1.0 INTRODUCTION altemate,less costlyconcepts to theinsulated steelwater A studywasundertaken to investigate andseweraccess vaultcurrentlyadoptedby theGovemnentofthe NorthwestTerritoiesfor water and sewermain servicingin theNWT. buied Altemativeconceptswere developedand assessed using the Kepner-Tregoe methodof DecisionAnalysis.Thismethodrequiresthata hierarchyofobjectivesbeestablished, against whichthe altemateconceptsareevaluated. The currentdesignwhich utilizesa corDmoninsulatedsteelaccessvault for bothwaterand sewersystems is theresultofnearly20 yearsofdesignevolution.Prcblemswhichcomrnonly vaultsincludedwaterinfiltration occunedwith the earliersystems ofwater andseweraccess insulation,difficultyof intothevaults,physicalandmoistuedanageto theintemalurethane access to appurtenances, andfreezebreakage ofpiping andappurtenances. The insulatedsteelaccessvaultwhich is presentlyused,hasrectifiedall oftheseproblems with the previousdesigns.However,thesevaultsmay costin excessof$39,000. associated ofall fittingsandappurtenances, butdoesnotinclude Thiscostincludes supplyandinstallation ofthe mobilizationand demobilization.The costofthe accessvaultsmay represent30o% contractp ce for the pipedutilitiessystem. 2.0 METHODOLOGY The data collectionwas basedon a surveyof accesssystemsin Alaska and the Yukon. otherthanwaterandsanitationdepartments suchastelephone utilities Govemmentagencies were also co[tacted. None of the groupscontactedhad developeda specialdesignfor permafiostareas;rather,they usedstandardprefabricatedconcreteor metal sections. waterandsewermainswâ‚Źredevelopedthroughgroup Thealtemativeconceptsfor accessing in coldregion,municipal,andmechanical engineering. discussions ofUMA staffexperienced ofthe AdditionalinputwasobtainedfromtheMunicipalandCommunityAffairs Department NWT eovemment. 3.0 ALTERNATIVE CONCEPTS 3.1
AccessFrom Wilhin A Structure
withinthisgroup,assumnrarized in thefollowingTable1, maybe Thealtemative concepts accessed furtherclassifiedashavingfittingsandappurtcnanccs in a belowgroundstructure, andfittingsandappu enances accessed in an abovegroundstructufe.