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EXH AR026409: Wetland Mitigation Calculations — Vacca Farm

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Sea-Tac Airport
Third Runway
PCHB
Box 10

This document outlines wetland mitigation calculations for the Vacca Farm site, detailing compensation actions such as wetland restoration and enhancement across various locations including Lora Lake and prior converted croplands. Adjustments were made to credit acreages based on state ecology findings and documentation gaps; for example, the 6.60-acre converted cropland credit was reduced to 3.30 acres because the state identified those areas as existing wetlands requiring enhancement ratios rather than restoration ratios. In total, the site's original 10.48 credit acres were adjusted down to 5.61 acres after accounting for these regulatory and documentation considerations.

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Notes

Attachment E from the PCHB Third Runway EIS administrative record (AR 026409). Wetland mitigation calculations for Vacca Farm, drawn from NRMP data tables (Parametrix, 2001). Details compensation actions including wetland restoration at Lora Lake (fill removal, 1.0 acre) and prior converted croplands (6.60 action acres, adjusted to 3.30 due to Washington State Ecology documentation of regulated wetlands). Wetland enhancement at ratio 1:2 covers Wetlands A1, A1a, A2, A3, A4 (1.59 acres), FW 1,2,3,9,10,11 (0.73 acres), Lora Lake Shoreline (0.32 acres), and Lora Lake aquatic habitat (3.06 action acres, adjusted to 0.0 because Lora Lake is not identified as wetland in Port of Seattle documents and no NRMP text or landscape plans exist for the proposed lake enhancement). Total Vacca Farm credit acres: 10.48 unadjusted, 5.61 adjusted.

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