Before you BeginThis document presents recommended buoyancy control methods for Infiltrator Systems Inc.’s (Infiltrator’s) IM-Series tanks. Tank buoyancy control methods must be implemented according to state and/or local regulations, which may supersede the guidelines in this document. If unsure of the requirements for a particular site, contact the local health department or permitting authority.
This document provides procedures to determine if tank buoyancy control is required based on site conditions. Please obtain the following information to determine if control is necessary and what methods are applicable:• Infiltratortankmodel• Maximumheightofwateroutsidethetankandabovethetankbottom
elevation• DepthofsoilcoveroverthetanktopOnce tank buoyancy control measures are determined to be required and amethodhasbeenselectedandimplemented,refertoInfiltratorIM-SeriesTankInstallationInstructionsandRiserConnectionGuidancedocuments,as applicable, for completing the installation.
How to Use this Document 1. BecomefamiliarwiththedescriptionsintheCompatibleDevicesand
Products section. 2. Verify that the water level outside the tank is below the outlet pipe
saddleheightusingStep1,Tables1and2,andFigure1. 3. DetermineifbuoyancycontrolisrequiredusingStep1,Table2.
Ifbuoyancycontrolisrequired,proceedtoStep2. 2. UsetherespectivetableforthetankmodelfromStep2,Table2to
determine the appropriate buoyancy control methods for the site conditions.
5. Once a preferred buoyancy control method is selected, follow the proceduresforimplementationprovidedinStep3.
Parts and SuppliesThe parts and supplies necessary are to be purchased separately from the tank. All parts and supplies are either commercially available or available throughInfiltrator’snetworkoftankdistributors.Somepartsmayrequirefabrication on site using common construction practices.
Compatible Devices and ProductsInfiltratortanksarecompatiblewiththefollowingproductsforbuoyancycontrol:• Tie-down straps:high-tensile-strengthwebbing,10,000lb(4,500kg)
minimumcapacity,nylonorpolyester,withcorrosion-resistanthardware. • Concrete deadmen anchors:concrete-filledplastichalfpipe,precast
parking bumper, precast traffic barrier, or poured block. • Helical anchors:Chance™No-WrenchScrewAnchorswithminimum
6-inch(150mm)diameter,Class7orequal.
Tie-Down StrapsStrapsarecommerciallyavailableinvaryinglengths and with assorted hardware and tighteningoptions.Nylonorpolyesterstrappingwithminimum10,000lb(4,500kg)capacityisrequiredforbuoyancycontrolusewithInfiltratortanks.Placestrapsupandoverthetankatspecifiedlocationsonly(seeFigure5).Tightenstrapssnuglywitharatchetorturnbucklesystemtoremoveallslackandslightlypre-loadthe system. All connections, fittings, and hardware must be corrosion resistantorcoatedwithepoxyorothercorrosion-resistantmaterialstoinhibitdeteriorationinthesubsurfaceenvironment.Considerencapsulatingsuchcomponentsinheat-shrinktubingorpaintingonadditionalcorrosion-resistant coatings prior to burial.
Concrete Deadmen AnchorsRecommendedconcretedeadmenanchorsincludefilledplastichalfpipe,precast parking bumpers and traffic barriers, and poured blocks. The weight of the deadmen anchors combined with the weight of soil above themprovidesbuoyancycontrolwhenproperlysecured.Deadmenanchorsareplacedatthebottomofthetankexcavationonoppositesidesofthetank.Thedeadmenanchorsarefastenedtoeachotherwithtie-downstraps placed up and over the tank at the locations specified for each tank model(seeFigure5).
Concrete-filled plastic half pipeUseSchedule40PVCplasticpipehavingaminimuminsidediameterof15inches(375mm)orHDPEcorrugatedpipehavingaminimuminsidediameterof18inches(450mm)cutinhalflengthwise.Fillwithconcretehavingaminimumunitweightof145lbs/ft3(2.32metrictons/m3)reinforcedwiththreeequallyspaced40-grade, 1/2-inch(13mm)diametersteelbars.Weightis61lbs/ft(91kg/m)minimum.
Concrete parking bumperUsecommerciallyavailablesteel-reinforcedparking bumpers with typical dimensions of 12incheswideby6incheshigh(300mmx150mm).Weightis58lbs/foot(86kg/m)minimum.
Concrete traffic barrierUsecommerciallyavailablesteel-reinforcedconcrete traffic barrier or equivalent. Typical dimensionsincludea24-inch-widebasetaperingtoa6-inch-widetop,withaheightofapproximately 32inches(600mmx150mmx800mm). Weightis390lbs/foot(580kg/m)minimum.
Poured BlocksConcreteprecasterscanpourblocksofvarious dimensions and weights. Blocks are often an affordable option if they satisfy the weight requirements for use as buoyancy control(seeTable2andtheSupplementalForcesectionofStep2formoreinformation).
Helical AnchorsChance™No-WrenchScrewAnchorswitha6-inch(150mm)diameterflight,Class7,or equal. These anchors rely on the shear strength of the soil combined with the weight of the soil above the anchor flight to provide holding strength. Proper installation is to 4feet(1.2m)belowthebottomofthetankexcavationandtowithin5°ofalignmentwiththewebbingload.Determinetheproper locations for anchor installation to ensurethattie-downstrapswillbealignedproperlyforeachtankmodel(seeStep3:Implementation),andfollowanchormanufacturer installation instructions.
18 in[450mm]
12 in[300 mm]
6 in[150 mm]
24 in[600 mm]
32 in[800 mm]
Quick4 Plus Equalizer 36 LP
Typical working torque:¾”Rod400ft.lbs.(542N•m)1”Rod1,000ft.lbs.(1,356N•m) 1¼”Rod2,300ft.lbs.(3,118N•m)
Infiltrator IM-Series Tank Buoyancy Control Guidance
MARCH 2015
15 in [315 mm] to18 in [450 mm]
Steel Rebar
18 in[450mm]
12 in[300 mm]
6 in[150 mm]
24 in[600 mm]
32 in[800 mm]
Quick4 Plus Equalizer 36 LP
Contact Infiltrator Systems’ Technical Services Department for assistance at 1-800-221-4436.
Table 1: Infiltrator tank models1 and conditions requiring buoyancy control
Parameter I: Water height2 above tank bottom
Parameter II: Soil cover depth above tank top3
A B
6 in (150 mm) to 12 in (300 mm)
Above 12 in(300mm)
1 Above outlet pipe saddle4
(greater than 43”) Donotinstall Donotinstall
2 36” (900 mm) to 43” (1075 mm) to outlet pipe saddle All models NotRequired
3 30” (750 mm) to 36” (900 mm) IM-1530 NotRequired
4 Less than 30” (750 mm) NotRequired NotRequired
Design Example Table 1: Infiltrator tank models and conditions requiring buoyancy control
Parameter I: Water height above tank bottom
Parameter II: Soil cover depth above tank top
A B
6 in (150 mm) to 12 in (300 mm)
Above 12 in(300 mm)
1 Above outlet pipe saddle Donotinstall Donotinstall
236” (900 mm) to 43” (1075 mm) to outlet pipe saddle
All models NotRequired
3 30 in (750 mm) to 36 in (900 mm) IM-1530 NotRequired
4 Less than 30 in (750 mm) NotRequired NotRequired
Step 1 – Determine Need for Buoyancy ControlRequiredinformation:themaximumheightofwateroutsidethetankandabovethetankbottomANDthe depth of soil cover above the tank top. Tank buoyancy control may be required if the water level outsidethetankhasthepotentialtorise30inches(750mm)ormoreabovethebottomofthetank,ANDlessthan12inches(300mm)ofsoilcoveristobeplacedasbackfilloverthetanktop.Otherwise,no buoyancy control is required.
Allowable Subsurface Water ElevationGroundwaterelevation,groundwatertable,andwatertablearetermsforthesubsurfaceconditionwhere water is held in the subsurface soil pores or rock. The seasonal high groundwater elevation represents the highest point the water table has the potential to reach at any time of the year, and is not necessarily the level at which groundwater may be observed seeping from the soil at the time oftankinstallation.Ingeneral,aqualifiedsoilevaluatororengineercanestimatetheseasonalhighgroundwaterelevationfromcarefulexaminationofthesoilprofile.Under certain conditions, a perched water table may be present in the subsurface. A perched water tableoccurswherethereisanimpermeableorlow-permeabilitysoilthatcauseswatertobepresentinthesoilporesabovethemainwatertable.Aperchedwatertableelevationmayexceedtheseasonalhigh elevation of the main water table. The vertical position of the tank must account for both the seasonalhighgroundwatertableandanyexistingorfutureperchedwatertablecondition.Verify that the subsurface water level will not exceed the height of the outlet pipe saddle of the tank, as show in Tables 1 and Figure 1.
Table 1 Instructions 1. Intheleft-handcolumnofTable1,locatetherowcorrespondingtotheheightofthewaterelevation
outsidethetankandabovethetankbottom(ParameterI)forthesiteconditions.SeeFigure2. 2. Followthatrowtotherightuntilreachingthecolumncorrespondingtothedepthofsoilcoverproposed
abovethetanktop(ParameterII).SeeFigure2. 3. Ifthetankmodelislistedinthatcell,thenbuoyancycontrolisrequired(proceedtoStep2).Ifthetank
model is not listed in that cell, then no buoyancy control is required. 4. Thetankshallnotbeinstalledwherethewaterleveloutsidethetankexceedstheheightoftheoutlet
pipe saddle.
NOTES:1.Infiltratortankmodelsinclude:IM-540,IM-1060,andIM-1530.2.Waterheightcorrespondstoseasonalhighgroundwaterelevationorperchedwaterelevationmeasuredfrombottom-of-tankelevation.
3.Minimum6inchessoilcoverbackfillisrequired.4.Thetankshallnotbeinstalledwherethewaterleveloutside
thetankexceedstheheightoftheoutletpipesaddle.
Figure 2: Buoyancy Control Parameters
Design ExampleAcontractorplanstoinstallanIM-1060tankwherethewaterleveloutsidethetankhasthepotentialtoriseto37inches(940mm)abovethetankbottom(ParameterI),andthedesignplancallsfor8inches(200mm)ofsoilcoverabovethetopofthetank(ParameterII).InStep1,Table1,a37-inch(940-mm)exteriorwaterheightcorrespondstorow2(36inches[900mm]tooutletpipesaddle)underParameter1.The8-inch(200-mm)soilcovercorrespondstocolumnA(6inches[150mm]to12inches[300mm])underParameterIIinTable1.AttheintersectionofParameterI,row2andParameterII,columnA,Cell2Aindicates“Allmodels”,meaningalltankmodels,includingtheIM-1060,requirebuoyancycontrolundertheseconditions.ReferringtoStep2,Table2,undertheIM-1060heading,Case1wouldapplyfor37inches(940mm)ofwaterabovethebottomoftankand8inches(200mm)ofsoilcover.Availableoptionsareasfollows(seespecificstrappingandconstructioninformationunderStep3):•IfconcreteblockisspecifiedtoanchortheIM-1060,thetotalcombinedminimumweightofblocksplacedoneachsideofthetankshallbe2,700pounds(1,225kg). Thesizeandshapecanbedeterminedbylocallyavailablematerials.Connectusingtwostraps.
•Forconcrete-filledhalfpipeandconcretetrafficbarrier,theminimumlengthoneachsideofthetankwouldbe4.2feet(1.3m),whileatleast4.5feet(1.4m)ofconcreteparkingbumperwould be required. These controls would be connected with two straps, ensuring that the controlextendsaminimumof6inches(150mm)beyondthestrappositions(seeFigure3).
•Ifhelicalanchorswereselected,aminimumoftwo6-inch(150mm)diameteranchorspersideoftank(4total)wouldbeinstalledusingtwostraps.
Figure 1: Water Elevation
Parameter IWater Height
Above Tank Bottom
Parameter II Depth Of Soil CoverAbove Top Of Tank
Maximum AllowableWater Elevation Outside of the Tank Corresponds to Outlet Pipe Saddle Invert
Tank Base
6” min – 48” max.
13”
Seasonal HighGroundwater 43” (1075 mm) max. Above Tank Bottom
Depth of Soil Cover Above Tank Top
Top Of Tank
Contact Infiltrator Systems’ Technical Services Department for assistance at 1-800-221-4436.
Step 2 – Determine Buoyancy Control MethodStep2isusediftheStep1analysisshowsthatbuoyancycontrolisrequiredforthetankmodelandtheconditionsofinstallation.Asbefore,themaximumheightofthewateroutsideofthetankandabovethetankbottomANDthedepthofsoilcoverabovethetanktopmustbeknownfortheinstallationconditionstocompleteStep2.
Table 2 InstructionsForeachtankmodel,findtheCaserowontheleftsideofthetablethatcorrespondstoboththewaterheight(ParameterI)andsoilcovermeasurements(ParameterII)forthetankinstallationconditions.Followtherowtotherightforalistingoftheappropriatebuoyancycontrolmethodsfortheinstallationconditionsundereachmethoddescriptioncolumn.RefertotheCompatibleDevicesandProductsandStep3–Implementationsectionsofthisdocumentfor additional information.
Supplemental ForceTheminimumsupplementaldownwardforcerequiredisincludedinTable3toallowcustombuoyancycontrolmethods.Thesevaluesincludeafactorofsafetyof1.5appliedtothecalculatedforcerequiredtorestrainthetank.Custom-designedbuoyancycontrolmethodsshallconsidersaturatedconditions.Solongasbuoyancycontrolisprovidedthatsuppliestheminimumweightlistedinthetable(forpoured-concreteblocksorothermethodsdesignedbythirdparties),thetankswillbestableforthewaterheightoutsidethetankandabovethetankbottomandcorrespondingsoilcoverconditions.AllInfiltratorstrappingandfasteningrecommendationswouldstillapplyforcustom-designedbuoyancycontrolmethods.ContactInfiltrator’sTechnicalServicesDepartmentwithanyquestionsregardingsupplementalforcerequirements.
Table 2: Buoyancy Control Selection
Case Parameter I:Water height above tank bottom
Parameter II:Soil cover depth above
tank top
Minimum supplemental force required1
(total, both tank sides)
Buoyancy Control Methods (minimum per side of tank)
Concrete-filled half pipe
(min. length/side)
Concrete parking bumpers
(min. length/side)
Concrete traffic barriers
(min. length/side)
Helical anchors
(min. no./side)
IM-540
1 36in(900mm)tooutletpipesaddle2 6in(150mm)to12in(300mm) 2,200lbs(1,000kg) 3.8ft(1.2m) 3.8ft(1.2m) 3.8ft(1.2m) 2
IM-1060
1 36in(900mm)tooutletpipesaddle2 6in(150mm)to12in(300mm) 2,700lbs(1,225kg) 4.2ft(1.3m) 4.5ft(1.4m) 4.2ft(1.3m) 2
IM-1530
1 30in(750mm)tooutletpipesaddle2 6in(150mm)to12in(300mm) 4,300lbs(1,955kg) 6.3ft(2.0m) 6.5ft(2.0m) 6.3ft(2.0m) 2
NOTES:1.SeeSupplementalForcediscussionbelow.2.IM-Seriesoutletpipesaddleheightis43inches(1,075mm)abovetankbottom.
Contact Infiltrator Systems’ Technical Services Department for assistance at 1-800-221-4436.
33"
38"
63"
StrappingPreparationandfasteningofwebbingto/overthetanksiscriticalfortankstability under constant and fluctuating water conditions both inside andoutsidethetank.StrapsmustbeplacedatthespecifiedstrappinglocationsforeachmodelasillustratedinFigure5.TheIM-Seriestankstrapping locations correspond to structurally reinforced areas of the tank body.Strapsmustneverbeplacedoveraccessopenings,lids,orinlet/outletpiping.Strapsmustbetightenedwitharatchetorturnbucklesystemtoremoveslackandslightlypre-loadthesystem.
STRAPPING NOTES:1. Thebuoyancycontrolshallbecenteredacrossthestraps(excludeshelicalanchors).Thecontrolshallextendaminimumof6inches(150mm)beyondthemaximumstrapwidth(seeFigures3and5).
2. Theminimumdeadmanlengthcorrespondstothetankmodel-specificstrapwidthplus12inches(300mm).
Backfill and CoverPlace backfill between deadman anchor and tank sidewall to fully fill void andtankbodycorrugations.Aminimum6”layer(150mm)ofsuitablecovermaterialisrequiredoverallInfiltratortankinstallations.Moundcovertodirectsurfacewaterdrainageawayfromthetankexcavationfootprint.Establishastrongstandoferosion-resistantvegetation.RefertoInfiltratorIM-SeriesTankInstallationInstructionsforcompletebackfillingandcoverprocedures.
General Specifications• Priortogrounddisturbance,checkforsubsurfaceobstructionsand
utilities in conformance with applicable requirements.• Excavationsshallconformtoapplicablesafetyregulations.• FollowmanufacturerinstructionsforallproductsanddevicesusedforInfiltratortankbuoyancycontrol.
• Buoyancycontrolmethodsdescribedhereindonotaccountforunanticipated conditions such as surface flooding or other natural disasters, unintended removal of cover fill over tank, etc.
• Buoyancycontrolmethodsdescribedhereinarerecommendationsonly;consult a professional engineer if desired.
4BusinessParkRoad P.O.Box768 OldSaybrook,CT06475860-577-7000•Fax860-577-70011-800-221-4436www.infiltratorsystems.com
U.S.Patents:4,759,661;5,017,041;5,156,488;5,336,017;5,401,116;5,401,459;5,511,903;5,716,163;5,588,778;5,839,844CanadianPatents:1,329,959;2,004,564Otherpatentspending.Infiltrator,Equalizer,Quick4,andSideWinderareregisteredtrademarksofInfiltratorSystems,Inc.InfiltratorisaregisteredtrademarkinFrance.InfiltratorSystems,Inc.isaregisteredtrademarkinMexico.Contour,MicroLeaching,PolyTuff,ChamberSpacer,MultiPort,PosiLock,QuickCut,QuickPlay,SnapLockandStraightLockaretrademarksofInfiltratorSystemsInc.PolyLokisatrademarkofPolyLok,Inc.TUF-TITEisaregisteredtrademarkofTUF-TITE,INC.Ultra-RibisatrademarkofIPEXInc.©2015InfiltratorSystems,Inc.Allrightsreserved.PrintedinU.S.A.
Step 3 – ImplementationEffectivebuoyancycontrolofInfiltratortanksrequirescarefulpreparation,thoroughexcavation,preciseplacement,securestrappingandproperbackfilling, as described and illustrated below.
Excavation RequirementsItisrecommendedthattheexcavationwidthprovideaminimumof36inches(900mm)clearancebeyondthetankonallsideswhenutilizingbuoyancycontrol.Thiswillallowsufficientspacewithintheexcavationtoplacedeadmenanchorsandfastenstrapping.Theexcavationshouldprovideaminimumof48inches(1,200mm)whenusingChance™No-WrenchScrewAnchorstoallowforroomtoproperlyinstallthescrewanchors.Theactualexcavationsizeshallbedeterminedbytheinstaller.RefertoInfiltratorIM-SeriesTankInstallationInstructionsforadditionalexcavationprocedures.
Concrete-filled Half Pipe ConstructionConcrete-filledhalfpipeshallbesupportedwithsoilorotherstabilizingmeans below the pipe haunches prior to concrete placement. The stabilization shall prevent the pipe from rolling during placement and curing oftheconcrete.Concreteshallbeallowedtocureforaminimumofoneday prior to tank backfilling.
Placement of Deadmen and AnchorsConcretedeadmananchorsaretobeinstalledatthebottomofthetankexcavation,paralleltothelongaxisofthetank(seeFigure3).Figure 3: Plan View
The deadmen should be placed close to, but not touching, the tank on both sides of the tank to allow the placement of backfill between the deadman anchorandtanksidewall(seeFigure4).
Figure 4: Section View
Helical anchors should be installed so that the eye loop is level with the bottomofthetankexcavation.Theymustbeinlinewiththetankmodelstrappinglocations(seeFigure5)orliftinglugs,asappropriate.Anchorsmust also be installed at such a distance from and angle to the tank sothatthestrappingiswithin5°ofalignmentwiththeanchorshaftpermanufacturer’srecommendations.
PROVIDE ADEQUATE SPACE FORBACKFILL PLACEMENT BETWEENDEADMAN ANCHOR AND TANK
STRAPPING(TYPICAL)
DEADMANANCHOR
STRAPPING
DEADMANANCHOR(TYPICAL)
STRAPWIDTH
6" MIN EXTENSION 6" MIN EXTENSION
TANK030315
IM1530
IM-540
IM-1060
Figure 5: Strap Positioning
