Volume 2: Draft Gorst Planned Action Environmental Impact Statement

GORST PLANNED ACTION EIS | AFFECTED ENVIRONMENT, SIGNIFICANT IMPACTS, AND MITIGATION MEASURESAlternatives: Future Growth, it is assumed that most development outside of city limits and designated UGAswould be associated with residential dwellings, with increased construction over the next 20 years. Construction ofnew buildings, structures, and infrastructure would result in ground disturbance within affected areas andpotential effects to historic built environment resources older than 50 years. Removal of trees and othervegetation within these areas could also lead to reduced infiltration and erosion of exposed soils from affectedsites. Ground disturbance and increased construction may result in the potential loss of significant culturalresources. Under all the alternatives, risks of disturbance to significant cultural resources associated withdevelopment and other ground disturbing activities would be greatest on within those areas identified as HighProbability Areas (Table 3.10-5 Development and Construction Activities in High and Moderate Probability AreasDiscussion). Preconstruction cultural resources inventories and evaluations within the High Probability Areas wouldhelp minimize these impacts to varying degrees.One significant cultural resource is known to exist in the Study Area: Site 45KP109. Future development in theStudy Area would not affect known cultural resources unless they occur on the same parcels where Site 45KP109 islocated or results in the discovery of a previously unknown resource. The potential for impacts on unknowncultural resources cannot be accurately measured at this time because the Study Area has not been inventoried forsignificant cultural resources. The only cultural resources studies that have been completed in the Study Areainclude those listed in Table 3.10-1 Previously Studied Cultural Resources within the Study Area 1. Other portions ofthe Study Area have not been surveyed for cultural resources, including archaeological sites, built environmentresources, and TCPs. Portions of the Study Are have been identified as having high probability for containingsignificant cultural resources.Both Alternatives 2 and 3 accommodate future growth in the Study Area, which could occur on any parcel withinthe Study Area, including those areas determined to have High Probability and Moderate Probability, andtherefore have the potential to affect unknown cultural resources. Therefore, potential impacts on unknowncultural resources would be the same under all studied alternatives, although the rate and timing of these impactswould vary. Implementation of mitigation measures would identify potential impacts on cultural resources reducethem to less than significant.Given that significant cultural resources are present within the Study Area and that High Probability Areas havebeen identified, future development would have the potential to impact these resources. It is assumed that underall alternatives, future development projects would receive the appropriate permits, and that buffers,development standards, and other mitigation measures pertaining to identifying and preserving significant culturalresources would be implemented.Gorst UGAUnder all alternatives, most impacts to cultural resources would occur within the Gorst UGA, where the majority ofplanned development would be focused. Within the UGA, development could occur within the 281 parcel acrespreviously discussed, although the types of development would vary by alternative. Additionally, it is unlikely thatall currently developed areas would be redeveloped within the next 20 to 30 years. Potential impacts associatedwith development and construction activities within the UGA would be similar to those described for thewatershed. The potential for loss of significant cultural resources would be present, including archaeological sites,historic built environment resources, and TCPs, all of which would have the potential to be minimized, to varyingdegrees by conducting preconstruction cultural resources inventories and evaluations within the High ProbabilityAreas and implementing mitigation measures.Prior to initiating development and construction activities in High and Moderate Probability Areas (Table 3.10-5Development and Construction Activities in High and Moderate Probability Areas Discussion), it is recommendedthat intensive surveys of the High and Moderate Probability Areas be conducted and evaluations prepared todetermine which of those resources would be considered significant for the purposes of SEPA and listed in theWHR and/or the NRHP. Intensive surveys would provide economies of scale in evaluating each survey area, ratherDraft | June 2013 3-140