Appendix E Preliminary Jurisdictional Wetland Delineation Report, JYL 2008

Transcription

1 Appendix E Preliminary Jurisdictional Wetland Delineation Report, JYL 2008

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3 PRELIMINARY JURISDICTIONAL WETLAND DELINEATION REPORT A portion of USS 3819 and 2664: Horton Lot and Statter Harbor Juneau, Alaska Prepared by: Jensen Yorba Lott, Inc. June 16, 2008

4 GENERAL The site is located in Juneau, Alaska adjacent to Auke Bay. The site includes the land to the immediate west of the existing Statter Harbor facilities to the eastern edge of Bay Creek. The subject property is between Glacier Highway to the north and the Auke Bay tidelands to the south. The site includes USS 3819 ATS 121 and 756 as well as USS 2664 Lot 5 and the tidelands to the south of Lots 4 and 5. The property is located on Alaska Quad map Juneau B-2. The center of the site has a latitude of 58 degrees N and a longitude of 134 degrees W. All property is owned by the City and Borough of Juneau who is the client. ATS 121 and a portion of ATS 756 includes the Horton Lot and the surrounding Auke Bay tidelands and Bay Creek drainage. The Horton Lot is the overflow trailer parking for Statter Harbor. Lot 5 includes a small park with a shelter and the adjacent tidelands. The tidelands to the south of Lot 4 (a private residential lot) is also included in the project area. Vicinity map of project area. Source: Modified Google Earth mapping. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Jensen Yorba Lott, Inc. Preliminary Jurisdictional Wetland Determination Report Page 1

5 The purpose of this Preliminary Jurisdictional Wetland Determination Report is to define the extent of the wetlands within the project area. This will assist the City and Borough of Juneau to explore options for expanding its Statter Harbor Facilities. This Determination Report is based on best professional judgment utilizing data gathered during site visits, from aerial and topographic maps, and existing wetland and soils maps. The wetland delineation was developed within the project area in accordance with the US Army Corps of Engineers 1987 Wetlands Delineation Manual and the 2008 Regional Supplement to the Corps of Engineering Wetlands Delineation Manual: Alaska Region. The delineations shown within this report are approximate and make all efforts to portray the existing conditions as accurately as possible. View of the site looking north from Statter Harbor. The blue roof structure is the park shelter and the area to the left surrounded by alders and willows is the Horton Lot parking. DESCRIPTION The project area is located to the west of the existing Statter Harbor facilities and includes the Horton Lot, associated tidelands of Auke Bay, and the east portion of the Bay Creek drainage. The project area measures 2.44 acres. The area is comprised of four distinct ecosystems. A portion of the property is found below the ordinary high water mark and is classified as a deep water subtidal area and waters of the United States. The second ecosystem includes the low lying areas found in the estuarine system just above the ordinary high water mark and is a typical intertidal ecosystem affected by storm events and extreme high tides and comprised of sand and gravel over organic soils populated by sedges, grasses and other intertidal plants. Two creek drainage systems are found within the project area and include Bay Creek to the west and a small wide spreading drainage through Lot 5 adjacent to the park shelter. These areas include organic soils and shallow water tables some with surface water and populated mostly by herbaceous plant material. The forth ecosystem includes a large portion of the site that has been modified by human activities. This disturbance includes the deposit (ten to twenty foot depth) of shot rock for the creation of the Horton parking lot. Fill was also deposited at approximately a three foot depth to create a construction pad for the park shelter and the creation of an access road to the shelter. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Jensen Yorba Lott, Inc Preliminary Jurisdictional Wetland Determination Report Page 2

6 Much of these deposits were likely placed over wetlands. Total fill area is approximately 1.36 acres. The parking lot has no or limited plant communities and the park shelter area is populated by herbaceous plant material. The rock slopes of the fill areas are populated by willows, alders and herbaceous plant material. The Horton Lot is comprised of 10 to 20 foot depth of engineering fill and serves as overflow parking for the harbor. The landforms of most of the site are level with slopes ranging from 3-10%. Areas with the steepest slopes include the rock fill slopes for the parking area (50%) and the near vertical slopes cut by Bay Creek through the intertidal system. Portions of the subtidal zone have energy dissipaters located just below ordinary high water mark that are comprised of large boulders and concrete set into the subtidal area. The area just behind the boulders has likely been filled naturally with sand and gravel by storm and tidal activity. Looking north towards Bay Creek from the intertidal area of the Horton Lot. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 3

7 As part of the overall planning and permitting activity for the expansion of Statter Harbor, Jensen Yorba Lott, Inc. was retained for assisting in permitting and planning including competing this preliminary jurisdictional wetland delineation report for the project area. Christopher Mertl, landscape architect with Jensen Yorba Lott, Inc. carried out the wetland delineation. The site work for the delineation was executed on May 28, Bay Creek looking towards the project area and Glacier Highway. The weather for the spring of 2008 could be characterized as cooler temperatures and slightly higher than average rainfall. This spring weather delayed minday (beginning of growing season) by two weeks. The delineation was carried out under mostly clear skies with temperatures in the mid 60 s. Several days of precipitation preceded the field work. DELINEATION AREA The delineation area is located to the immediate west of the existing Statter Harbor facilities to the eastern edge of Bay Creek, between Glacier Highway and the Auke Bay tidelands to the south. The site includes USS 3819 ATS 121 and 756 as well as USS 2664 Lot 5 and the tidelands to the south of Lots 4 and 5. The total area is approximately 2.44 acres with approximately 1.36 acres of the site being disturbed with a significant depth of engineering fill. The U.S. Fish and Wildlife Service's National Wetlands Inventory classifies several portions of the project area as wetlands. These areas include the estuarine subtidal zone, a portion of the low lying intertidal area. The National Wetlands Inventory Mapping Code for the subtidal zone is E1UBL and can be summarized as [E] Estuarine, [1] Subtidal, [UB] Unconsolidated Bottom, [L] Subtidal. The intertidal areas and the area around the park shelter has a mapping code of E2AB/USN which can the characterized as [E] Estuarine, [2] Intertidal, [AB] Aquatic Bed/ [US] Unconsolidated Shore, [N] Regularly Flooded. The National Wetland Inventory Mapping (below) for this area is extremely rough and this may be due to the amount of fill activity that has occurred in the Statter Harbor area that makes translation to this map difficult. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 4

8 U.S. Fish and Wildlife Service's National Wetlands Inventory in the vicinity of the project area. Source: USF&WS: Division of Habitat and Resource Conservation. The Soils of the Juneau Area completed by the USDA Soil Conservation Service in 1974 indicates the project area has a Wadleigh soil classification with a WaB mapping unit. The Wadleigh series consists of somewhat poorly drained soils that occur on lower hills and mountains. These soils are formed in very gravelly loamy materials underlain by firm glacial till that impedes internal drainage. They have a mat of forest litter, a thin grayish brown layer, and dark reddish brown to dark yellow brown layers above the firm substratum. The vegetation is a forest of western hemlock and scattered Sitka spruce. The WaB mapping unit is a gravelly silt loam with slopes of 3-7%. This description represents a portion of the site however tidal and storm events in the intertidal system as well as disturbance by man have likely altered these characteristics throughout most of the site. Areas in the intertidal system that have not been altered with engineering fill typically consist of a thin O horizon over a silt, sand and cobble layer (due to tidal and storm activity) underlain with a histic epipedon hydric soil, and a gravel and cobble base layer. Further upland (around the park shelter and along Bay Creek) consists of a histosol hydric soil associated with a high water table. All disturbed areas consist of a 3 to 20 foot depth of engineering fill over an undetermined base. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 5

9 The project area is found on the City and Borough of Juneau s Wetland Mapping B-28 and shows no wetlands within or in the immediate vicinity of the site. The lower segment of Bay Creek is listed by the Alaska Department of Fish and Game as an anadromous fish stream. Looking south across the site from the Horton Lot towards Statter Harbor. Residential property is located to the left of the photo. METHOD OF DELINEATION The delineation followed the guidelines in the US Army Corps of Engineers Wetland Delineation Manual, 1987 and the 2008 Regional Supplement to the Corps of Engineering Wetlands Delineation Manual: Alaska Region. Preliminary analysis included review of aerial photographs, topographic maps, existing wetland maps (including local and National sources), soil mapping, and interviews with those familiar with the project area. Field investigation included a site walk through to determine the variety of ecosystems and landscape types. Sample points were taken in each plant community in the project area and at regular intervals along the apparent ecosystem boundary. At each sampling point, the three indicators (hydrology, soils and vegetation) were observed and field noted on a Wetland Determination Data Form-Alaska Region. To meet the jurisdictional requirements for a wetland, all three indicators needed to be present. Photos were taken of each sampling point and the location indicated on a site plan. Stakes and flagging were installed in the field to allow the data to be transferred to a site survey by a licensed land surveyor. The wetland mapping was completed on June 5, 2008 by PN&D, Inc. and is found on page 12 of this report. Vegetation All plant species were recorded on the data forms for each sample plot. The absolute percentage of cover for each plant was listed and their corresponding indicator status Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 6

10 determined using the USDA Natural Resources Conservation Service, Wetland Indicator Plant Species. Categories are: Obligate Wetland (OBL), Facultative Wetland (FACW), Facultative (FAC), Facultative Upland (FACU) and Upland (UPL). The Prevalence Index for vegetation was calculated and those with an index of less than or equal to 3 represented the presence of hydrophytic vegetation. Soils Soils at each sampling point were hand dug and inspected to a depth of 20 or refusal, to determine the presence of hydric soil indicators. The depth of soil horizons was measured and the hue, value, chroma and texture were determined for each horizon. Hue, value, chroma and matrix were calculated using a Munsell Soil Color Chart. Hydrology Presence or absence of wetland hydrology was determined at each sampling point. The presence of standing water, saturated soils, and depth of free water was recorded. Other primary indicators such as presence of watermarks, drift lines, sediment deposits and drainage patterns were recorded when observed. Looking towards the park shelter (to left behind alders) and the residential buildings. Much of this area is wetlands. TYPICAL SAMPLING POINTS DATA This determination included thirteen (13) sampling points throughout the site and could be broken into seven distinct findings for vegetation, soils and hydrology. These are summarized as follows: Intertidal wetland, intertidal gleyed wetland, intertidal non-wetland, fill slope, stream meadow, saturated depression and fill area. Images and summaries of each are found on the following pages with the exception of the fill area which was comprised of engineering fill to a depth of greater than 28 inches from the surface and makes up the Horton Lot parking area. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 7

11 Typical sample pit found in intertidal systems that contained wetlands. Sample plots tended to be comprised of hydrophytic grasses and sedges, with a gravel, cobble, organic surface up to 12 deep covering a histic epipedon soil below. It is likely that tide and storm activity keeps the hydric soil below the surface. Soil profiles had a 5YR/2.5/1 hue, value and chroma. Water is present in the bottom of the sample pits. Shown is test pit #1. Typical sample pit found in intertidal systems that contained gleyed wetlands. Sample plots tended to be comprised of hydrophytic grasses and sedges, with an organic cover over a gleyed clay layer of greater than 18. Soil profiles had a Gley1/4/5G hue, value and chroma. Soils were saturated with water being present in the bottom of the sample pit. Shown is test pit #12. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 8

12 Typical sample pit found in intertidal systems that was not a wetland. Sample plots tended to be comprised of intertidal vegetation growing on a sand/silt/shale and cobble soil to a depth of 20 with no or little organics present. Despite being above ordinary high water mark tidal and wave action continues to deposit large sized material in these areas. No hydrology was present. Shown is test pit #8. Typical sample pit found on fill slope areas on the perimeter of the Horton Lot parking. Sample plots tended to be comprised of marginal hydrophytic vegetation including herbaceous materials, willows and alders growing on an organic loamy soil over loose gravel silt and clay material. Soil profiles tended to be 7.5YR/2.5/1. No hydrology was present. Shown is test pit #6. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Jensen Yorba Lott, Inc. Preliminary Jurisdictional Wetland Determination Report Page 9

13 Typical sample pit found along Bay Creek drainage. Sample plots were comprised of hydrophytic vegetation including grasses, horsetail, ferns, salmonberry, willow and alder. Soils were made of an organic silt loam (5YR/2.5/1) over 4 inches of gravel, silt and cobbles (5YR/3/3) and underlain with a gleyed clay profile (Gley 1/4/10G4). These soils had a high water table and saturation and were wetlands. Shown is test pit #7. Typical sample pit found in the saturated depression around the park shelter. Sample plots were comprised of hydrophytic vegetation with a histosol soil. Hydrology was present on the surface with drift marks, iron deposits over saturated soils. It is likely that the areas filled to accommodate the park shelter were comprised of these conditions prior to being disturbed and are likely below the 3 feet of fill material deposited. Shown is test pit #11. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 10

14 SUMMARY OF DELINEATION During the fieldwork, 13 sampling points were identified and catalogued. These are noted on Wetland Determination Data Forms-Alaska Region and can be found on the following pages. The inventory determined that a majority but not all intertidal areas tested positive for all three indicators of wetlands. Additionally an area is also found to be wetlands within the Bay Creek drainage. It is highly likely that a much larger area would have been within a wetland however the massive fill operations for the creation of the Horton Lot parking area has significantly altered the vegetation, soils and hydrology of the area. Of the total 2.44 acres inventoried, approximately 0.68 of an acre was determined to be wetlands. The wetland boundary and sample points are located on the site survey on the following page. This preliminary jurisdictional wetland determination indicates that there are less wetlands on site than indicated on the National Wetlands Inventory Maps. This is due to the modifications to the original landscape on the Horton Lot and adjacent park shelter. Following page: Topographic survey of project area with locations of test pits and wetland boundaries generated as part of this wetlands determination. Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 11

15 Portion of USS 3819 and 2664: Statter Harbor/Horton Lot Preliminary Jurisdictional Wetland Determination Report Jensen Yorba Lott, Inc. Page 12

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