RT2D-K120-00

Ras Tanura Integrated Project (RTIP)Document No: RT2D-K120-00 KBR Project No. A554Revision: 1 TANK FOUNDATION GUIDELINESIssue Purpose: IFD Contains Confidential information of Both Dow and Saudi Aramco Page 2 of 6 SUMMARY OF DOCUMENT REVISIONS Rev. No. Date Revised Section RevisedRevision Description 0 8-May-08Issued For Design 109-Dec-10General 1.3.3 2.3.1.3 2.3.2.5 2.3.2.6 Issued per A554-RFV-PRG-759 Issued For FEED & EPC Use Updated standards document number Added new section Revised section Substituted the section Ras Tanura Integrated Project (RTIP)Document No: RT2D-K120-00 KBR Project No. A554Revision: 1 TANK FOUNDATION GUIDELINESIssue Purpose: IFD Contains Confidential information of Both Dow and Saudi Aramco Page 3 of 6 PREFACE ThisstandardorspecificationisarevisionoranoverlaytoaDOWEMETL,LPP, Engineering Standard, or a Saudi Aramco Materials System Specification, for the scope oftheRasTanuraIntegratedProject(RTIP),unlessspecificallydefinedasaNew document.ARTIPspecificationconsistsofarevisionoranoverlayandtheDOW document with the same name. An overlay establishes if there are any required changes to the DOW document and specifically defines the changes. If the DOW document is to be used without any changes the overlay will state there are no changes required. If the document is a new RTIP document, with no reference to a DOW standard, the overlay will state it. TheRTIPSpecification IndexidentifieswhichRTIPdocumentsarenewandtheones that relate to documents that are unchanged, changed, or deleted. AllreferencestoDOWprocedures,specificationsandstandardsaretobedefinedas references to RTIP procedures, specifications and standards unless specifically stated otherwise in the overlay. All references to DOW organizations are to be defined as the RTIP Management Team. Interpret the following as specified: Revise A specific revision to a (EMETL or LPP) paragraph or sentence as noted in this specification. Add Continuation of a (EMETL or LPP) paragraph with an overlay requirement. SubstituteReplacethe(EMETLorLPP)paragraphinentiretybytheoverlay requirement. NewNewparagraphnumberintheoverlaywithnocorrespondingDOW paragraph. Delete paragraph is deleted by the overlay. REVISION ThisoverlayisarevisiontoDowsEngineeringSpecificationG2D-K120-0,Tank Foundation Guidelines, 30-J un-2005. The following sections and paragraph numbers match that of the Dow document of the same name unless noted as New. ATTACHMENT G2D-K120-00: TANK FOUNDATION GUIDELINESRas Tanura Integrated Project (RTIP)Document No: RT2D-K120-00 KBR Project No. A554Revision: 1 TANK FOUNDATION GUIDELINESIssue Purpose: IFD Contains Confidential information of Both Dow and Saudi Aramco Page 4 of 6

1.0PURPOSE 1.1.1 (Revise) Replace The Dow Loss Prevention Principles by TheRTIP Project.1.2.3 (Delete) 1.3References 1.3.3(Revise) Delete the first entry, G2D-2003-15, in the Table. (Revise)DeleteG2D-K100-00,G2G-3340-80,G2G-3340-82andG2G-3340-87andreplacewithRT2G-K100-00,RT2G-3340-80,RT2G-3340-82and RT2G-3340-87. 2.0Design Considerations 2.1.2.2(Delete) 2.2 Bearing Capacity and Settlement 2.2.1.1 (Delete) 2.2.1.2 (Substitute)Designparameterse.g.,ultimatebearingcapacityfortank unconfinedcompressivestrengthetc.shallconformwiththerecommendation prescribed in the latest geotechnical investigation report. 2.2.2Settlement 2.2.2.1 (Substitute) Historical data on settlement for the particular area and soils can be usefuldesigntoolsincesoilcharacteristicswillvarywithregion.Cautionisneededin areas with soft soils. 2.2.2.5 (Substitute) Tank contents should be considered to be a sustained load. Elastic up and down movement of the foundation can still occur as the tank isemptied and filled. This should be considered in piping design. 2.2.4Spacing of Tanks 2.2.4.3 (Substitute)SpacingmaybegovernedbyLossPreventionPrinciples7.5 depending on contents and /or local requirements. 2.3Common Types of Foundations 2.3.1.3(New)FoundationsforAPI650tanksshallbeinaccordancewithAPI Standard650,AppendixB,RecommendationsForDesignAndConstructionOf Foundations For Above Ground Oil Storage Tanks. 2.3.2.5(Revise) The ringwall width should be determined both on the basis of the allowable soil bearing pressure and such that the soil pressures under the entire Ras Tanura Integrated Project (RTIP)Document No: RT2D-K120-00 KBR Project No. A554Revision: 1 TANK FOUNDATION GUIDELINESIssue Purpose: IFD Contains Confidential information of Both Dow and Saudi Aramco Page 5 of 6 tank and the wall are equal at the level of the wall base for the full contents of the tank.Thethicknessoftheringwallforthebalancedsoilpressureconditionmay be determined by the following formula: 2.3.2.5(Substitute)Specialconsiderationwillberequiredforupliftifthetankis pressurized, including, but not limited to the following: FoundationsforAPI650tankssubjectedtointernalpressuresshallbe designedtoresisttheupliftforcesinaccordancewithAPISTD650, Appendix F. For ringwalls designed to prevent uplift condition due to internal pressure, the resulting counterbalancing resisting weight shall be 1.5 times the uplift force. Balancingthebearingpressureunderthetankandtheringwallisnot required for the internal pressure loading conditions. 2.3.4Concrete Mat Foundation 2.3.4.2 (Revise) The words Foundations TRL to read as Owners Representative 2.3.4.15 (Delete) 2.4(Delete) including all sub sections.2.5.2 Drainage 2.5.2.2 (Delete) (Note German regulations require a minimum slope of 2 percent.) 2.5.3Cathodic Protection 2.5.3.3 (Revise) Add Ras Tanura in the list of locations. 2.5.3.4 (Revise) Delete G2G-3340-87 and replace with RT2G-3340-80 or RT2G-3340-85 2.6 Seismic Conditions

2.6.1 (Add) Add at the end of the first paragraph; Seismic overturning moment in tank andshearforcesshallbeprovidedbythetankSupplier.Theminimumsafetyfactor against overturning and sliding shall be 1.5. Refer to ASCE 7-05, API 650 for seismic forces computation. 2.8Cost 2.8.1(Substitute) Therefore, it is recommended that a study be made for each design based ongeotechnicalinvestigationandsiteconditionstodeterminetheminimum requirements and still have a safe design. 3.1.5.4 (Revise) Replace the last sentence with See Engineering Detail RT2G-3340-42 orRT2G-3340-87 Ras Tanura Integrated Project (RTIP)Document No: RT2D-K120-00 KBR Project No. A554Revision: 1 TANK FOUNDATION GUIDELINESIssue Purpose: IFD Contains Confidential information of Both Dow and Saudi Aramco Page 6 of 6 4.3Local shear Soil Failure Repair (Delete) 4.3.1 (Delete) 5. Appendices 5.2.B (Delete) A.5.6 (Delete) Appendix B (Delete) THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 1 of 29 DOW RESTRICTED - For internal use only iTANK FOUNDATION GUIDELINES TABLE OF CONTENTS 1. GENERAL 1.1. Purpose 1.2. Scope 1.3. References 2. DESIGN CONSIDERATIONS 2.1. Site Investigation 2.2. Bearing Capacity and Settlement 2.3. Common Types of Foundations 2.4. Frost Action 2.5. Corrosion Protection 2.6. Seismic Conditions 2.7. Wind Condition and Internal Tank Pressure 2.8. Cost3. ENVIRONMENTAL CONSIDERATIONS 3.1. Leak Detection and Collection Systems 3.2. Spill Containment 4. RETROFIT AND REPAIR 4.1. False Bottoms 4.2. Foundation Repair 4.3. Local Shear Soil Failure Repair 5. APPENDICES 5.1. A Site Investigations 5.2. B Frost Action 5.3. C Controlled Tank Settlement 5.4. D Foundation Design for Tank With Internal Pressure THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 2 of 29 DOW RESTRICTED - For internal use only GENERAL 1.1. Purpose 1.1.1. The purpose of these guidelines is to aid in the design of environmentally safe and economical tank foundations that meet the requirements of The Dow Loss Prevention Principles. 1.2. Scope 1.2.1. The guidelines are a collection of practices and experience which are to be used for design of flat bottom storage tank foundations.They are intended to benefit the civil engineer with little experience in tank foundation design as well as an experienced civil engineer. 1.2.2. It is the responsibility of the Civil designer to understand the requirements of local codes and regulations and apply them accordingly along with sound engineering judgment to meet the specific environmental, geotechnical, and structural conditions of the installation. 1.2.3. Some businesses have developed specific requirements for tank foundations. Check the Business-specific sections of EMETL, Business Technology Center, and local Civil DAS for special requirements before proceeding with design. 1.3. References 1.3.1. Unconfined compressive strength - ASTM D2166 1.3.2. Undrained shear strength ASTM D2850 1.3.3. Dow Civil Engineering Level 1 MET: G2D-2003-15M2 Geotechnical Engineering Site Investigation Project Flow Chart G2D-K100-00Spill Containment Guidelines G2G-3340-80Ringwall Foundation G2G-3340-82Concrete Ring Leak Detection System G2G-3340-87Concrete Mat Leak Detection System G2S-2001-01Grouting Drilled Excavations 2. Design Considerations 2.1. Site Investigation 2.1.1. Objective of Site Investigations 2.1.1.1. The primary objective of a site investigation is to provide information relating to the subsurface characteristics of the site. 2.1.2. Background Information THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 3 of 29 DOW RESTRICTED - For internal use only 2.1.2.1. Prior to undertaking any field investigation, the designer should become familiar with the conditions at the site. 2.1.2.2. The behavior of similar existing structures and foundations on or near the site will also give clues as to the suitability and expected performance of the proposed design. 2.1.3. Soil Borings 2.1.3.1. The soils investigation should ensure that the entire zone of soil or rock that will be affected by the structure will be adequately explored. 2.1.3.2. The following guidelines may be used to determine the depth of boreholes required: 2.1.3.3. For tanks with diameters less than or equal to 60 feet, extend holes to a maximum of: 1.5 x dia; or limiting geological feature 2.1.3.4. For tanks with diameters greater than 60 feet, extend holes to: 1.0 x dia; or minimum of 30 m (100 feet); or limiting geological feature. 2.1.3.5. At new or unexplored sites, at least one boring should extend to the limiting geological feature of the site, which may be dense sands or gravel, till, or bedrock. The boring should extend at least 10 feet into this feature. 2.1.3.6. Note that soil boreholes may become a conduit for transmission of contaminants through soil strata.Surface casing may be needed to isolate soils suspected of being contaminated from deeper, uncontaminated soils and groundwater.All boreholes should be backfilled from the bottom up according to Engineering Specification G2S-2001-01. 2.1.3.7. At least three boreholes should be drilled at any new or undeveloped site. Additional holes may be required as follows: In areas with large variability in the subsurface conditions. Where the site covers a very large area, holes could be located at major equipment or structures, and THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 4 of 29 DOW RESTRICTED - For internal use only additionally on a grid ranging from 30 m to 60 m (100 feet to 200 feet) spacing. Where sites have been well-documented, then one borehole at the center of the tank may be sufficient, or additional holes may not be necessary. 2.1.4. Reports 2.1.4.1. The soils investigation report should be a clear, complete, and accurate summary of the site investigation. 2.1.4.2. Refer to Appendix A, for further details on the requirements for soils investigations. 2.2. Bearing Capacity and Settlement 2.2.1. Bearing Capacity 2.2.1.1. Local Dow expertise should be consulted, where available, to determine design requirements. 2.2.1.2. The ultimate bearing capacity for tanks on clay should be taken as 3.6 times the laboratory unconfined compressive strength or 7.2 times the undrained shear strength. 2.2.1.3. To prevent shear failure of the weakest major soil strata, a factor of safety of 1.7 with respect to ultimate bearing capacity should be used. Settlement will occur at this factor of safety.(See Section on Settlement). To limit settlement use a safety factor of 2.5 to 3 with respect to ultimate bearing capacity under sustained loads. 2.2.1.4. See the paper "Stability of Steel Oil Storage Tanks"1 for methods for determining factors of safety. This procedure uses a factor slightly less than the 7.2 times undrained shear strength mentioned above, but the 7.2 factor has been used successfully for years. 2.2.1.5. The ultimate bearing capacity of sand will depend mainly on four variables - the position of the water table, the relative density of the sand, the width of the footing, and the depth of the surcharge surrounding the footing. While it is possible to correlate the N-values from the standard penetration test to the relative density of the sand, and from there to the bearing capacity, exercise caution in their interpretation. The cone penetrometer is the 1 James M. Duncan and Timothy B. DOrazio, Stability of Steel Oil Storage Tanks, Journal of Geotechnical Engineering, Vol. 110, No. 9, (September 1984), ISSN 0733-9410/84/0009-1219, Paper No. 19125 THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 5 of 29 DOW RESTRICTED - For internal use only best way to determine the angle of internal friction, from which the bearing capacity may be determined. 2.2.1.6. For sand there are a number of similar methods for determining the ultimate bearing capacity. The textbooks "Principles of Geotechnical Engineering"2 and "Foundation Analysis and Design"3 describe some of these methods. The Terzaghi method is the simplest. It consists of the following equations: Square Footings: qult = 1.3cNc + QNq + 0.4VB Nv Round Footings:qult = 1.3cNc + QNq + 0.3VB Nv

Where: qult = Ultimate Bearing Capacity Q = Surcharge = (Depth to bottom of foundation) x (unit weight of soil) c = Cohesion V = Unit Weight 2.2.1.7. A factor of safety of 2 to 3 should be used depending on certainty. Hansen's method is similar, but uses many additional factors. It is supposed to be somewhat more refined. 2.2.1.8. If Dutch cone penetrometer data is used the following equation can be used: qa = qc/F F = 30 TO 40 kg/cm2 qa = allowable bearing capacity (F.S. = 2 TO 3) qc = static cone bearing 2.2.2. Settlement 2.2.2.1. Historical data on settlement for the particular area and soils can be a useful design tool since soil characteristics will vary with region. Caution is needed in areas with soft soils, such as the Louisiana Division. 2.2.2.2. Settlement is a permanent plastic movement of the soil.Some storage tanks can undergo large uniform settlements with no detrimental effect if that settlement is provided for in the piping and other attachments, or if most of the settlement takes places before the attachments are made. In other instances, 2 Brajas M. Das, Principles of Geotechnical Engineering, (Brooks/Cole Engineering Division). 3 Joseph M. Bowels, Foundation Analysis And Design, (McGraw-Hill Book Company). THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 6 of 29 DOW RESTRICTED - For internal use only very small settlement can have a negative impact on attached piping or other structures. In order to design the most economical foundation the designer must know where and how much settlement can be tolerated. 2.2.2.3. Confirm with Operations and other design disciplines that anticipated settlements are acceptable. 2.2.2.4. Deep foundations (piles, drilled shafts, etc.) may be used to mitigate the effects of settlement if permitted by local regulations. Confirm requirements with local Civil DAS and EH&S Delivery Leader. 2.2.2.5. Tank contents should be considered to be a sustained load.Elastic up and down movement of the foundation will still occur, which can be 3/4 to 1 inch, as the tank is emptied and filled. This should be considered in piping design. 2.2.2.6. The factor of safety in the above section of 2.5 to 3 can be reduced if some settlement can be tolerated, but care must be exercised so as not to have a shear failure. 2.2.2.7. In some locations settlements of 3 to 4 feet have been successful. For large tanks where uneven settlement occurs, tanks can be floated off the foundation and the foundation leveled. This is usually less expensive than driving piles. 2.2.3. Soil Consolidation by Incremental Loading and Controlled Settlement. 2.2.3.1. The ultimate strength of the soil may be increased by consolidating the soil by preloading. This may be done by incrementally filling the tank with water over a period of time. This method can be used for concrete ring, earthen foundations, and concrete mat foundations. See Appendix B for a detailed method on how to do this safely and without having a shear failure caused by loading too quickly. The tank may continue settling during its service life after the incremental loading.This could be as much as 1" to 2" depending on the thickness of the soft layers. Therefore, piping should be adequately flexible. 2.2.3.2. NOTE: Do not use sand or geosynthetic drains to decrease consolidation time because this can serve as a conduit for contaminated liquids to reach groundwater. 2.2.3.3. Controlled loading of tank with water is not required if safety factor is greater than 1.7 for soil bearing capacity. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 7 of 29 DOW RESTRICTED - For internal use only 2.2.4. Spacing of Tanks 2.2.4.1. Spacing too close can cause tilting when settling. 2.2.4.2. Clear space between tanks should be at least the sum of the radii divided by two, i.e.: d = (r1 +r2)/2 unless calculations indicate very little or no differential settlement will occur. 2.2.4.3. Spacing may be governed by Loss Prevention Principle 7.6.6 depending on contents. 2.2.4.4. The distance from the storage tank wall to the inside face of the dike wall shall be the minimum of 5 m (16.4 ft) or the distance calculated using the method described in Loss Prevention Principle 7.5. 2.2.5. Determining Amount of Settlement 2.2.5.1. Tank center settlement may best be determined based on historical data for similar loadings at the site. The next best method is to run consolidation test on the layers likely to consolidate, draw a void ratio vs. pressure curve and run the appropriate calculations as described in most soils texts. These calculations can sometimes miss by as much as 50% because the samples used for testing may not be representative. 2.2.5.2. Tank edge settlements will usually be less than center settlements, by as much as 1/3 to 1/2.Slopes on leak detection systems should be designed to take this into account. 2.2.5.3. Each case should be examined to determine the allowable differential settlement. Floating roof tanks should receive particular attention. 2.3. Common Types of Foundations 2.3.1. General 2.3.1.1. Tank foundations shall be constructed at an elevation to ensure that the tank bottom is a minimum distance above the surrounding grade after initial settlement of: 305 mm (12 in) depth of 25-year, 24-hour rainfall plus 250 mm (10 in) depth of 100-year, 24-hour rainfall THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 8 of 29 DOW RESTRICTED - For internal use only 2.3.1.2. Calculated consolidation settlements, elastic settlements, and rainfall volumes should be shown on the foundation construction drawings. 2.3.2. Concrete Rings 2.3.2.1. Concrete ring foundations are generally used for very low pressure tanks greater than 40 foot diameter. 2.3.2.2. The advantages of ring wall foundations are: They have a clean, neat appearance. Maintenance is easier than for earthen or asphalt berms. They make an excellent foundation construction of the tank shell. If the tank is in a paved area, a ring wall foundation makes secondary containment neater and simpler. Ringwall foundations lend themselves well to leak detection systems by providing containment around the tank bottom. 2.3.2.3. The circumference of the ring foundation should be designed so that the steel tank wall rests near the center of the concrete ring foundation when viewed in section. 2.3.2.4. The bottom of the ring wall should be placed against undisturbed soil if possible. Otherwise, see to it that the backfill both inside and outside the wall is thoroughly compacted. A granular, relatively non-compressible material is recommended for inside fill unless environmental restrictions prohibit it. 2.3.2.5. The ring wall should be designed so that the soil pressures under the entire tank and wall are equal at the level of the wall base. The thickness of the concrete may be determined by the following formula: T = 24W /(QH - 80h) Where: T = thickness of wall in inches W = weight of metal in shell and roof supported on the ring wall in pounds per foot of circumference H = height of tank shell in feet Q = weight of stored product in pounds per cubic foot h = height of the ring wall in feet THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 9 of 29 DOW RESTRICTED - For internal use only 2.3.2.6. Special consideration will be required for uplift if the tank is pressurized. 2.3.2.7. The wall should be reinforced circumferential to resist the hoop stress resulting from lateral pressure of the confined earth. For sand fill inside the ring, this amounts to 0.33 times the combined liquid and earth vertical pressure. 2.3.2.8. Details for corrosion protection of the tank bottom from runoff and moisture are covered in Section 2.5. 2.3.2.9. Construction tolerances are to be as stated in API Standard 650, "Welded Steel Tanks for Oil Storage". 2.3.2.10. Although used successfully in many areas, these foundations may be subject to large differential settlements under certain soil conditions, and therefore may not be suitable for tanks which are sensitive to this condition, such as those with floating roofs. 2.3.2.11. See Figure 2.1. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 10 of 29 DOW RESTRICTED - For internal use only Fig. 2.1 2.3.3. Earthen Foundations 2.3.3.1. An earthen foundation may be chosen when an engineering evaluation of the site indicates the presence of competent subgrade soil capable of providing adequate structural support. 2.3.3.2. The construction of an earthen foundation could involve a rock ring with compacted earth fill, or a totally earthen mound with or without an asphalt mat. It could also be constructed completely of gravel or THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 11 of 29 DOW RESTRICTED - For internal use only crushed rock. The availability and cost of material will influence the configuration. 2.3.3.3. While this type of foundation may be relatively quick and easy to construct, its suitability will be affected by several factors, including: presence of suitable fill material; condition of the subgrade; limits on total or differential settlement; requirements for cathodic protection or leak detection systems; proposed surface finish for surrounding area; requirements for Secondary Containment and Leak Detection Systems. 2.3.3.4. Construction tolerances are to be as stated in API Standard 650, "Welded Steel Tanks for Oil Storage". 2.3.3.5. Due to the simplicity of construction, there are no practical limits on the size of tank which may be supported on this type of foundation, other than those imposed by site or material constraints. 2.3.3.6. Fill for earthen foundations should be high enough to provide good drainage away from the tank base.This must take projected settlements into account. 2.3.3.7. Although used successfully in many areas, these foundations may be subject to large differential settlements under certain conditions, and therefore may not be suitable for tanks which are sensitive to this condition, such as those with floating roofs. 2.3.4. Concrete Mat Foundation 2.3.4.1. Concrete mat foundations are typically selected because of their ability to spread loading uniformly over a large bearing surface and to minimize differential settlements that may occur. 2.3.4.2. Where the ratio of tank diameter to differential settlement is less than 200, submit the foundation design to the Foundations TRL for review. 2.3.4.3. This style of foundation is recommended for pressurized tanks in particular, and any tank where uplift resistance is required.See Figure 2.2. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 12 of 29 DOW RESTRICTED - For internal use only Fig. 2.2 2.3.4.4. Circular or octagonal concrete mat foundations are typically selected for the support of smaller tanks with diameters 40 feet or less.See Appendix D for typical tank foundation design. 2.3.4.5. The minimum thickness of concrete mat foundations is 250 mm (10in). Minimum reinforcement shall be 0.25% of the gross cross-sectional area, for each layer in each direction and a maximum bar spacing of 150 mm (6). 2.3.4.6. For tanks without leak detection systems, the mat may be constructed with a flat surface or with a crown THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 13 of 29 DOW RESTRICTED - For internal use only from the center of the tank to the outside edge of 1 2% after expected differential settlement due to consolidation. 2.3.4.7. For tanks with leak detection systems, the mat should be constructed with a minimum slope of 2% from the high point to the low point after expected differential settlement due to consolidation. This will provide adequate slope to ensure that the leak detection system remains functional with differential settlements of the tank foundation within normal limits. 2.3.4.8. In all cases, the PCE designer should be consulted on the shape and slope of mat foundations. 2.3.4.9. In paved areas this foundation fits well and makes runoff and spill containment simpler. 2.3.4.10. Concrete mat foundations provide a suitable means to build in different requirements for the installation of heating systems. 2.3.4.11. The design is commonly based on the theory that the mat is rigid and the distribution of loads on the subgrade is linear in nature.One typical method for design may be found in "Foundation Engineering Handbook"4, by Winterkorn and Fang. 2.3.4.12. Concrete mats that are not set on deep foundations may be subjected to significant bending and hoop forces as a result of differential settlement between the edge and middle of the tank. 2.3.4.13. Reinforcing the top and bottom regions is normally recommended for mat foundations. 2.3.4.14. Combination slab and ring wall configurations may be used on elevated tanks. Design ringwall according to this guideline. See Figure 2.3. 4 Hans F. Winterkorn and Hsai-Yang Fang, Foundation Engineering Handbook, (Van Nostrand Reinhold Company). THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 14 of 29 DOW RESTRICTED - For internal use only Fig. 2.3 2.3.4.15. Frost susceptibility of soils should be considered and it may be necessary to protect the foundation from heaving during winter. (See Section 2.4 on Frost Action). 2.3.5. Pile Foundations 2.3.5.1. When a tank is to be founded on very weak soils and other types of foundations will not work, when large uplift is anticipated or when tank settlement is THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 15 of 29 DOW RESTRICTED - For internal use only unacceptable, the tank could be built on pilings which extend down to suitable bearing soils or rock. 2.3.5.2. Pile foundations are the most expensive type and should be used only if all other alternatives have been explored and discarded. 2.3.5.3. A concrete pile cap is required to transfer the load from the tank to the piles. See Figure 2.4. Fig. 2.4 2.4. Frost Action 2.4.1. General THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 16 of 29 DOW RESTRICTED - For internal use only 2.4.1.1. Frost action will generally result in upward movement in susceptible soils, and subsequent reduction of soil shear strength when the frozen ground thaws. This is a cyclical seasonal occurrence. 2.4.2. Effects of Frost Action on Tanks 2.4.2.1. Differential movement of the tank itself or between the tank and any connected piping, structures, or services will potentially cause the most problems. 2.4.2.2. If differential settlements would be a problem, the following alternatives may be considered: Design connections between the tank and any auxiliary equipment or structures with potential differential settlements in mind. Provide sufficient flexibility in the design of connected piping to withstand expected strains. Extend the tank foundation to include auxiliary equipment, thus reducing differential settlements. 2.4.2.3. On tanks with diameter less than 60 feet other possibilities include: Removing frost susceptible soil from beneath the tank, and replacing it with sound fill. Beware of drainage traps in low-permeability native ground. Construct an engineered insulated foundation. Any heating systems in place to prevent tank contents from freezing may be taken advantage of. 2.5. Corrosion Protection 2.5.1. Waterproofing 2.5.1.1. The most effective way to stop or reduce the external corrosion of the tank bottom is to eliminate water intrusion. In addition, a thickened annular ring increases corrosion allowance in the area most susceptible to corrosion attack. 2.5.1.2. Water penetration from the ground up in ring foundations can be minimized or eliminated by using a geomembrane compatible with the product stored. 2.5.2. Drainage 2.5.2.1. Provide adequate drainage around tank foundations to ensure that runoff will not stand nearby. 2.5.2.2. Paved areas should be sloped at a minimum of 1 percent for at least 6 m (20 ft) away from the tank base. (Note German regulations require a minimum slope of 2 percent.) Unpaved areas should be sloped at a THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 17 of 29 DOW RESTRICTED - For internal use only minimum of 2 percent. Accent slopes adjacent to tank penetrations through slabs to minimize exposing the joint to potential spilled materials. 2.5.2.3. Safety and Loss Prevention Principles may require steeper and longer slopes in some applications. See also Spill Containment Guidelines G2D-K100-00. 2.5.2.4. When laying out drainage patterns, consider the effects of other existing or proposed tanks in the vicinity.Ensure that drainage for existing foundations is not disrupted. 2.5.2.5. Tank settlement may cause drainage patterns to be disturbed.If settlements are small, this may be corrected by building-in additional slope. If settlements are large, then it may be necessary to re-grade the area after a period of time, or delay final grading until initial consolidation is complete. 2.5.2.6. When hydrotesting the containment around any tank installation, set the hydrotest level below the elevation of the tank bottom, or provide adequate damming or other means of preventing water from entering into the foundation underneath the tank. 2.5.3. Cathodic Protection 2.5.3.1. Cathodic protection is a method to reduce corrosion of tank bottoms in a conductive electrolyte by passing sufficient electrical current from an external source to overcome any corrosion activity on the tank's metal surface. 2.5.3.2. Cathodic protection is required for tanks installed in locations with the following climate conditions: In areas where the average summer daytime temperature is 25oC (77oF) or higher; Where the average summer daytime air humidity is 75% or higher; and In marine environments. 2.5.3.3. Cathodic protection is required at the following locations: Aratu Louisiana Operations Texas Operations 2.5.3.4. Where cathodic protection is required, foundations shall be constructed according to Engineering Detail G2G-3340-87. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 18 of 29 DOW RESTRICTED - For internal use only 2.5.3.5. The use of a secondary containment system or a flexible membrane liner will affect the design of any cathodic protection system. 2.6. Seismic Conditions 2.6.1. Tank foundation design should include seismic design criteria where applicable. Check local codes and Site Variations for requirements. 2.6.2. Depending on soil conditions, some soils may offer very little shear resistance during an earthquake.Lateral forces should be taken by the concrete foundation or pile foundation only. 2.7. Wind Condition and Internal Tank Pressure 2.7.1. The foundations for tanks shall be designed to resist internal pressures. The tank design pressure shall be used for calculation of uplift forces (if test pressure is to be greater than the normal 1.25 times design pressure, increase the design pressure accordingly for design of the foundation). The tank bottom weight as well as any corrosion allowance should not be considered in resisting uplift forces. 2.7.2. Where the internal pressure is resisted by a counterbalancing weight (such as a concrete ringwall), the resisting weight shall be 1.5 times the uplift force. 2.7.3. Where the uplift forces are resisted by piling, treat the force as a live load.Any weight contribution of the foundation should also be used to resist the uplift force. 2.7.4. Where the uplift forces are resisted by a mat type foundation, treat the force as a live load and assume the mat is subjected to a uniform downward pressure counterbalanced by a uniform upward force at the tank perimeter. The internal pressure does not get transferred into the soil.See Appendix D for an example calculation. 2.8. Cost 2.8.1. Each plant site has unique conditions such as frost heave, excessive settlement, weak soil, etc., that can influence the cost. Therefore, it is recommended that a study be made for each design to determine the minimum requirements and still have a safe design. 2.8.2. The following cost factors are based on a 100 feet diameter tank built in the Texas Gulf Coast Area. The base factor of 1.00 is for a conventional concrete ring foundation similar to Figure 2.1 (without secondary containment), and estimated at $27,000 in May, 1984. Note that these factors may be sensitive to local conditions. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 19 of 29 DOW RESTRICTED - For internal use only FOUNDATION TYPECOST FACTOR CONC RING BASE ESTIMATE1.0 CONC RING WITH CLAY LINER1.2 CONC RING WITH GEOMEMBRANE1.3 CONC SLAB WITH GRADE BEAM1.4 CONC RING & TANK W/SECOND BOTTOM4.4 CONC RING & TANK ON STEEL MEMBRANE 4.6 PILE CAP7.2 3. ENVIRONMENTAL CONSIDERATIONS 3.1. Leak Detection and Collection Systems 3.1.1. The function of a leak detection system is to provide notice that the primary containment (tank) has failed and that a leak has developed.This is a different function from that of dikes, impoundment basins, or other Secondary Containment Systems whose function is to collect and hold the contents of the tank in the event of spills or catastrophic failure of the tank. 3.1.2. Leak detection systems are required for all tanks which contain material that may contaminate soil or ground water, this applies to water and condensate tanks if service change is expected on these tanks. 3.1.3. Currently, the most widely used leak detection systems for tank foundations are those that rely on gravity flow of the leakage and visual inspection of the system. There are also leak detection systems which utilize various types of instrumentation to rapidly detect and sometimes pinpoint the location of leaks.These range from multi-point volatile gas sensors to single probes or installed grid systems that measure changes in electrical conductivity of their surroundings brought about by a leak. Instrument application departments should be contacted for assistance. 3.1.4. The materials chosen for construction of the system must have demonstrated capability to resist degradation due to the full range of operational conditions which can be THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 20 of 29 DOW RESTRICTED - For internal use only reasonably expected. Refer to the Dow Guideline G2D-K100-00, Spill Containment Guidelines. 3.1.5. Any style of foundation is easily adaptable to providing a good external leak detection system. 3.1.5.1. Concrete rings provide a convenient means of confining a permeable sand or gravel beneath the tank, which can in turn act as a drainage medium. Some form of barrier is required to prevent any leaks from penetrating into the ground. See Engineering Detail G2G-3340-87. 3.1.5.2. Earthen foundations require an additional membrane and permeable medium. Many types are available, with the most common being a synthetic membrane. 3.1.5.3. Concrete mat foundations, that are to be considered as secondary containment barriers, in many cases must either be coated or have a membrane covering. 3.1.5.4. When heat or chemical compatibility does not permit the use of membrane or protective coatings, specialty concrete may be used as a barrier. 3.1.5.5. Any tank may be fitted with a false bottom inside the tank itself. This is most commonly a steel plate, but other materials have been successfully used, especially in retrofit situations. See Section 4, "Retrofit and Repair". 3.1.6. Tank edge settlements will usually be less than center settlements, often by as much as one-third to one-half.Slopes on leak detection systems should be designed to take this into account. 3.1.7. The use of a leak detection system or a flexible membrane liner will affect the design of any cathodic protection system. 3.2. Spill Containment 3.2.1. Spill containment shall conform to G2D-K100-00 Spill Containment Guidelines. 4. RETROFIT AND REPAIR 4.1. False Bottoms 4.1.1. False bottoms are placed in existing tanks to either correct a leaking condition or upgrade the tank with a leak detection system.Work with process containment team for these details. 4.2. Foundation Repair 4.2.1. Tank bottoms suffering unacceptable differential settlements either at the edges or across the bottom can be leveled by either mud jacking or pressure grouting. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 21 of 29 DOW RESTRICTED - For internal use only Small tanks may be lifted at the edges by jacks and shims, and the foundation repaired with dry-pack grout.4.3. Local Shear Soil Failure Repair 4.3.1. Tanks supported by weak soils can experience local shear failure when the tank is filled too fast.This happened to a 200 foot diameter tank located in Texas Operations Oyster Creek Plant. To repair the foundation, the dike area for this tank was flooded and the tank was floated off its rock ring. The portion of the rock ring and the soil under it was removed to the slip plane and recompacted. The dike was again flooded and the tank floated back on its foundation.If there had not been the dike, "air cushions" could have been used to move the tank. 5. Appendices 5.1. A Site Investigations 5.2. B Frost Action 5.3. C Controlled Tank Settlement 5.4. D Foundation Design for Tank With Internal Pressure THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 22 of 29 DOW RESTRICTED - For internal use only APPENDIX A SITE INVESTIGATIONS A.1. OBJECTIVE OF SITE INVESTIGATIONS A.1.1. Characteristics to be determined may include: A.1.1.1. The nature and sequence of strata. A.1.1.2. Groundwater conditions. A.1.1.3. Physical properties of the soils and rock. A.1.1.4. Mechanical properties of the soils and rock, such as strength and compressibility. A.1.1.5. Existing environmental conditions. A.2. BACKGROUND INFORMATION A.2.1. A preliminary research program could include: A.2.1.1. Study of existing soils reports and structures on a developed site. A.2.1.2. Analysis of geological and geotechnical maps, including serial or satellite photos in undeveloped areas. A.2.1.3. Becoming familiar with climatic conditions and constraints, local codes and bylaws, and local practices in case where the designer is new to a site or an area. A.2.1.4. Determining the presence of existing structures or utilities which could interfere with the construction or performance of the proposed foundation. A.2.1.5. The environmental representative for the site should be contacted to obtain historical site use information. Potential soil contamination from past land use may restrict design options. A.2.2. The designer should also become familiar with the type of structure to be built, including its starting date, intendedconstruction method, and estimated duration of construction. A.2.3. Additional information, beyond a subsurface soils report, would also be useful in preparing and evaluating plans. These include: A.2.3.1. Availability of utilities, ie. water, power, sewer, etc. A.2.3.2. Access to the site. A.2.3.3. Availability of space for material storage or layout. A.2.3.4. Environmental concerns. A.2.3.5. Labor supply. A.3. EXTENT OF INVESTIGATION A.3.1. The total investigative effort should provide sufficient information for a thorough understanding of the total site condition. A.3.2. The extent of any new study will be determined by several factors, including: THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 23 of 29 DOW RESTRICTED - For internal use only A.3.2.1. The amount of information retrieved from existing sources. A.3.2.2. The type of foundation and structure planned. A.3.2.3. The cost of investigation in relation to the project budget. A.4. SOIL BORINGS A.4.1. Note that soil bore holes may become a conduit for transmission of contaminants through soil strata. Consult the environmental control and/or engineering departmentsfor specific requirements. A.5. SOILS INVESTIGATION A.5.1. The physical and mechanical properties of soils are determined by either in situ or laboratory testing, or a combination of both. A.5.2. It is considered to be good practice to combine field and laboratory tests for strength and compressibility, whenever possible. A.5.3. As a minimum, the testing should provide the following: A.5.3.1. Soil profile, including classification according to a recognized standard classification system (i.e., Unified Soil Classification System). A.5.3.2. Location of water table. A.5.3.3. Moisture content, including Atterburg Limits. A.5.3.4. Soil density. A.5.3.5. Undrained shear strength of cohesive soils. A.5.3.6. Standard penetration test index. A.5.3.7. Partial sieve analysis or grain size distribution. A.5.4. Additional properties may be obtained as required by the analysis technique to be used, environmental considerations, proposed construction techniques, etc. A.5.5. A report should be prepared for each site investigation, and should include as a minimum: A.5.5.1. Terms of reference of the investigation. A.5.5.2. Procedures used in the investigation. A.5.5.3. Topography, vegetation, and other surface features, for an undeveloped site. A.5.5.4. Soil profile and properties. A.5.5.5. Groundwater observation. A.5.5.6. Foundation studies, including recommendations for alternative methods of support, listing capacities and expected settlement performance and construction procedures if appropriate. A.5.6. Additional guidelines for soils investigative reports may be found in the Canadian Foundation Engineering Manual, Chapter 4, or Michigan Division Engineering Practice G2D-2003-15 Geotechnical Eng/Site Investigation Project Flow Chart. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 24 of 29 DOW RESTRICTED - For internal use only APPENDIX B FROST ACTION B.1. DEFINITION B.1.1. Frost action is the term used to define the effects on soil and structures due to seasonal freezing and thawing of the ground. B.2. CONDITIONS CAUSING FROST ACTION B.2.1. Freezing Temperatures B.2.1.1. Ground freezing will occur when average daily mean air temperatures drop below freezing for a duration of several weeks. B.2.1.2. Snow cover and exposure to wind are additional factors which affect the amount of ground freezing that occurs. B.2.1.3. A correlation may be drawn between the cumulative total of the difference between daily mean air temperature and the freezing point, known as the freezing index, and the depth of frost penetration into the ground. B.2.1.4. Charts are available which indicate the freezing index for various locations. B.2.2. Frost Susceptible Soils B.2.2.1. Frost susceptible soils are those soils in which there are fine pores to support the mechanism of ice segregation and the formation of ice lenses. B.2.2.2. Criteria established by Casagrande estimate the susceptibility of a soil: "...expect considerable ice segregation in uniform soils containing more than 3 percent of grains smaller than 0.2 mm, and in very uniform soils containing more than 10 percent smaller than 0.02 mm". B.2.2.3. Even with such criteria, the borderline between soils that are and are not susceptible to frost action is not well defined, and those soils which are near these limits should be treated with caution. B.3. MECHANICS OF FROST ACTION B.3.1. Mechanics of Frost Action B.3.1.1. The basic causes of most problems associated with frost action are ice segregation and lensing in fine grained soils. B.3.1.2. Water may be drawn through capillary action to the frost front from the unfrozen soil to form distinct layers (lenses) of ice.Lense formation can cause large increases in the soil volume, exceeding the 9 percent growth due to water/ice phase change. B.4. PROBLEMS ASSOCIATED WITH FROST ACTION B.4.1. Frost Heave B.4.1.1. Frost action can cause heaving in the soil, which can be several times the original volume of the subgrade. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 25 of 29 DOW RESTRICTED - For internal use only B.4.1.2. If volumetric expansion is restrained, large pressures could develop between the foundation and the bearing surface.Contact pressures of 37,000 to 40,000 psf have been documented. B.4.2. Thawing B.4.2.1. During a seasonal change to warmer temperatures, thawing of the ground takes place causing the release of water in the soil.Since thawing progresses from the surface downward, the frozen zones underlying the thawed zone act as an impervious layer trapping in excess water. The upper layer becomes softer causing a reduction in the original shear strength of the soil. B.5. MINIMIZING OR CONTROLLING THE EFFECTS OF FROST ACTION B.5.1. General B.5.1.1. The design of foundations against frost action rarely implies incorporating additional structural strength.Instead, techniques are used to avoid the problem by eliminating one or more of the factors that together result in ice segregation and frost heaving. B.5.2. Placement of Foundation Below Grade B.5.2.1. Local building codes usually establish the depth at which frost penetrates the subgrade (frost line).Foundations are usually designed and constructed to bear on soil at or below the frost line. B.5.3. Placement of Non-Susceptible Soil B.5.3.1. Another method used to counter frost action is the removal of frost susceptible soil to a depth below the frost line.The void is replaced with a soil or aggregate exhibiting good resistance to frost action. While simple, this may be expensive and introduces a new problem in providing adequate drainage for the fill material. B.5.4. Do Nothing B.5.4.1. In cases where cyclical up and down movements of the structure can be tolerated, an elevated foundation with adequate drainage may be considered. The elevated foundation should contain a free draining soil such as gravel and the surrounding area should be sloped away from the structure. B.5.4.2. Differential movements may develop between structures, equipment and piping.This needs to be considered when selecting the foundation, and when designing these facilities. B.5.5. Insulation B.5.5.1. Styrofoam TM* insulation may be placed beneath and adjacent to the foundation to prevent the ground from freezing.The most severe limitation to its use is the presence of solvents in the ground or leaks in the containment above. Frequent cases have been noted where polystyrene insulation either disintegrated or formed a gel-like consistency when placed in a contaminated location.This causes a loss of bearing surface and bearing capacity.THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 26 of 29 DOW RESTRICTED - For internal use only B.5.5.2. The techniques of insulating the foundation should only be used in situations where the structure, or any attachments, will not be able to withstand cyclical up and down movements. For tanks exceeding 30 feet in diameter, alternative measures should be investigated. B.6. ADFREEZING B.6.1. General B.6.1.1. Adfreezing is a phenomenon that occurs as a consequence of a frozen soil adhering to a foundation wall.Adhesion to the wall takes place when temperatures fall below freezing causing the soil to "stick" to the adjacent surface. Upheaving pressure is transmitted.Typical forces average around 15 psi for steel and 10 psi for concrete and wood. Peak pressures can be found at 20 to 35 psi. B.6.2. Controlling Adfreezing B.6.2.1. To minimize adfreezing, backfill around an excavation with a nonsusceptible soil. Drainage should also be investigated and considered for the soil zone surrounding the foundation. B.6.2.2. The ground immediately around the foundation may be insulated. B.6.2.3. Pile foundations should be carried deep enough into the ground so that sufficient uplift resistance may be developed. When determining the length of pile required, the following must be considered: B.6.2.3.1. Dead load of any supported structure, plus the weight of the pile itself, may be applied as a resisting force.B.6.2.3.2. Uplift forces will be generated up to the design depth of frost penetration. B.6.2.3.3. Soil resistance will be generated only below the design depth of frost penetration, or soil dessication. B.6.2.3.4. Safety factor against uplift should be greater than 1. B.7. References B.7.1. ASCE Proceedings Vol. 99, No. SM 9, dated September 1973. (For design of insulation system) B.7.2. Paper on E.I. Robinski and K.E. Bespflug entitled "Design of Insulated Foundations", from the Journal of Soil Mechanics and Foundation Design, September 1973. (Further information on the design techniques and methods) B.7.3. Dow Chemical Company "Soil Insulation". THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 27 of 29 DOW RESTRICTED - For internal use only APPENDIX C CONTROLLED TANK SETTLEMENT C.1. This is a method of consolidating the soil, thus gaining strength, under a storage tank by incrementally loading the tank with water or product. This has been done numerous times by Dow Engineering groups, but occasional problems have occurred. The following is one method for controlled settlement. C.2. It is important to make soil calculations to determine the height of water to use for the initial increment. A safety factor of 1.7 with the initial water height is conservative, yet consolidation will occur. DON'T GUESS! This initial height of water may vary from 10 feet to 40 feet depending on the existing soil strength. Elevations should be taken around the tank foundation before adding water. Additional elevations should be taken every few days to determine settlement. A time versus settlement curve should be drawn. When settlement approaches 1/8 inch per day, another 4 foot increment of water may be added. Depending upon the soil, it may take two days to over 30 days to reach this settlement rate. Continue adding increments until the tank is full. Total settlement may be from a few inches to a few feet depending on the starting soil strength. It is very important that you don't put too much water in at one time because this would overload the soil and cause a soil failure. C.3. The most important thing, regardless of the method, is to properly communicate with the client, or whoever is going to add the water increments. This communication should be in writing and should specifically state how and when to add the increments. C.4. Example Calculation Of Controlled Tank Settlement Tank V-64 O.C.D. 100' X 48' SOIL COHESION, C = 500psf ULT BEARING CAPACITY = 7.2 X C = 3600 psf FOR F.S. = 1.7 FOR INITIAL INCREMENT SOIL PRESS = 3600/1.7 = 2117 psf 1st INCREMENT (WATER) = 2117/62.5 = 34'F.S. = 1.7 ADD 4' INCREMENTS AFTER ELEVATION READING (EVERY 3 DAYS) SHOW SETTLEMENT CURVE IS FLATTENING OUT = APPROX .01' PER DAY SETTLEMENT. AT 4 WEEKS PER INCREMENT 48 - 34 = 14' 4 INCREMENTS (4 WEEKS) = 16 WEEKS C.5. Example Communication To Client Of Controlled Tank Settlement Procedure SETTLEMENT OF V-64 Tank v-64, 100 feet diameter by 48 feet high, can be filled initially to a depth of 34 feet. Elevations will be taken on the major axes of the concrete ring before filling is begun and after the initial filling is completed. A curve will be plotted of settlement vs. time on this THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 28 of 29 DOW RESTRICTED - For internal use only tank. After the settlement rate has begun to diminish, elevations will be taken once per week. When the rate of settlement from the initial filling reaches approximately .01 foot per day, I will notify you that a 4-foot increment of water may be added. The same monitoring procedure will be used until the rate of settlement again approaches approximately .01 foot per day. this sequence will be followed until the tank is filled. As a time estimate, allow approximately 4 weeks for the initial loading to reach equilibrium and approximately 16 weeks for the 4 foot increments for a total of 20 weeks. The actual time required may vary, depending on the observed rate of settlement as reflected by the settlement curve. Calculations are enclosed. THE DOW CHEMICAL COMPANYDESIGN AID CIVIL/ARCHITECTURALG2D-K120-00 GLOBAL30-JUN-2005 Page 29 of 29 DOW RESTRICTED - For internal use only APPENDIX D FOUNDATION DESIGN FOR TANK WITH INTERNIAL PRESSURE TANK DIAMETER D = 40' TANK HEIGHT H = 40' TANK WEIGHT (EMPTY) = 93 k TANK WEIGHT (FULL) = 3228 k INTERNAL PRESSURE q = 10 PSI OR 1.44 ksf ALLOWABLE SOIL BEARING = 2.5 ksf PRESSURE POISSON RATIOv= 0.2 FOR CONCRETE REINFORCING STEEL Fy = 60 ksi ASSUME 42' DIAM. X 3' THICK MAT RADIUS a = 21' 3.142 X 42' X 42' AREA OF FOUNDATION =----------------- = 1385 sq. ft. 4 3228 ACTUAL SOIL PRESSURE = ------ = 2.1 ksf < 2.5 ksf so ok 1385 ALL INTERNAL PRESSURE OF THE TANK IS TAKEN BY CONCRETE MAT ONLY. MAXIMUM MOMENT @ CENTER BY USING STRENGH DESIGN. u X q X a X a (3 + v) u = 1.7 Mc = --------------------- 16 1.7 X 1.44 X 21' X 21' (3 + 0.2) =-------------------------------- =216 k - ft 16 REINFORCING STEEL d = 33" 216 X 12" Ast = --------------------=1.61 sq. in in./ft. 0.9 X 60 X 0.9 X 33" USE # 8 @ 6" E.W. @ BOTTOM USE MIN. REINF. @ TOP REINFORCING CAN BE REDUCED AWAY FROM THE CENTER AS MOMENT REDUCES. i 06/30/05, MOC2005_02566, By: Darryl Baron, Supercedes Issue Date: 22-DEC-2004, General Revisions throughout document.