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City of Everett Public Works Department | September 26, 2024 Page 2 <br /> File No. 00661-128-03 <br />This task also includes services for the AMS credit ledger management including agency negotiations, an <br />agency site visit, coordination and presentation of results and methods. Agency negotiations and <br />discussions will be toward the goal of project closeout following completion of the Year 7 monitoring <br />documentation. <br />TASK 200 – DRONE DATA COLLECTION <br />An aerial photograph and elevation point data collection of the AMS will be taken by drone during a low tide <br />of -2 feet North American Vertical Datum of 1988 (NAVD88) or lower to capture the extents of channel, <br />mudflat and vegetated areas. Elevation point data collection accurate to an inch will be collected to develop <br />site contours and will be verified by collecting elevation data using handheld global positioning system <br />(GPS) units on the ground at strategic locations. The aerial low tide photograph will be georeferenced and <br />used to inform mapping the size and distribution of the vegetation communities, mudflat and tidal channels <br />based on digital processing of their visual signatures. <br />A second aerial photograph of the entire AMS will be taken by drone during a high tide at or above +6 feet <br />NAVD88 to capture extents of tidal inundation at approximate elevation of estuarine wetlands. This <br />elevation is the approximate upward limit of where estuarine wetlands were previously documented by <br />Snohomish County (County) and the City. The aerial high tide photograph, along with point data collected <br />during the low tide drone flight, will be georeferenced and used to inform the area of wetlands based on <br />digital processing of the visual signatures of water surface and elevation. <br />Drone data will be primarily used to address AMS Performance Standards (PS’s): 1-1, 1-2 and 1-5. <br />TASK 300 – FIELD DATA COLLECTION: VEGETATION, WETLAND AND HABITAT DATA <br />During a consolidated field effort, the following data will be collected: <br />Vegetation Transects <br />To document species cover and richness (i.e., number of different species) across the approximately <br />8,550 linear feet of the AMS, vegetation cover and species richness will be sampled at 220, 1 meters <br />squared (m2) quadrate locations along 22 transects that bisect the AMS. A baseline transect will be placed <br />parallel along the center of the AMS and the location of the first bisecting transect will be randomly selected <br />from within the dike breach area. Each subsequent transect will be spaced across the AMS to complete <br />22 total transects. Each transect will have 10 quadrat samples spaced equally across the transect so <br />sampling spans the waterward, center and landward portions of the AMS. Each quadrate will be 1 m2 in <br />size. The percent cover of plant species within each quadrate occurring within delineated wetland and <br />aquatic habitats will be recorded, and quadrates occurring within upland habitat will be visually assessed <br />for development of wetland characteristics and qualitative invasive species presence (Snohomish County <br />Class A and Class B designated species, as defined in PS 1-6). Plant species with less than 5 percent cover <br />will be recorded as “trace” cover. <br />A handheld GPS unit will be utilized in navigating to each sampling location, and points will be recorded at <br />each vegetation sample. This method will allow for an unbiased sample, providing greater coverage of the <br />AMS, while also minimizing sampling-related impacts on vegetation development (i.e., repeated trampling <br />within the same plots). Photo points will be collected from the end point of each transect looking towards <br />the sampled vegetation.