blasting the corroded areas down to clean metal. At minimum, recoating of the rafters and caulking any gaps is recommended in the very near future to stop the current material degradation due to corrosion, and further structural measures may be necessary as Page 5 Marlborough Tank No.2 Town of Hillsborough

7 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) well. If the rafter ends at the center vent are too far degraded, a larger dollar plate and center cone could be inserted to support the rafters further out, and the degraded rafter ends could be trimmed off. Corrosion near the center vent is very common due to the moist chlorinated air flow, but part of the corrosion issues could be due to rafter crowding at the dollar plate. The current dollar plate is not large enough to allow the rafters to all sit flush and side-by-side, so instead the rafter flanges have been overlapped and nested together which leaves many small gaps. These small gaps are impossible to coat adequately and will be prone to hold moisture, which allows for easy corrosion. The rafter-to-roof joints could be caulked during a recoating project as well to further prolong the protection of the structure. The hardware shows the beginning of advanced corrosion as well and should be replaced if a re-coating project is performed. 3.5 Columns The center column coal tar coatings have failed and surface rust is blossoming but material deterioration does not appear to be significant. Recoating is recommended before material degrades further. 3.6 Roof Plate The roof interior coatings show advanced deterioration along with the rafters and center column. Virtually all of the coatings have failed, with significant surface rust throughout, rust along 90% of the roof lap joints, and pitting progressing in 40% of the areas. The roof exterior finish coating is 70% deteriorated, with the prime coat showing through significantly in all areas. There are various surface rust blooms and several gouges in the plate material. The center vent has been modified with a galvanized sheet metal skirt, so corrosion underneath is unknown, however the exposed coatings on the top of the vent show significant failure. The degradation of coatings on the roof interior is advanced and should be addressed promptly to halt further steel corrosion and degradation. The existing coatings should be fully stripped and recoated. The shell to roof joint near the compression ring should be caulked. The roof plate lap joints could also be caulked to further protect the structure from corrosion. The exterior coating also shows significant degradation and should be prepped and recoated. The roof plate material does not appear to be significantly degraded and can still be maintained with the replacement of the current coatings. The existing CP, level gauge, and roof hatch hardware could be replaced during a rehabilitation project as well before it begins to fail due to corrosion. 3.7 Nozzles A 10 flanged inlet, (2) 8 flanged inlets, and a 4 flanged inlet were observed. From the interior, some rust bleeding was occurring at the nozzles, especially near the epoxy-to-coal tar interface. The nozzles appear in satisfactory condition on the exterior, although their condition is unknown in the area that passes through the concrete collar. 3.8 Appurtenances There are interior and exterior ladders, with a galvanized Saf-T-Climb on the exterior. Both appeared in fine condition. The 24 x24 roof hatch is in fine condition, but the hardware should be replaced during the next rehabilitation project due to progressing corrosion. The overflow is 8 round with a small weir box at the entry and exits the tank through the bottom. The level-gauge is full-travel but is in major disrepair; the gauge board is missing hardware, the target is unattached, and the cable system is not working properly. Page 6 Marlborough Tank No.2 Town of Hillsborough

8 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Coatings The coatings conditions are as detailed in the individual items above. In general, both the original interior coatings and exterior coatings are in need of repair in order to maintain the longevity of the tank. The interior coal tar coatings should be stripped completely and re-applied with current epoxy products; the exterior coatings may be pressure washed and spot prepped prior to application of a current top-coat product. Page 7 Marlborough Tank No.2 Town of Hillsborough

9 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Structural Analysis See Appendix C for the Structural Analysis Calculations. The following is a summary of the analysis. Bottom: The required bottom plate thickness is based on a minimum nominal thickness of ¼. The bottom plate is not a structural element and its thickness is not based on calculations. The allowable minimum thickness for an existing tank is based on judgment. The API STD 653 Standard for the Inspection and Repair of Oil Tanks specifies a minimum thickness of The minimum bottom thickness measured is greater than The bottom is adequate. Shell: The minimum shell thickness is based on a minimum nominal thickness of ¼ or a calculated thickness. The minimum shell thickness based on calculations is The measured shell thickness exceeds this thickness. The shell is adequate. Shell Wind Stability: Shell is adequate for 120 mph (3 sec gust). Roof Plates: Roof plate thickness is based on a minimum nominal thickness of 3/16. The number of rafters (spacing of rafters) is based on the roof loads and the roof plate thickness. Based on the number of rafters and the roof loads the minimum roof thickness is Localized pitting is allowed. The roof plate is adequate. Roof Rafters: The size of the rafters is based on the bending moment caused by the roof loads. Due to the size of the tank, the bending moment is very small and a small section modulus for the rafters is required. The roof rafters are adequate. **Attention should be paid to the condition of the rafters ends near the center vent. Without attention and the halting of current material degradation, the structural integrity of the rafters may not continue to be adequate. Seismic: Per AWWA D & D100-05, there is no uplift due to seismic forces and therefore no overturning. Page 8 Marlborough Tank No.2 Town of Hillsborough

10 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) Tank Out-of-Service Inspection Check List ITEM Overview a. Check that the tank has been cleaned, is gas free, and X safe for entry. b. Check that the tank is completely isolated from X product lines. c. Check that the roof is adequately supported, NA including fixed roof structure and floating roof legs. d. Check for presence of falling object hazards, such as X corroded-through roof rafters or appurtenances, ledges etc. e. Inspect for slipping hazards on the bottom and roof X decks. f. Inspect structural welds on access ways and clips NA g. Check surfaces needing inspection for a heavy-scale NA build-up and check weld seams and oily surfaces where welding is to be done. Note areas needing more cleaning, including blasting. Completed Comments WATER TANK h. Review cathodic protection potential readings. OUT OF SERVICE Tank Exterior a. Inspect appurtenances opened during cleaning X b. Hammer test or ultrasonically test the roof NA Bottom Interior Surface a. Using a flashlight held close to and parallel to the bottom plates, and using the bottom plate layout as a guide, visually inspect and hammer test the entire bottom b. Measure the depth of pitting and describe the pitting appearance (Sharp edged, lake type dense, scattered etc.) NA NA Visual only c. Mark areas requiring patching or further inspection NA d. Mark locations for turning coupons for inspection NA Visual only e. Inspect all welds for corrosion and leaks, particularly X Visual only the shell-to-bottom weld f. Inspect sketch plates for corrosion X g. Check condition of internal sump, if applicable. Standing liquid should be removed from the sump to allow for complete inspection and vacuum testing of X No Vacuum testing performed Page 9 Marlborough Tank No.2 Town of Hillsborough

11 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) weld seams as appropriate. Sump bottom and sidewall plate and seams need to be evaluated for both productside and soil side corrosion h. Locate and mark voids under bottom X NONE i. Record bottom data on a layout sketch using the existing bottom plates as grid. List the number and sizes of patches required. X NONE REQUIRED j. Vacuum test the bottom lap welds NA Visual only k. Hammer test or ultrasonically examine any slightly NA Visual only discolored spots or damp areas l. Check for reinforcing pads under all bottom attached X NONE clips, brackets and supports. m. Inspect floating roof leg pads for pitting or cutting, NA and excessive dimpling (indicating excessive loading) n. Check the column bases of fixed roof supports for NA adequate pads and restraining clips o. In earthquake zone 4, check that roof supports are not welded down to the tank bottom, but are only restrained from horizontal movement. NA p. Check area beneath swing line cable for indications of cable cutting or draglines q. Mark old oil and air test connection for removal and patching. r. Identify and report low areas on the bottom that do not drain adequately. s. Inspect coating for holes, disbanding, deterioration, and discoloration. Shell Seams and Plate a. On come up bottoms, closely inspect and gauge the depth of metal loss on the lower 2 in to 4 in of the shell NA NA X X NA NORMAL SEE COATINGS REPORT Visual Only (are of standing water) b. Measure the depth of pitting on each course NA Visual Only c. Inspect and estimate the amount of metal loss on the Visual only heads of rivets or bolts d. Inspect shell-to-bottom lap joints X OK e. Inspect for vertical grooving damage from seal NA assembly protrusions. f. Inspect existing protective coatings from damage, X deterioration, and disbanding. g. Check for areas of rubbing (indicating too much pressure by the seal assembly shoes or inadequate NA SEE COATINGS REPORT Page 10 Marlborough Tank No.2 Town of Hillsborough

12 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) annular space) h. Visually inspect the shell plates and seams for indications of leakage. i. If the shell has riveted or bolted seams, record the leak locations by film or chart in case the locations are X NA NONE lost during surface preparation for paintings. j. Measure annular space at 40ft intervals NA k. Survey the shell to check for roundness and plumb. NA Visual only Shell-Mounted Overflows a. Inspect overflow for corrosion and adequate screening b. Hammer test or ultrasonically examine to check for thin areas, particularly in the vapor space of floating roofs and at edge of roof on cone roof tank. c. Check all clips, brackets, braces, etc, welded to the roof deck plate for welded reinforcing pads and see that they have not broken free. d. If no pad is present, penetrant test for cracking on the weld or deck plate e. Inspect for protective coating for breaks, disbondment, and deterioration. f. Spark test the interior surface coating if recoating is not planned Fixed Roof Support Structure a. Inspect the support columns for thinning in the upper 2ft. b. On API columns (two channels welded together) check for corrosion scale breaking the tack welds, unless the joint between the channels is completely seal welded. c. Check that the reinforcing pad on the bottom is sealwelded to the tank bottom with horizontal movement restraining clips welded to the pad. d. Determine if pipe column supports are concrete filled or open pipe. If open pipe, check for a drain opening in the bottom of the pipe X NA X NA X NA NA NA NA NA Visual only Visual only SEE COATINGS Visual only Visual only Floating Base plate with angle clips e. Inspect and gauge rafters for thinning, particularly near the center of the roof. Report metal loss. Visual Metal Loss at Center Vent f. Check for loose or twisted rafters. X Ok, recent rafter tie work g. Inspect girders for thinning and check that they are NA Single bay attached securely to the top of the columns. h. Report if the columns have cross bracing in the area NA Page 11 Marlborough Tank No.2 Town of Hillsborough

13 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) between the low pump out of the top of the shell (for future internal floating roof installation) i. Inspect and report presence of any roof-mounted swing line bumpers. j. Photograph the roof structure if no rafter layout drawings exists. Fixed Roof Appurtenances Inspection and Light Hatches a. Inspect the hatches for corrosion, paint and coating failures, holes, and cover sealing. b. On loose covers, check for a safety chain in good condition. c. On light hatches over 30 in. across, check for safety rods. d. Inspect the condition of the gaskets on bold or latched down hatch covers. Staging support connection a. Inspect the condition of the staging support for corrosion NA X X X X X NA Breathers and Vents a. Inspect and service the breather. NA b. Inspect Screens on vents and breathers X Emergency P/V Hatches a. Inspect and service pressure/vacuum hatches. (Setting should be high enough to prevent chattering of breather during normal operation. See breather manufacturer s guide) NA b. Inspect liquid seal hatches for corrosion and proper NA liquid level in the seal Sample Hatch a. Inspect sample hatch for corrosion. NA b. Check that the cover operates properly NA c. If the tank has no gauge well, check for a hold-off distance marker and check measurement. NA See report & worksheets NONE None Page 12 Marlborough Tank No.2 Town of Hillsborough

14 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) APPENDIX A FIELD INSPECTION WORKSHEETS Bottom Coating Shell Coating Rafter Coating Column Coating Nozzle Coating Appurtenances Coating Roof Interior Coating Roof Exterior Coating Bottom Steel Thickness Map Shell Steel Thickness Map Page 13 Marlborough Tank No.2 Town of Hillsborough

15 Area Inspection: Bottom Date: 28-Apr-09 Hazardous Material Test Performed? Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Yes, see separate lab report from EnviroChem, Inc. Bottom Description Answer Detail Comments/Legend: Shell Break Downs? Y MW: Manway D: Drain Annular Ring? N Annualr Ring Width: Annular Thickness: IN: Inlet OF: Overflow Base Width of Floor Width: 8' Thickness: IL: Inside Ladder F: Level Gauge Float Distance from Shell Dblr XMW: Abandoned Manway CAP: 16" diam. Cap in Floor Floor Penetrations (Overflow) Size Distance from Shell Dblr Drain Sump Size Distance from Shell Dblr Blistering Floor Welding Type? Lap Fillet Size Thickness Check Performed? Y No apparent material loss. Coating Condition Type of Coating I.D 71 feet Area 3,959 ft sq Coal Tar Condtion of Coating: Moderate % Failure: 20 +/- Type of Failures: Blistering Spot Corroded Areas: Timing Radius Spot Area Type of Failure 1 (var.) (var.) Coal tar blistering 20% throughout v IN 1 CAP IN X MW F MW D IL OF MW Observations: Average Thickness: 0.125" Coal tar floor coating about 20% failed consistantly across entire tank bottom. Coating thickness at about 1/8" average thickness. Attachments: (see photos) Structure Inspected By: Ray Crosno Coating Inspect By: Dan Smith, NACE Level III, Inspector No Date: 4/28/2009 Date: 4/28/2009

16 Area Inspection: Shell Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Yes, see separate lab report from EnviroChem, Inc. ShellDescription Width # of Plates Thickness Comments Ring 1 (bottom) 8 5/16" 8ft Ring 2 8 1/4" 8ft Ring 3 8 1/4" 8ft Thickness Check Performed? Y No apparent material loss If so See Attached Sheet Coating Condition Identification Map Type of Coating Interior Type of Coating Exterior I.D 71 feet Height: Interior Area 6,022 ft sq Ext Area 6,022 ft sq Hot-applied Coal Tar Epoxy/Urethane Condition of Coating Interior: See below % Failure: 80+ Condition of Coating Exterior: See below % Failure: Type of Failures Interior: Aligatoring, Blistering Type of Failures Exterior Thinning, spot rusting MW Spot Corroded Areas: Bearing Radius Spot Area Elevation Type of Failure Interior Interior 27 S 180 W N 0 IN X MW MW E 90 S 180 Int. Ladder 1 (various) 35ft (various) Alligatoring & Blistering throughout Observations: Exterior Attachments: (see photos) 2 (various) 35ft (various) Failure of finish coat throughout Exterior 3 (various) 35ft (various) Various minor spot rusting Alligatoring MW: Manway Blistering IN: Inlet XMW: Abandoned Manway Other Item (see notes) Average Thickness: (Exterior) 8-12 mils Interior: Hot-applied coal tar coating on shell all the way up to knuckle. Newer epoxy coating patches are present on tub ring, appear to be coating repair patches from exterior studs embeded in concrete seismic collar and at newer manways. Epoxy patch coating in good condition, average thickness 8-12mils. Coal tar shell coating shows aligator cracking throughout and at all levels of shell height. Tub ring is failed in about 70% - 80% of areas; Ring 2 failed in about 80% of areas; Ring 3 failed in about 90% - 100% of areas. The North side of the tub ring is in worse condition than the South side. In addition to alligatoring, there are also also some blister pockets holding water. Exterior: Finish coating is essentially 100% failed with undercoats showing through, though corrosion is not very active. Very minor spot rusting throughout. S 180 S Ext. Ladder Level Gauge # E 90 MW IN N 0 2, 3 W 270 MW S 180 Shell Inspected By: Ray Crosno Coating Inspect By: Dan Smith, NACE Level III, Inspector No Date: 4/28/2009 Date: 4/28/2009

17 Area Inspection: Rafters Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Roof Type: Knuckle (Knuckle/Cone/self supported cone or Dome/ other) No Rafter Description # of Rafters Size Bolted or Welded No Rafter Tie Bolts/ea Size bolts Condition of Bolts Qty ea. Type Radius of Tie Connection info Comments Inner bay 34 W8x10 Partially Bolted 2-4 unknown Poor - Marginal 4** ** see photos see photos **Orig. flat-bar rafter braces retrofitted with 2 rows of tension rods Mid Bay n/a Outer Bay n/a Mid Bay Girders n/a Outer Bay Girders n/a Knuckle Tail Type n/a Thickness Check Performed? Y/N If so See Attached Sheet NA Coating Condition I.D 71 ft Height: Interior Area 6,022 ft sq Ext Area 6,022 ft sq Type of Coating Epoxy Top Coated? not visible Weld/Caulk Lap? none Rafter Edge Condition Inner Rafters % Failure Mid Rafters n/a % Failure Outer Rafters n/a % Failure Inner Girders n/a % Failure Outer Girders n/a % Failure Type of Failures Exterior Spot Corroded Areas: Rafter # Radius Spot Area 1 (various) (various) 2 (various) 0-3ft 3 All 16ft +/- 4 All 32ft +/- 5 All 11' & 22' +/- 6 (various) 0ft Type of Failure 27 Moderate surface rust Heavier surface rust Original flat-bar bracing on top flanges Original flat-bar knuckle bracing on top flange Retrofit tension bars Approx 50% of rafters not bolted at center References Photos Observations: Attachments: (see photos) Average Thickness: (34) W8x10 rafters, originally braced with flat bar welded to top flange near mid-span, and another course of flat bar knuckle bracing at the perimeter. Rafters retrofitted at a later date with 2 rows of tension rods. Moderate surface rust is present throughout rafters; inside ends of rafters at center column cone/center vent are heavily rusted with some steel material degradation. Some rafters are bolted but a significant number (approximately 50%) are not bolted and due to the significant level of rusting, it is unclear whether the un-bolted rafters are welded instead or just free-floating. Structure Inspected By: Ray Crosno Coating Inspect By: Dan Smith, NACE Level III, Inspector No Date: 4/28/2009 Date: 4/28/2009

18 Area Inspection: Columns Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Roof Type: Knuckle (Knuckle/Cone/self supported cone or Dome/ other) Y/N Column Description # of Columns Size & Type Base Plate Type Size Thickness Col Cap Type Col Cap Thickness Size Bolt or Weld to Struct Size Bolts Comments/Legend: Center Column 1 6" Pipe Welded Steel Sqr 24" unknown Cone w/ dollar plate unknown unknown Partial Bolt unknown MW: Manway D: Drain Mid Bay Columns n/a IN: Inlet OF: Overflow Outer Bay Columns n/a IL: Inside Ladder F: Level Gauge C: Center Column CAP: 14" diam Cap in Floor Thickness Check Performed? No If so See Attached Sheet Coating Condition Type of Coating I.D 71 feet Height: Interior Area 6,022 ft sq Ext Area 6,022 ft sq Coal Tar 27 # (See Notes) P: Pax Circulation Device Center Column 100 % Failure Mid Bay Columns n/a % Failure Outer Bay Columns n/a % Failure Coal tar failed, rust blossoming IN CAP IN X MW MW F Spot Corroded Areas: Rafter # Radius Spot Area 1 Center Col. 0ft Type of Failure Coal tar failed, rust blossoming 1 C D IL OF MW Average Thickness: Observations: Hot applied coal tar coating on center column is essentially 100% failed, dry, alligatoring, and rust is starting to blossom, especially near the base. Column base plate appears to be free-floating with angle restraints at two corners. Attachments: (see photos) Structure Inspected By: Ray Crosno Coating Inspected By: Dan Smith, NACE Level III, Inspector No Date: 4/28/2009 Date: 4/28/2009

19 Area Inspection: Nozzles Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Roof Type: Knuckle (Knuckle/Cone/self supported cone or Dome/ other) Y/N Nozzle Description Size Thickness Reinf Plate Style Reinf Plate Thickness Dimensions Flange Bolts No. Bolt finish Washer? Elevation Standoff Style Standoff Spacing Comments & Condition Inlet 1 12" std. wall ** ** ** ** ** ** ** 16" +/- n/a n/a **Reinf Plate & hardware details unknown--exterior covered by concrete Inlet 2 - floor penetration 4" std. wall none n/a n/a none n/a n/a n/a (floor) n/a n/a 4" diam x 7 1/2" high floor penetration Inlet 3 n/a Inlet 4 n/a Overflow 12" std. wall none n/a n/a none n/a n/a n/a 26' +/- angle braces 10ft Cone inlet with interior overflow pipe. Hot dipped galv pipe. Drain Sump 24" x 6" x 12" unknown none n/a n/a none n/a n/a n/a (under-tank) n/a n/a 24" diam x 6"deep flush sump with 12" under-tank drain outlet. Thickness Check Performed? No If so See Attached Sheet Coating Condition I.D 71 Height: 27 Type of Coating Exterior n/a MW: Manway Type of Coating Interior Hot applied coal tar IN: Inlet OF Interior Coating? Hot dipped d galvanized CAP OF: Overflow Inlet 1: 12" shell nozzle 0 % Failure Newer epoxy in good condition D: Drain IN2 Inlet 2: 4" floor penetration 0 % Failure Newer epoxy in good condition IN1 IL: Inside Ladder 16" Floor Cap 0 % Failure Newer epoxy in good condition MW F: Level Gauge Float 24" Drain Sump <5 % Failure Original coal tar coating in fine condition F Overflow Pipe & Cone % Failure Original coal tar coating in fair condition Type of Failures Exterior D # See Notes Spot Corroded Areas: Location % Failure Spot Area Type of Failure IL OF MW Observations: Average Thickness: Inlet 1, a 12" shell nozzle, appears to be in good condition with a more recent epoxy coating patch in place of original coal tar, though the exterior of this nozzle is unknown due to the concrete collar on the outside. Inlet 2 is a 4" diameter x 7 1/2" high floor pipe penetration; it is coated with the original coal tar coating and appears to be in fine condition. There is also an abandoned and capped floor nozzle with a more recent epoxy coating patch repair. Overflow and drain sump still have original coal tar coatings, and appear in fair condition. Attachments: (see photos) Structure Inspected By: Dan Smith, NACE Level III, Inspector No Ray Crosno Coating Inspect By: Date: 4/28/2009 4/28/2009 Date:

20 Area Inspection: Appurtenances Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Roof Type: Knuckle (Knuckle/Cone/self supported cone or Dome/ other) Y/N Appurtenance Description Comments & Condition Interior Ladder Material Type Carbon Steel Width 16" Rung Diameter 3/4" Rung Condition Fair Saf-T Climb none Exterior Ladder Material Type Carbon Steel Width 16" Rung Diameter 3/4" Rung Condition Good Saf-T Climb none Exterior Mid Platform? Material Type n/a Size? n/a Grating Type n/a Grating Condition? n/a Other n/a Exterior Anti Climb Door? Material Type Carbon Steel Size? 18" Locking? Yes Hasp Shield? Yes Other Exterior Cage? Material Type None Cage Wrapped? n/a #cage FB n/a # Hoops n/a # Verticle bar n/a Exterior Handrail Coverage? About 5' each side of ladder Material Carbon Steel Toe Boards Yes Shell Manways Type: 5-Bolt Ext. Diameter 24" Reinforcing plate size 48" Octagon Bolts/ Washers O-ring Gasket? Level Gauge Functional? Yes? Manufacturer? unknown Half/Full Travel Full Exterior Board Yes Roof Hatch Size? 24" x 24" Lock Hasp?Y Door Size&Thickness? 28" x 28" x 1/4" Lid St Stop? partial Swing? center Inspection hatches none Roof Vent: (Center) Size Hood? 48" Size Inner? 30" Estimated Screen Opening unknown Screen Type?galv sqr mesh Cathodic Protection? Yes Type: Induced Current # of Anodes 5 & 15 Anode Radius 13ft & 29ft Coating Condition I.D 71 feet Height: 27 MW: Manway Type of Coating Epoxy exterior, Coal Tar Interior IN: Inlet % Failure OF: Overflow % Failure D: Drain % Failure CP F: Level Gauge Float % Failure CP IN CP GB: Gauge Board % Failure X MW IL: Interior Ladder Type of Failures Exterior CP MW CP EL: Exterior Ladder 4 Spot Corroded Areas: Location Spot Area Type of Failure F GB 2 CP CP: Anode Handhole Manway toggle bolt hardware 1 Minor rust blooming on hardware CP D EL Exterior Ladder & Level Guage 2 Minor rust blooming on ladder/brackets/fittings CP CP IL Interior Ladder 3 Moderate rust blooming, esp. below rungs CP 3 CV CP Handholes 4 Rust blooming at handhole locations CP CP CP # See Notes CP CP MW CP CP 1 CP CP CP OF Observations: Average Thickness: There are minor coatings failures with surface rust in various spots on virtually all appurtenances. The manway toggle-bolt hardware shows some surface rust at both manways. The exterior ladder, level guage, and associated fittings have some minor surface rust spots, especially under fittings and hardware. The interior ladder has minor to moderate rust throughout, especially under the ladder rungs and shell supports; there is a coatings shadow on the side rails under each rung. There is minor rust on the roof hatch and the around the CP handholes on the roof plate. Attachments: Structure Inspected By: Ray Crosno Coating Inspect By: Dan Smith, NACE Level III, Inspector No Date: 4/28/2009 Date: 4/28/2009

21 Area Inspection: Roof - Interior Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Y/N No Roof Description Other Comments Type-Knuckle/Cone/Dome/Self-support Knuckle Knuckle Radius 3ft Knuckle Type Haunched Compression Ring Size n/a Any Seal Welding or Caulking? Y/N Roof To Structure? Y/N Roof to Shell Joint? Roof Laps? Roof Plate Thickness? 3/16 Width of Plates? 6ft Thickness Check Performed? No (If so see attached sheet) Coating Condition I.D 71 feet Height: 27 Interior Area 3,957 ft sq Ext Area 3,957 ft sq Type of Coating Interior Epoxy Coating with Epoxy patches MW: Manway Rafter Edge Condition IL: Interior Ladder % Failure F: Float Assemb. Interior plate connections? % Failure H: Roof Hatch % Failure % Failure % Failure See Comments Spot Corroded Areas: Timing Radius Spot Area 1 (various) (various) Type of Failure Minor to moderate surface rust 1 Observations: Average Thickness: Original epoxy coating has aged and allowed minor to moderate surface rust in various areas throughout roof and structure. Areas within the first couple feet nearest the center vent show more advanced corrosion--moderate to heavy rust. Newer epoxy patches near retrofitted rafter ties are in good condition. Attachments: (see photos) Structure Inspected By: Ray Crosno Coating Inspect By: Wade Crosno, Crosno Construction Date: 4/28/2009 Date: 4/28/2009

22 Area Inspection: Roof - Exterior Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Hazardous Material Test Performed? Yes, see separate lab report from EnviroChem, Inc. Roof Description Other Comments Type-Knuckle/Cone/Dome/Self-support Knuckle Knuckle Radius 3ft Knuckle Type Haunched Compression Ring Size n/a Any Seal Welding or Caulking? Roof To Structure? None apparent. Roof to Shell Joint? None apparent. Roof Laps? None apparent. Roof Plate Thickness? not tested Width of Plates? 6ft Thickness Check Performed? No (If so see attached sheet) Coating Condition Legend: I.D 71 feet Height: 27 MW: Manway Interior Area 3,957 ft sq Ext Area 3,957 ft sq EL: Exterior Ladder Type of Coating Interior LG: Level Guage Type of Coating Exterior Alkyd system Rafter Edge Condition F: Float Assemb. % Failure IN: Inlet % Failure CV: Roof Center Vent Exterior Ponding Issues? No % Failure H: Roof Hatch % Failure % Failure Surface Rust Bloom Spot Corroded Areas: Timing Radius Spot Area Type of Failure 1 (various) (various) Finish coat degraded, moderate mold/moss, minor rust Other Item (see notes) 2 (various) 13ft & 29ft 20 loc'ns Surface rust at CP handhole covers # 2 CP 1 Observations: Average Thickness: The finish coat is degraded and essentially 100% failed, but rust is still fairly minor; there are minor isolated surface rust spots in various areas throughout roof plate as well as a moderate amount of moss. All of the 20 CP handholes have moderate surface rust blooming in roof plate due to electrolysis with stainless steel handhole covers; SS covers are in fine condition. Attachments: (see photos) Structure Inspected By: Ray Crosno Coating Inspect By: Wade Crosno, Crosno Construction Date: 4/28/2009 Date: 4/28/2009

23 Area Inspection: Bottom Thickness Map Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Bottom Description Answer Detail Comments/Legend: Shell Break Downs? MW: manway D: drain Annular Ring? Annualr Ring Width: Annular Thickness: IN: inlet OF: Overflow Base Width of Floor Width: Thickness: IL: inside ladder F: level gauge float Floor Penetrations Size Distance from Shell Dblr Floor Penetrations (Overflow) Size Distance from Shell Dblr Bottom Thickness Marker Drain Sump Size Distance from Shell Dblr Floor Welding Type? (Lap or Butt) Fillet Size Thickness Check Performed? Y/N (If so, see attached thickness map) Plate Thickness I.D 71 feet Area 3,959 ft sq Note: Steel plate thickness measured using Ultrasonic Thickness Guage by NDT Systems, Nova TG110-DL, SN: B1 General Material Condition: % Remaining IN Thickness Test Location Timing Radius B1 11:59 16ft B2 10:35 30ft B2 10:35 30ft B3 10:25 32ft B3 10:25 32ft B4 8:50 22ft B5 7:25 14ft B5 7:25 14ft B6 5:45 33ft B7 4:35 32ft B8 4:20 32ft B9 2:55 22ft Measured Thickness Description B2 B Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate Bottom Plate 0.28 Bottom Plate Bottom Plate MW B4 X MW B1 B9 B5 B8 B7 B6 Observations: Bottom plate material thickness readings appear consistent and material appears to be in fine shape. Attachments: (see photos) Structure Inspected By: Ray Crosno Thickness Measured By: Wade Crosno, Crosno Construction Date: 4/28/2009 Date: 4/28/2009 MW F D IL OF

24 Area Inspection: Shell Thickness Map Date: 28-Apr-09 Tank Name: Skyfarm III, Tank 2 Location: Town of Hillsborough Diameter: 71ft Shell Description Width 96" # of Plates Thickness Comments Ring 1 7 1/4 **Approximately bottom 24" of tub ring encased by concrete collar on exterior. Ring 2 7 1/4 Ring 3 7 1/4 96" 96" Thickness Check Performed? Y/N Shell Thickness I.D 66 ft Height: 26 ft Interior Area 5,391 ft sq Ext Area 5,391 ft sq Note: Steel plate thickness measured using Ultrasonic Thickness Guage by NDT Systems, Nova TG110-DL SN: General Material Condition: % Remaining Thickness Test Location Bearing Height Measured Thickness Description S9 MW MW S " Tub ring, below concrete collar S7 S1 S2 S3 IN XMW S " Tub ring, below concrete collar S4 S5 S6 S10 S11 S8 S " Tub ring, below concrete collar S " Tub ring, below concrete collar S " Tub ring, below concrete collar S1 Shell Thickness Marker MW: Manway F: Level Gauge Float S " Tub ring, below concrete collar IN: Inlet OF: Overflow S " Tub ring, below concrete collar Shell Horiz Seam IL: Interior Ladder D: Drain Sump S " Tub ring, below concrete collar Concrete Collar on Exterior S " Tub ring, below concrete collar S " 0.29 Tub ring, below concrete collar S " Tub ring, below concrete collar S " Tub ring, below concrete collar S " Tub ring, below concrete collar S " Tub ring, below concrete collar S " Tub ring, above concrete collar S " Tub ring, below concrete collar (Note: orientation is from inside view) S " Tub ring, below concrete collar S " Tub ring, below concrete collar Observations: S 180 W 270 N 0 E 90 S 180 Interior Ladder Shell thickness measurements were taken at 17 locations in areas covered by the exterior concrete seismic collar, and one location above the concrete collar as a check value. All measurements appeared to show that the steel plate material is in good condition; material degradation due to corrosion appears negligable. Maintaining the caulking or sealing at the exterior joint between the concrete collar and the tank shell will reduce the amount of moisture in between the two, and should continue to help maintain negligable future corrossion. Attachments: (see photos) S12 Structure Inspected By: Ray Crosno Coating Inspect By: Wade Crosno, Crosno Construction Date: 4/28/2009 Date: 4/28/2009

25 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) APPENDIX B FIELD PHOTOS Page 14 Marlborough Tank No.2 Town of Hillsborough

26 Skyfarm 3 Skyfarm 3 Tank 2 Tank Nameplate Tank 2 Manway

27 Upgrade Project Notice Tank Inlet/Outlet Tank Inlet/Outlet Valve Inlet/Outlet Elbow-Flextend-Valve

28 Valve Vault Tank Coupling & Valve Can 2 Tank Coupling Manway

29 Manway Drain Valve Can Concrete Seismic Collar Seismic Collar, 42 Width

30 Seismic Collar, +/- 42 Height Concrete Collar Concrete Collar Concrete Collar

31 Concrete Collar Concrete Collar Concrete Collar Concrete Collar

32 Concrete Collar Concrete Collar Concrete Collar Concrete Collar

33 Concrete Collar Concrete Collar Concrete Collar to Shell Concrete Collar to Shell

34 Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell

35 Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell

36 Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell

37 Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell

38 Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell Concrete Collar to Shell

39 Concrete Collar to Shell Concrete Collar to Shell Exterior Shell Exterior Shell

40 Exterior Shell Exterior Shell Exterior at Ladder Exterior Ladder & Gauge Board

41 Roof Handrail & Hatch Level Gauge Roof Assembly Roof Equipment & Conduit Gauge Board Assembly

42 Gauge Board to Knuckle Roof Hatch Skyfarm 3, Tank 1 in Background Roof Spot Rust & Mold

43 Roof Spot Rust & Mold Roof Spot Rust & Mold Roof, Typical CP Handhole Roof Spot Rust & Mold

44 Roof Spot Rust & Mold Roof, CP Handhole Roof Spot Rust & Mold Roof & Center Vent

45 Center Vent Fiberglass Hood Center Vent Screen Detail Manway Manway

46 Manway Manway Detail Inlet/Outlet Capped & Abandoned Floor Nozzle

47 Overflow Base Overflow Shell Supports Ladder Base Drain Sump & Level Gauge Float

48 CP Rectifier Ladder, Overflow, Hatch Manway, Ladder, Overflow 2 Shell Coupling

49 Overflow Weir Cone Bottom Nozzle Floor Coatings Floor Coatings

50 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

51 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

52 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

53 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

54 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

55 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

56 Floor Coatings Floor Coatings Floor Coatings Floor Coatings

57 I/O Nozzle & Epoxy Shell Patches Epoxy Shell Patch Detail Epoxy Shell Patches Epoxy Shell Patches

58 Interior Shell Interior Shell Interior Shell Interior Shell

59 Interior Shell Interior Shell Interior Shell Interior Shell

60 Interior Shell Interior Shell Interior Shell Shell Detail

61 Shell Shell Shell Detail Shell Detail

62 Shell Shell Shell Shell

63 Shell Shell Knuckle Knuckle

64 Roundseam Rafter End Rafter End Detail Rafter Tail to Shell

65 Original Seismic Brace Original Seismic Brace Retrofit Seismic Tie-Rod Retrofit Seismic Tie-Rod

66 Center Column Cone Center Column Center Column Baseplate Roof

67 Roof Roof Roof Roof

68 Roof Roof Center Vent & Rafter Ends Rafter Ends

69 Rafter Ends Rafter Ends Rafter Ends Rafter Ends

70 Rafter Ends Rafter Ends Rafter Ends Rafter Ends

71 819 Sheridan Rd., Arroyo Grande, CA Phone (805) Fax (805) APPENDIX C STRUCTURAL ANALYSIS CALCULATIONS Page 15 Marlborough Tank No.2 Town of Hillsborough

72 HEI Hagen Engineering International, Inc Tank Contractor Crosno Construction Tank Location Hillsborough, CA Project Name Skyfarm III, Tank 2 Design Parameters AWWA D100 Tank Data Sheet Design Code AWWA D Section 14 Yes DMT 40 Deg Corrosion Allowance None Allowable Soil Bearing 4,000 psf Roof Live Load 20 psf Design Wind Speed 120 mph (3 Sec. Gust) Seismic Zone AWWA D Section 13 Seismic Data SUG III Tank Geometry Site Class D Ss g Diameter 71 ft S g Shell Height 24 ft Knuckle 3ft Roof Slope 0.75 :12 Design Height 24 ft Nominal Capacity 710,803 gallons Tank Design (Note: Nominal as built thicknesses used) t Material Welding in Bottom 0.25 A36 Lap Sketch Plates 0.25 A36 Lap Shell Height, ft A36 Butt A36 Butt A36 Butt Knuckle 0.25 A36 Butt Rim Angle N/A Roof A36 Lap Roof Structural Design Qty Description Size 34 Rafters W8x10 1 Column 6" Sch 40 Base Plate 24"x24"x1/2" Anchor Chairs 14 Intermediate Wind Girders None Date Printed 10/29/2009 Sheet 1 of 11 Rev. 0

73 Bottom Minimum per AWWA D 100 Minimum per Specifications T use 0.25 in 0.25 in 0.25 in Shell t= 2.6 * H * D E * S H = Hydrostatic Head D = Tank Diameter = 71 Ft. E = Joint Efficiency = 1 S = Allowable Stress = 19,200 Psi Material A36 Course Course H t req'd t use Actual Weight Height Stress ft. ft. in. in. psi lbs ,177 22, ,814 18, ,907 18, ,154 Date Printed 10/29/2009 Sheet 2 of 11 Rev. 0

74 Roof Plate Design L = 2575 * t <= 84" (Wdl+ll)^.5 L = Maximum Spacing between rafters t = Roof plate thickness = in Wdl+ll = Roof Live load + Dead Load Live Load 25 psf Dead Load 8 psf Total 33 psf L = 84 inches < 84" L = 84 in Actual Spacing Outer Diameter = 65 ft Number of Rafters = 34 L actual = 72 in Date Printed 10/29/2009 Sheet 3 of 11 Rev. 0

75 Roof Rafter Design wt w w R Left Length R Outside R Right R Inside Number of Rafters 34 R Outside 32.5 Ft R Inside Ft Dead Load 8 psf Live Load 25 psf Rafter Wt 10 lb/ft Rafter Length = Ft Wt W1 W2 R Left R Right Max Moment lb/ft lb/ft lb/ft lb lb ft-lbs Dead load ,157 Live Load , ,689 Dead + Live ,233 1,259 13,841 Loads to Shell Loads to Columns Dead 21,841 lbs lbs Live 54,086 lbs lbs Total 75,927 lbs lbs Rafter Design Fb = 22,000 psi Smin = Moment * 12 / Fb = 7.55 in^3 W8x10 S = 7.81 in^3 Ok Date Printed 10/29/2009 Sheet 4 of 11 Rev. 0

76 Center Column P = Column 42,804 lbs 2,000 lbs 44,804 lbs Column Design L = ft. 6" sch 40 a = 5.58 sq. in r = in L/r = 110 fc = P/A = 8,029 psi Fc = 11,670 psi >> 8,029 psi Base Plate 24" x 24" x 1/2" Maximum Load = Base Plate Width = Base Plate Thickness Base Plate Area = Bearing = Column O.D. Bending Moment Plate S Bending Stress = M/S Fb = 44,804 lbs 2.00 ft- Square 0.50 in 4.00 sq.ft. 11,201 psf 8 in 35,485 in-lbs 1.00 in^3 35,485 psi 22,000 psi Note: Based on above it is assumed that there is a concrete pad under column. Date Printed 10/29/2009 Sheet 5 of 11 Rev. 0

77 Seismic Ref : AWWA D Base Shear = Vact = (18*Z*I/Rw)*(.14*(Ws+Wr+Wf+W1)+ S*C1*W2) Overturning Moment =(18*Z*I/Rw)*(.14*(Ws*Xs+Wr*Ht+W1*X1)+ S*C1*W2*X2) Inputed Variables Z 0.4 Zone 4 I 1.25 Importance Factor Rw 3.5 Ws 59,154 lbs Wr 35,922 lbs Wf 40,384 lbs Xs 10 Ft Xr 20 Ft S 1.5 Diameter 71 Ft Height 17 Ft Calculated Variables Kp 0.69 Tw 5.80 Seconds C W 4,199,921 lbs W1 1,159,543 lbs W2 2,847,410 lbs X Ft X Ft Base Shear = Vact = Overturning Moment = 711,296 lbs 5,340,506 Ft-Lbs Sloshing Wave Height = d = 7.53 * D * ( ZIC1S/Rw) d= 1.70 ft Date Printed 10/29/2009 Sheet 6 of 11 Rev. 0

78 Resistance to Overturning wl = 7.9*tb*(Fy*H*G)^.5 wl max = 1.28*H*D*G tb = 0.25 in. Fy = psi A36 D = 71 ft H = 17 ft G = 1 wrs 21,841 lbs weight of roof acting on shell wl = wl max wl use = 1,545 lb/ft 1,545 lb/ft 1,545 lb/ft L Max =.035 * D L min =.216 * tb* (Fy / ( H*G))^ ft 2.48 ft wt = Ws/( Pi * D)+ wrs ws = wrs = 59,154 lbs 98 lb/ft wt = Moment = 363 lb/ft 5,340,506 ft-lbs M/(D^2*(wt+wl)) = <.785,Therefor there is no uplift Date Printed 10/29/2009 Sheet 7 of 11 Rev. 0

79 AWWA Seismic Ref : AWWA D Ws Wr Wf Xs Xr Diameter Height 59,154 lbs 35,922 lbs 40,384 lbs 10 Ft 20 Ft 71 Ft 17 Ft Calculated Variables Kp 0.69 Tc 5.80 Seconds C W 4,199,921 lbs Wi 1,159,543 lbs Wc 2,847,410 lbs Xi 6.38 Ft Xc 9.01 Ft Ie = 1.25 Seismic Use Group II Fa = 1 Site Class C Fv = 1.3 Site Class C Ri = 3 Rc= 1.5 U = K = 1.5 Ss = S1 = TL = g g 12 sec Sms = Fa * Ss Sm1 = Fv * S1 Sds = U * Sms = Sd1 = U * Sm1 = g g g g Sai = Sds g Tc < TL Sac = K * Sd1/ Tc = g Ai = Sai * Ie / ( 1.4 * Ri) = or Ai =0.36* S1* Ie/ Ri = Ai = Ac = Sac * Ie / ( 1.4* Rc) = g g g g Ms = 5,330,559 ft-lbs AWWA Eq Vf = 537,798 lbs AWWA Eq Date Printed 10/29/2009 Sheet 8 of 11 Rev. 0