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  <xsd:element name="QualifiedCashOrDeferredArrangementMember" id="wldn_QualifiedCashOrDeferredArrangementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DefinedContributionPlanEmployerMatchingContributionAgeOfEmployees" id="wldn_DefinedContributionPlanEmployerMatchingContributionAgeOfEmployees" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="TopTenCustomersMember" id="wldn_TopTenCustomersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ContractWithCustomerAssetAndConstructionContractorReceivableRetainageAfterAllowanceForCreditLossCurrent" id="wldn_ContractWithCustomerAssetAndConstructionContractorReceivableRetainageAfterAllowanceForCreditLossCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="AccruedAccountingAndTaxesCurrent" id="wldn_AccruedAccountingAndTaxesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AccruedRebatesAndOtherCurrent" id="wldn_AccruedRebatesAndOtherCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="DefinedContributionPlanEmployerMatchingContributionMaximumAmountPerEmployee" id="wldn_DefinedContributionPlanEmployerMatchingContributionMaximumAmountPerEmployee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="VariableInterestEntityPercentageOfCostsReimbursed" id="wldn_VariableInterestEntityPercentageOfCostsReimbursed" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="CreditAgreement2023Member" id="wldn_CreditAgreement2023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="SouthernCaliforniaEdisonAndClarkCountySchoolDistrictMember" id="wldn_SouthernCaliforniaEdisonAndClarkCountySchoolDistrictMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="EnicaEngineeringPllcMember" id="wldn_EnicaEngineeringPllcMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AlphaInspectionsIncMember" id="wldn_AlphaInspectionsIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NoncashOrPartNoncashAcquisitionContingentConsideration" id="wldn_NoncashOrPartNoncashAcquisitionContingentConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="EarningsBeforeInterestTaxesDepreciationAndAmortization" id="wldn_EarningsBeforeInterestTaxesDepreciationAndAmortization" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsExcludingRightOfUseAssetsFiniteLivedIntangibleAssetsAndGoodwill" id="wldn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsExcludingRightOfUseAssetsFiniteLivedIntangibleAssetsAndGoodwill" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsRightOfUseAssets" id="wldn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsRightOfUseAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesExcludingLeaseLiabilities" id="wldn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesExcludingLeaseLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesLeaseLiabilities" id="wldn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesLeaseLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationProFormaInformationIncomeLossFromContinuingOperationsOfAcquireeSinceAcquisitionDateActual" id="wldn_BusinessCombinationProFormaInformationIncomeLossFromContinuingOperationsOfAcquireeSinceAcquisitionDateActual" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AlternativePowerGenerationIncMember" id="wldn_AlternativePowerGenerationIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="BusinessCombinationContingentConsiderationArrangementsEarnoutPaymentsMaximumPayout" id="wldn_BusinessCombinationContingentConsiderationArrangementsEarnoutPaymentsMaximumPayout" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationContingentConsiderationArrangementsEarnoutPaymentsEarnoutPeriod" id="wldn_BusinessCombinationContingentConsiderationArrangementsEarnoutPaymentsEarnoutPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuableClosingAveragePricePerShareTradingDaysPrecedingClosing" id="wldn_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuableClosingAveragePricePerShareTradingDaysPrecedingClosing" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLeaseLiabilityNoncurrent" id="wldn_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLeaseLiabilityNoncurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AmortizationOfDebtPercentageAnnually" id="wldn_AmortizationOfDebtPercentageAnnually" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LineOfCreditFacilityMaximumBorrowingCapacityBorrowerMayRequestAggregateCommitmentMaximumCommitmentAmount" id="wldn_LineOfCreditFacilityMaximumBorrowingCapacityBorrowerMayRequestAggregateCommitmentMaximumCommitmentAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LineOfCreditFacilityMaximumBorrowingCapacityBorrowerMayRequestAggregateCommitmentMaximumCommitmentLastTwelveMonthsAdjustedEbitdaRatio" id="wldn_LineOfCreditFacilityMaximumBorrowingCapacityBorrowerMayRequestAggregateCommitmentMaximumCommitmentLastTwelveMonthsAdjustedEbitdaRatio" type="xbrli:pureItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="AlternativePowerGenerationIncAlternativePowerGenerationIncAndEnicaEngineeringPllcMember" id="wldn_AlternativePowerGenerationIncAlternativePowerGenerationIncAndEnicaEngineeringPllcMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AmortizationOfDebtPercentageAnnuallyForSecondAndThirdYears" id="wldn_AmortizationOfDebtPercentageAnnuallyForSecondAndThirdYears" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="CreditAgreement2023PriorCreditAgreement29September2023Member" id="wldn_CreditAgreement2023PriorCreditAgreement29September2023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025Member" id="wldn_CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023PriorCreditAgreement29September2023TermLoanMember" id="wldn_CreditAgreement2023PriorCreditAgreement29September2023TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023PriorCreditAgreement29September2023RevolvingCreditFacilityMember" id="wldn_CreditAgreement2023PriorCreditAgreement29September2023RevolvingCreditFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025TermLoanMember" id="wldn_CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025RevolvingCreditFacilityMember" id="wldn_CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025RevolvingCreditFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025DelayedDrawTermLoanMember" id="wldn_CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025DelayedDrawTermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025LetterOfCreditMember" id="wldn_CreditAgreement2023AmendedAndRestatedCreditAgreement05May2025LetterOfCreditMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CreditAgreement2023PriorCreditAgreement29September2023LetterOfCreditMember" id="wldn_CreditAgreement2023PriorCreditAgreement29September2023LetterOfCreditMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RepaymentsOfLinesOfCreditRetirePriorCreditAgreement" id="wldn_RepaymentsOfLinesOfCreditRetirePriorCreditAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationConsiderationTransferredPurchasePriceSubjectToHoldbacksAndAdjustments" id="wldn_BusinessCombinationConsiderationTransferredPurchasePriceSubjectToHoldbacksAndAdjustments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AccountingStandardsUpdate202503Member" id="wldn_AccountingStandardsUpdate202503Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AccountingStandardsUpdate202505Member" id="wldn_AccountingStandardsUpdate202505Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AccountingStandardsUpdate202506Member" id="wldn_AccountingStandardsUpdate202506Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesBacklogAndGoodwill" id="wldn_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesBacklogAndGoodwill" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesCustomerRelationshipsAndTradename" id="wldn_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesCustomerRelationshipsAndTradename" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesIncreaseDecreaseInAmortizationExpense" id="wldn_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesIncreaseDecreaseInAmortizationExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesCustomerRelationshipsAndNoncurrentAssets" id="wldn_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesCustomerRelationshipsAndNoncurrentAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesBacklogTradenameGoodwillAndLiabilities" id="wldn_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangiblesBacklogTradenameGoodwillAndLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
</xsd:schema>
