illpromoteself-ur.Stageconstruction:Itisoftenpossibleandinsomecasesnecessary,toconstructthedamembankmentinstages.Factorsdictatingsuchaprocedureare:①awidevalleypermittingtheconstructionofthediversionoroutletworksandpartoftheembankmentatthesametime;②aweakfoundationrequiringthattheembankmentnotbebuilttoorapidlytopreventoverstressingthefoundationsoils;③awetborrowareawhichrequiresaslowcasesitmayconstructiontopermitanincreaseinshearstrengththroughconsolidationofthefill.Insomecasesitmaybenecessarytoprovideadditionaldrainageofthefoundationorfillbymeansofsanddrainwellsorbymeansofhorizontalperviousdrainageblankets.Embankmentsoils:Mostsoilsaresuitableforuseforembankmentconstruction,however,therearephysicalandchemicallimitations,soilswhichcontainexcessivesaltsorothersolublematerialsshouldnotbeused.ont