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  <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="TermLoanMember" id="wldn_TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RevolvingCreditFacility2023Member" id="wldn_RevolvingCreditFacility2023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LongTermDebtGrossFiscalYearMaturityYearOne" id="wldn_LongTermDebtGrossFiscalYearMaturityYearOne" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LongTermDebtGrossFiscalYearMaturityYearTwo" id="wldn_LongTermDebtGrossFiscalYearMaturityYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="EnicaEngineeringPllcMember" id="wldn_EnicaEngineeringPllcMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ScheduleOfContractualObligationFiscalYearMaturityScheduleTableTextBlock" id="wldn_ScheduleOfContractualObligationFiscalYearMaturityScheduleTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="AmortizationOfDebtPercentageForSecondAndThirdYears" id="wldn_AmortizationOfDebtPercentageForSecondAndThirdYears" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LineOfCreditFacilityContingentIncreaseAggregateMaximumBorrowingCapacity" id="wldn_LineOfCreditFacilityContingentIncreaseAggregateMaximumBorrowingCapacity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SouthernCaliforniaEdisonMember" id="wldn_SouthernCaliforniaEdisonMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LetterOfCredit2023Member" id="wldn_LetterOfCredit2023Member" 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="AccruedLiabilitiesBusinessCombinationOtherWorkingCapitalAdjustmentsAndHoldbacksCurrent" id="wldn_AccruedLiabilitiesBusinessCombinationOtherWorkingCapitalAdjustmentsAndHoldbacksCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationConsiderationTransferredOtherWorkingCapitalAdjustmentsAndHoldbacks" id="wldn_BusinessCombinationConsiderationTransferredOtherWorkingCapitalAdjustmentsAndHoldbacks" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" 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:schema>
