TECHNICAL MEMORANDUM

Transcription

1 1111 Main Street, Suite 300, Vancouver, Washington / / Fax TECHNICAL MEMORANDUM DATE: TO: FROM: RE: City of Vancouver Dustin Day, PWS Wetlands & Habitat Assessment Clark Public Utility Substation Port of Vancouver, USA Introduction The purpose of this technical memorandum is to report the findings of a site assessment that investigated the presence of potential wetland and habitat areas on the proposed site of a Clark Public Utilities substation. The substation is proposed to be located on the undeveloped portion of the existing Clark County Jail Work Center site (parcel No ), located west of NW Gateway Avenue, at the Port of Vancouver, USA (port), in the City of Vancouver (City), Washington. The substation project is proposed to serve existing and future customers. The project will build a power transformation (115 kv to kv) substation on an approximately 1.1 acre portion of the project site located to the southeast of an existing Bonneville Power Administration (BPA) electrical transmission facility and the Clark Public Utilities River Road Generating Plant. Power will connect into the proposed substation from the BPA electrical transmission facility through the River Road Generating Plant via overhead lines transmitting 115 kv power. At the substation, this power will be transformed to kv and distributed via an underground duct bank from the substation to Clark Public Utilities customers at the port and other customers located in the vicinity of the proposed substation. Two BergerABAM natural resource scientists visited the site on April 12, The assessment took place north and east of the existing jail facility building, within the NE ¼ of Section 19 and NW ¼ of Section 20, Township 2 North, Range 1 East, of the Willamette Meridian (WM). Before the site assessment, a BergerABAM scientist reviewed online databases to ascertain whether any environmentally sensitive areas had been mapped on or adjacent to the site. The databases included soils (US Department of Agriculture [USDA] Natural Resources Conservation Service

2 Page 2 [NRCS]); wetlands (US Fish and Wildlife Service [USFWS] National Wetland Inventory [NWI]); priority habitats (Washington Department of Fish and Wildlife [WDFW] Priority Habitats and Species [PHS]); and Clark County GIS databases for wetland and habitat mappings. Site Description The undeveloped portion of the Jail Work Center site is generally level, south and east of the existing facilities, and slopes gently down in the north and far northeast portions of the site. The railroad system within the port forms the northern boundary of the site and NW Gateway Avenue forms its eastern boundary. Two forested areas exist within the study site, one in the northwest corner and one in the northeast corner. Both forested areas are dominated by deciduous trees with a sparse understory of deciduous and evergreen trees. The southeast portion of the site has been planted with rows of evergreen trees. The remaining areas of the study site are covered in non native, weedy grass and herbaceous species typical of maintained lawns. Wetland Findings The guidance used during the site visit to assess the potential presence of wetlands came from the US Army Corps of Engineers (USACE) Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (USACE 2010). For a wetland determination to be verified there must be positive indicators of three wetland parameters: hydrophytic vegetation, hydric soil, and wetland hydrology. Clark County s Digital GIS mapping has indicated the potential presence of wetlands within the site, as defined in the Vancouver Municipal Code (VMC ). In addition, NWI mapping of the assessment area indicated the presence of three wetlands within the northern portions of the site. The mapped wetlands included two palustrine forested temporarily flooded (PFOA) wetlands and one palustrine emergent seasonally flooded (PEMC) wetland. The NWI map was based on color infrared aerial photographs (scale of 1:58,000), with selected onsite reconnaissance to confirm the interpretations. However, it should be noted that NWI maps are created by interpreting aerial photographs and topographic maps and are not meant to represent the extent of jurisdictional wetlands. The temporarily flooded modifier of the PFOA wetland designation and the seasonally flooded modifier of the PEMC are defined by NWI as: Temporarily Flooded Surface water is present for brief periods during the growing season, but the water table usually lies well below the soil surface for most of the growing season. Plants that grow both in uplands and wetlands may be characteristic of this water regime. Seasonally Flooded Surface water is present for extended periods especially early in the growing season, but is absent by the end of the growing season in most years. The water table after

3 Page 3 flooding ceases is variable, extending from saturated to the surface to a water table well below the ground surface. During the site visit, BergerABAM scientists traversed the study area by foot to identify areas of potential wetlands. Scientists took soil samples in the lowest elevations of the site, specifically along the northern and northeastern boundary of the site and in a small depression along its eastern boundary. Soil characteristics were recorded, along with hydrologic indicators and existing vegetation. The site contained two dominant vegetation communities: forested and herbaceous. Black cottonwood (Populus balsamifera L. ssp. trichocarpa FAC) dominated the forested community while velvetgrass (Holcus lanatus FAC), annual bluegrass (Poa annua FAC), common dandelion (Taraxacum officinale FACU), hairy cat s ear (Hypochaeris radicata FACU), and various moss species dominated the vegetation within the herbaceous community. Both vegetative communities contained a mixture of upland and wetland species, but neither community met the hydrophytic vegetation criteria as described in the delineation manual. Soils mapped on the site were Pilchuck fine sand, 0 to 8 percent slopes (PhB), which is considered a non hydric soil (NRCS 2012 and Clark County 2012). Soils examined in the northern and eastern portions of the site were generally consistent with the mapped soil description. Soils on the level portion of the site to the east of the Jail Work Center were generally lighter in chroma and value than the mapped soils. In addition, none of soil samples taken within the site exhibited characteristics in the soil (redoximorphic features) that would indicate any extended periods of soil saturation. Therefore, the scientists determined that the study site did not contain hydric soil characteristics. The site visit was conducted under typical early spring conditions and the soils were observed to be generally well drained and did not exhibit signs of primary wetland hydrology. However, the sample plot located in the lowest area along the northern boundary had water within the pit at 10 inches below the soil surface. This one plot had a positive indicator for wetland hydrology. However, neither the hydric soil indicator nor the wetland vegetation indicator was observed at this plot. Therefore, a wetland determination was not made at this sample plot or any other location within the study site. Habitat Findings Guidance used during the site visit for assessing the potential presence of habitats came from the WDFW 2008 Priority Habitat and Species List (WDFW 2008) and the fish and wildlife habitat conservation areas section of the City s critical areas ordinance (VMC ). Based on the County s Digital GIS mapping, riparian priority habitat as defined in the Vancouver Municipal Code (VMC ) is potentially present on the site. However, the

4 Page 4 WDFW PHS on the web GIS database does not identify any riparian priority habitat. It should be noted that priority habitat and species (PHS) maps are created by interpreting aerial photographs and topographic maps coupled with limited field verifications, and are not meant to represent the extent of all PHS. Due to the discrepancy in GIS databases, BergerABAM scientists referred to the definition of a riparian priority habitat to determine if priority habitat exists within the study site. The riparian PHS is defined by WDFW as: The area adjacent to flowing or standing freshwater aquatic systems. Riparian habitat encompasses the area beginning at the ordinary high water mark and extends to that position of the terrestrial landscape that is influenced by, or that directly influences, the aquatic ecosystem. In riparian systems, the vegetation, water tables, soils, microclimate, and wildlife inhabitants of terrestrial ecosystems are often influenced by perennial or intermittent water. Simultaneously, adjacent vegetation, nutrient and sediment loading, terrestrial wildlife, as well as organic and inorganic debris influence the biological and physical properties of the aquatic ecosystem. Riparian habitat includes the entire extent of the floodplain and riparian areas of wetlands that are directly connected to stream courses or other freshwater. During the site visit, BergerABAM scientists traversed the study area by foot to identify areas of potential riparian habitat. This included determining whether the site has a direct influence on the Columbia River or if the Columbia River influences any habitat on site. The first part of the definition explains that the riparian habitat extends from the ordinary high water mark to the position in the terrestrial landscape that is influenced by, or directly influences, the aquatic ecosystem. While the site is mapped as being within the 100 year floodplain, the extensive development over the years of the port properties that surround the site constructed a dike system that substantially limits the Columbia River from flooding the site. In addition, the site is approximately 1,200 linear feet from the Columbia River and over 1,000 linear feet from the floodplain area associated with Vancouver Lake. Therefore, based on this information BergerABAM scientists believe that the site does not contain habitat that is influenced by, nor does it influence, the aquatic ecosystem of the Columbia River. The second part of the definition discusses how adjacent vegetation, sediments, wildlife, and debris influence the biological and physical properties of the aquatic ecosystem. As mentioned above, the site is approximately 1,200 feet from the aquatic ecosystem and any organic or inorganic debris, vegetation, or nutrient or sediment loading would not influence the biological or physical properties of the aquatic ecosystem. Therefore, because the site meets neither part of the definition, it is the opinion of the natural resources scientists that priority riparian habitat does not exist on the site and should not be mapped by the Clark County GIS database.

5 Page 5 Conclusions Both the wetlands section (VMC (A)(1)) and the fish and wildlife habitat conservation areas section (VMC (A)(1)) of the City code state that final designations shall be based on site conditions and other available data or information. Therefore, based on the findings discussed above, the site is not subject to the provisions of either section of the code. It should be noted that the results of this wetland and habitat assessment were determined using the most appropriate field techniques and best professional judgment of the natural resource scientists. The USACE, Washington Department of Ecology, WDFW, and the City have the final authority to determine the boundaries and jurisdictional status of wetlands and habitats under their appropriate jurisdiction.

6 Page 6 References City of Vancouver Chapter Critical Areas Protection Ordinance, City of Vancouver Development Code. Vancouver, Washington. October 1, Clark County Clark County GIS database. US Army Corps of Engineers (USACE) Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), ed. J.S. Wakeley, R.W. Lichvar, and C.V. Noble. ERDC/EL TR Vicksburg, MS: US Army Research and Development Center. US Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey Geographic (SSURGO) database for Clark County, Washington. Spatial data source NRCS 8 and tabular data source NASIS. US Fish and Wildlife Service (USFWS) National Wetlands Inventory (NWI). Online Wetlands Mapper. Washington Department of Fish and Wildlife (WDFW) Priority Habitats and Species on the Web; Interactive Mapping Tool. Washington Department of Fish and Wildlife (WDFW) Priority Habitat and Species List. Olympia, Washington. 177 pp.