Summary
The construction and presence of the Lake Source Cooling (LSC) heat exchange facility (HEF) and terrestrial chilled water pipelines present potential short- and long-term impacts on terrestrial vegetation and wildlife within the project area. Selection of a pipeline route that runs through previously disturbed areas, such as existing rights-of-way and roadways, will preclude or minimize much of the potential ecological impact. Individual trees along the construction route were carefully evaluated to optimize the route location and protect as many trees as possible.
LSC researchers used literature surveys, interviews with local experts, and the collection of field data to determine the vegetation and community types present in the LSC project area. A separate inventory of maintained street trees was conducted in and along the construction rights-of-way. Fifteen vegetation associations were identified during field surveys in the project area. Three wildlife habitat types exist in the project area. Wildlife surveys conducted in the project area confirmed the presence of various common species of birds, mammals, amphibians, and reptiles. No state or federally listed threatened or endangered plant or animal species were found to occur on the HEF site, in the proposed staging areas, or within the limits of disturbance of the terrestrial pipelines. There are, however, several hackberry (Celtis occidentalis) trees in the project area that are listed as a unique feature in Tompkins County's Unique Natural Areas Inventory because the hackberry is at the northern extent of its range. The botanical significance of Renwick Slope and the physical characteristics of Fall Creek Gorge are the basis for listing these locations as Unique Natural Areas in Tompkins County. There are no wetlands in the project area.
Short-term impacts of the project on vegetation include the temporary disturbance of approximately 5.6 hectares (ha) (14 acres) of vegetated area at the HEF site and along the pipeline route during construction. This impact will be mitigated by the replanting of grass and shrubs, and by the replacement of disturbed street trees. Although some of the vegetation on Renwick Slope will be disturbed by construction of the HEF and the terrestrial pipelines, impacts to Fall Creek Gorge will be avoided. LSC construction may cause the temporary migration of wildlife from the area, but wildlife is expected to return to all disturbed areas except for the approximately 0.16 ha (0.4 acres) where the HEF and its paved parking area will be constructed.
Long-term impacts of LSC on terrestrial ecology include the permanent loss of approximately 1.63 ha (4.03 acres) of the existing wooded upland vegetation along the terrestrial pipeline route. Following construction, this corridor will be replanted and maintained as a grassed right-of-way and shrub area. The close proximity of similar undisturbed habitats reduces the impact of the woodland loss. The most significant long-term impact on vegetation and wildlife will be the permanent removal of approximately 0.16 ha (0.4 acres) of black locust/black cherry association for the construction of the HEF and paved parking area, which will be the only permanent vegetation loss. All other disturbed areas will be reseeded and allowed to revegetate naturally. Shrubs will be planted in selected locations. Three hackberry trees will be cleared from the project area, but these trees represent a fraction of the existing trees within the project area. A strong seed source will remain to perpetuate the hackberry in this area. Overall, impacts to the terrestrial ecology within the LSC project area are considered to be minor.
2.6.1 Environmental Setting.
The Lake Source Cooling (LSC) project area is located within what has been designated as the Allegheny Section of the Northern Appalachian Highland Division of the Hemlock-White Pine-Northern Hardwood Region (Braun 1950), and by the U.S. Forest Service as the White Pine-Hemlock-Hardwood Forest Section (Lull 1968). The Allegheny Section occupies most of the northern half of Pennsylvania and the southern half of New York.
Research of survey records provides a description of the character of the regional forest in the 1790s: "More than 97 percent of the landscape [of the Central Finger Lakes Region] was forested. Beech/maple/basswood was the predominant forest type throughout the region" (Marks, Gardescu, and Seischab 1992: 1). Based on this research, the oak forest was the primary forest type between Seneca and Cayuga Lakes. Disturbances due to wind, fire, beavers, and people were recorded on only 1 percent in the region.
Throughout most of the Finger Lakes area, the present vegetation bears little resemblance to the original cover. The forest vegetation of the upland areas was profoundly modified by lumbering and fire in the earlier periods, and by urbanization in more recent times. Remnants of the original forest cover remain in only a few places, preserved in regionally located state parks and wildlife preserves. These remnants indicate that the forest was a hemlock-hardwood woodland in which hemlock (Tsuga canadensis), American beech (Fagus grandifolia), and sugar maple (Acer saccharum) (in that order) were the most abundant in the canopy, while American beech far outnumbered other species in the subdominant layer and was well represented in all size classes (Braun 1950). Other prevalent species were black cherry (Prunus serotina), black birch (Betula lenta), yellow birch (Betula alleghaniensis), red maple (Acer rubrum) and white ash (Fraxinus americana). Tulip tree (Liriodendron tulipifera), cucumber magnolia (Magnolia acuminata), and basswood (Tilia americana) were also present. Herbaceous plants included spinulose wood fern (Dryopteris spinulosa), shining clubmoss (Lycopodium lucidulum), white wood sorrel (Oxalis montana), partridge berry (Mitchella repens), and Canada mayflower (Maianthemum canadense).
Presently, northward extensions of oak and oak-chestnut forests reach into New York State and are mainly established on gravelly soils in the valley head moraine belt south of the Finger Lakes. Diversity in topography and soils and the admixture of southern species give the Finger Lakes area more variety in forest types than is typical of the Hemlock-White Pine-Northern hardwoods region.
The project area is located at the interface between the northern hardwoods and the more southerly oak/yellow poplar tulip tree region (Lull 1968). As a result of local variation in microclimate, this area contains tree species common to both forest types. For example, though northern red oak is probably its most widely distributed harwood associate, other oaks, hickory, and occasionally even tulip tree are found in the southern part of this zone. In the northern or higher positions, other hardwoods typical of the beech-birch-maple region are common. Stand composition varies greatly with site and land-use history. On cool slopes, such as the heat exchange facility (HEF) site, particularly after the selective cutting of conifers, northern hardwoods prevail.
This section of the Draft Environmental Impact Statement (DEIS) focuses on evaluating the potential impact of LSC on terrestrial vegetation and wildlife in the project area. Direct impacts of the construction and operation of the LSC system will mainly be confined to areas within the limits of disturbance of the proposed terrestrial pipeline facilities, staging areas (materials/equipment), and the HEF site (including paved surfaces), collectively referred to as the project area. These impacts can be grouped into two categories: (1) impacts related to construction, many of which will be temporary; and (2) long-term impacts which are related to the operation of the HEF and maintenance of the pipeline rights-of-way.
The terrestrial pipeline route was selected with the intent of minimizing the overall environmental impact. The majority of the proposed pipeline route will be located either along the shoulders of existing roads or under the paved area of public roads. At different times, the terrain along the entire route has been previously altered or regraded. Consequently, the impacts to natural vegetation communities and wildlife will be minimized.
2.6.1.1 Vegetation Classification.
Based on the classification system used by the New York Heritage Program (NYSDEC 1990), the existing communities at the HEF site and along the proposed pipeline route primarily fall under the (IV) Terrestrial System, (C) Forested Uplands, and (20) Successional Southern Hardwoods categories. The (IV) Terrestrial System consists of upland habitats, with well-drained soils that are dry to mesic (never hydric), and vegetation cover that is never predominantly hydrophytic, even if the soil surface is occasionally or seasonally flooded or saturated. The (C) Forested Uplands include upland communities with more than 60 percent canopy cover of trees that occur on substrates with less than 50 percent rock outcropping or shallow soil over bedrock. The (20) Successional Southern Hardwoods consist of a hardwood or mixed forest that occurs on sites that have been cleared (e.g., for farming or logging) or otherwise disturbed.The dominant trees in the three referenced communities are usually any of the following: gray birch (Betula populifolia), hawthorns (Crataegus spp.), sassafras (Sassafras albidum), box elder (Acer negundo), American elm (Ulmus americana), slippery elm (Ulmus rubra), red maple, silver maple (Acer saccharinum), and eastern red cedar (Juniperus virginiana). Certain introduced species commonly found in successional forests have become naturalized, including black locust (Robinia pseudoacacia), tree of heaven (Ailanthus altissima), and buckthorn (Rhamnus cathartica). Any of these may be dominant or codominant in a successional hardwood forest, which is a broadly defined community dominated by light-requiring, wind-dispersing species that are well-adapted to establishment following disturbance.
A characteristic feature of successional forests is the lack of reproduction of the canopy species. Most of the tree seedlings and saplings in a successional forest are those of species that are more shade tolerant than the canopy species (e.g., sugar maple, American beech). Shrub layer and ground layer dominants may include many species characteristic of successional old fields, or they may include species that occurred on or near a site prior to disturbance. The Successional Southern Hardwoods community is found mostly in the southern half of New York, south of the Adirondacks. It is classified as G5 (demonstrably secure through its range) and S5 (demonstrably secure in New York State) (NYSDEC 1990).
A forest which has come in after some disturbance (e.g., logging, fire) is called a second-growth forest or secondary succession. The vegetation present on the HEF site is a second-growth successional forest dominated by black locusts.
The northern section of the pipeline right-of-way (along New York State Route 13) is more characteristic of second-growth shrubby areas, where numerous arboreal species are found. The area contains buried sanitary sewer lines, owned and maintained by the Town of Lansing and Village of Cayuga Heights, and an electric transmission line easement maintained by New York State Electric and Gas (NYSEG). Vegetation within the easement is grassed and periodically mowed to prevent establishment of herbaceous species.
2.6.1.2 Vegetation Survey.
To thoroughly assess existing conditions and potential impacts to vegetation that may result from the construction and operation of the project, the LSC research team conducted a literature survey, consulted local experts, and collected additional field data. The team consulted historic records and reports on the natural vegetation within the project area. The New York Natural Heritage Program provided information regarding known occurrences of rare or endangered plant species. Files and maps were reviewed, and interviews were conducted with the Tompkins County Planning Department (Skaley 1996). The team conducted a complete inventory of the trees planted and maintained by the Town of Ithaca and City of Ithaca along the proposed pipeline right-of-way, and recorded the information with site photographs (Appendix C-3). A lakefront assessment was completed to document the physical features of the Cayuga Lake shoreline and to identify any potential lacustrine wetlands or unusual lakefront vegetation in the project area.Several experts with particular interest or specialized knowledge of the project area participated in the field investigations of the proposed pipeline route. Nancy Ostman (from Cornell Plantations) and Robert Wesley (a local botanist who conducted a unique natural areas survey for Tompkins County) took part in the field investigation to identify the presence of any rare or endangered species or special habitats. Andrew Hillman, City of Ithaca Forester, examined street trees within the city limits and suggested mitigating measures. John Schroeder, a member of the Ithaca Environmental Council and a Cornell alumnus, provided information about trees on the Cornell campus that he had donated to the university. Additional landscape experts from the Cornell University staff consulted on the potential tree impacts along the campus portion of the proposed pipeline route.
2.6.1.2.1 Field Data Collection.
To characterize and classify the existing vegetation, the LSC research team used two methods of sampling vegetation. An intensive, quantitative sampling method was used in areas of potentially permanent impacts, such as the HEF site, while a more subjective sampling method was used in areas that would only experience temporary impacts due to construction, such as along the proposed pipeline route.The quantitative sampling effort was carried out in locations where the proposed project would result in the removal of large areas (greater than 1 acre) of vegetation. These areas included the HEF site and the adjacent soil disposal area south of Renwick Brook. A "tenth-hectare" quadrat sampling procedure was chosen for these areas since it provides quantitative information with relative efficiency. Using the tenth-hectare quadrat size (1,000 square meters [m2] = 0.1 hectares [ha] [0.25 acres]), researchers sampled vegetation to gather quantitative information on species representing a wide range of plant growth forms. The quadrat was comprised of a 20- x 50-m (65- x 165-feet [ft]) rectangular grid, with two 10- x 50-m (33- x 165-ft) strips, one to either side of the midline established by a 50-meter tape. The tape was held on the ground in a straight line, starting at a randomly selected point toward the lower portion of the quadrat, and extending directly up slope. Trees within the quadrat over 1.3 centimeters (cm) (1/2 inches [in]) diameter at breast height (dbh) were sampled, and the dbh for each species was recorded. Shrubs and saplings (tree stems less than 1.3 cm [0.51 in] dbh, but greater than 1 m [3.3 ft] tall) were counted. Herbs and seedlings were visually estimated by percent cover.
A more subjective, qualitative method (preferential sampling) was used in areas along the pipeline route and in proposed parking and staging areas (including Portland Point) that would experience only temporary impacts due to construction, and no permanent vegetation loss. Due to the irregular shapes of these areas and the discontinuous nature of the undeveloped land, preferential sampling was determined to be more appropriate than the quadrat method relative to study objectives and purposes. The major advantage of the preferential sampling approach is a substantial reduction in the required number of samples needed to characterize a given area. The major disadvantage is that data generated does not have the statistical significance of random sampling. In preferential sampling, the investigator selects sample sites that appear to be homogeneous and then distributes samples among the community types equitably. Once the initial homogeneous areas are identified, a centralized sampling system can be used. Using this system, LSC researchers examined areas within each community that appeared to represent the total segment, and then characterized them by percent cover of trees, shrubs, and herbaceous vegetation.
For the communities that were sampled quantitatively, several plant community measures were included in the data collected. The community measures can be used to develop association baseline conditions that can aid in evaluating project impacts and recommending strategies for mitigation. The community measures used included:
· Basal Area. Basal area is a common measure of ecological dominance. In woody plants, basal area refers to the cross sectional area at breast height and is expressed in square meters per hectare or square feet per acre. It is the area outline of a plant trunk near the ground surface. In trees, basal area is measured through the dbh. In shrubs, the basal area of a species is measured at ground level, and stems over 1 cm diameter (.39 in.) are counted. The herbaceous layer was not included in the basal area estimates.· Abundance of Each Species. Evaluated as the number of individuals per unit area (density) or subjective cover assessment.
2.6.1.3 Project Area Vegetation Associations.
Fifteen plant species associations were found along or near the proposed terrestrial pipeline route, 12 of which are forest communities. Two non-vegetated associations were also classified. The associations are listed below for each section of the pipeline corridor. The abbreviations following the association names correspond to those used on the maps shown in Figures 2.6-1, 2.6-2, and 2.6-3, which depict the 15 definable plant associations that presently exist within the project area. The two non-forest associations along the pipeline route are categorized as urban/disturbed and residential.
VEGETATION ASSOCIATIONS:
HEF SITE, SOIL DISPOSAL AREA, AND CHILLED WATER TRANSMISSION PIPELINE ROUTE*Forest Associations
Black Locust/Black Cherry (BL/BC)
White Oak/Chestnut Oak (WO/CO)
Renwick Brook/Streamside (RB)
Eastern Red Cedar/Herbaceous (ERC/H)
Tartarian Honeysuckle/Shrub (TH/S)
Staghorn Sumac/Shrub (SS/S)
Norway Maple (NM) Stand
Eastern Cottonwood (EC)
Black Walnut/Black Locust (BW/BL)
Hackberry/Black Locust (H/BL)
Japanese Knotweed/Tartarian Honeysuckle (JK/TH )
Black Locust/Tree of Heaven (BL/TofH)
Nonforest Areas
Urban/Disturbed
Residential
Planted/Maintained Trees (MT) (various individual species)
Maintained Grass Right-of-Way
Goldenrod/Open (G/O)*Shown in Figures 2.6-1, 2.6-2, and 2.6-3.
Designated associations represent areas of definably similar physical characteristics, as expressed by the observable groupings of a certain population of species. The important factors used to delineate plant associations within the project area included the following:· Life Form. This factor considers the height, growth form, and structural characteristics of the dominant species (i.e., tree, shrub, vine, herb, fern, ground cover, and whether the species is herbaceous or woody).
· Degree of Disturbance. The degree and length of time since the last disturbance, as determined by indicators of disturbance.
· Species Composition. This factor considers the relative importance of certain assemblages of species and species groupings with the community. Dominant species are used to define the associations.
The plant species associations listed in the following sections are in the order of their general locations along the project area, starting north at the HEF and proceeding south. All of the communities within the project area were previously disturbed and are in various successional stages (see Figures 2.6-4, 2.6-5, and 2.6-6). Some are early successional associations, such as eastern red cedar/herbaceous (Juniperus virginiana), staghorn sumac/shrub (Rhus typhina), Tartarian honeysuckle/shrub (Lonicera tatarica), and Japanese knotweed/Tartarian honeysuckle. The other associations are more mature and are classified as second-growth forest. The mature associations include black locust/black cherry, white oak/chestnut oak, Norway maple (Acer platanoides), eastern cottonwood (Populus deltoides), black walnut/black locust, and hackberry/black locust. Some associations are related to specialized habitats, such as the Renwick Brook/ streamside association.
The vegetation characteristics were also surveyed at two equipment/material staging areas along the proposed pipeline route. The planned temporary parking area north of the HEF site has been recently disturbed and is presently in an "old field" succession dominated by an eastern red cedar/herbaceous association. Portland Point will be used for the temporary storage and assembly of the marine and chilled water pipelines. The site is presently an industrial area and includes a residence. A former industrial building is located at the Portland Point site. The structure is dilapidated and is in the process of being removed. The site will be used primarily for pipe storage and assembly, and is planned for development by the current owner. Presently, the central portion of the site that will be used for storage is devoid of vegetation. Along the lake edge, there are scattered remnants of eastern cottonwoods, ranging from 3 inches to 37 inches dbh, and black willows (Salix nigra) ranging from 2 inches to 31 inches dbh. There are scattered groups of shrubs dominated by staghorn sumac and Tartarian honeysuckle. The herbaceous area is sparse and dominated by goldenrod (solidago spp.), jimson weed (Datura stramonium), cocklebur (Xanthium strumarium), and evening primrose (Oenothera biennis).
The location and extent of the communities within the project area are shown on Figures 2.6-1, 2.6-2, and 2.6-3. The extent of each community is tabulated in Table 2.6-1. Each association is described in subsections 2.6.1.3.1 through 2.6.1.3.17.
2.6.1.3.1 Black Locust/Black Cherry Association (BL/BC).
The black locust/black cherry mixed hardwood association appears to be an upland second-growth forest, and is a direct result of some significant site disturbance (e.g., selective clear cutting). The association is found at several different locations along the proposed pipeline route and at the proposed HEF site (Figure 2.6-1). Cumulatively, the association consists of approximately 1.63 ha (4.03 acres). It is generally established on western-facing, moderately steep slopes (15 to 20 percent). The canopy closure of the overstory is about 75 percent, with a moderate to dense understory and sparse ground cover.The dominant association species are black locust (60 percent of the total basal area), black cherry (Prunus serotina) (21 percent), black walnut (Juglans nigra) (16 percent), eastern red cedar (2 percent), and box elder (1 percent). The dominant seedlings are white ash. Dominant shrubs include Tartarian honeysuckle (30 percent), black raspberry [blackcap] (Rubus occidentalis) (10 percent) and red raspberry (Rubus idaeus) (5 percent). Vines include Japanese honeysuckle (Lonicera japonica), poison ivy, and Virginia creeper (Parthenocissus quinquefolia). Other trees outside of, but near the sampling plot, include hackberry (Celtis occidentalis), red oak (Quercus rubra), sycamore (Platanus occidentalis), shagbark hickory (Carya ovata), river birch (Betula nigra), choke cherry (Prunus virginiana), sassafras, staghorn sumac, and winged sumac (Rhus copallina). Other herbaceous species include depford pink (Dianthus armeria), motherwort (Leonarus cardiaca), and roughfruited cinquefoil (Potentila recta).
2.6.1.3.2 White Oak/Chestnut Oak Association (WO/CO).
This association is found along the southern edge of the HEF site and on the thin soils above Renwick Brook (Figure 2.6-1). Total association area is about 0.07 ha (0.18 acres). It is comprised of an open oak woods area dominated by 15- to 46-cm (6- to 18-in.) dbh white oaks (Quercus alba) and smaller chestnut oaks (Quercus prinus), red oaks, and basswood. Buckthorn is the dominant shrub with a sparse understory layer dominated by switchgrass (Panicum virgatum) and Kentucky bluegrass (Poa pratensis), mixed with scattered herbaceous plants such as intermediate bush clover (Lespedeza intermedia).2.6.1.3.3 Renwick Brook/Streamside Association (RB).
This linear-shaped association lines the northern and southern sides of Renwick Brook (Figure 2.6-1). The vegetation consists of mixed deciduous trees and shrubs and a sparse herbaceous layer. Although the association is protected by the steep slopes on both sides of the brook, the vegetation has been significantly disturbed as a result of the construction associated with the abandoned rail line, NYS Route 34 (East Shore Drive) and the Village of Cayuga Heights sewer line (to the east), and the culvert under NYS Route 13. The association is comprised of scattered trees dominated by white ash, box elder, and staghorn sumac. There is a relatively diverse and dense shrub layer with nannyberry (Viburnum lentago), red osier dogwood (Cornus stolonifera), and multiflora rose (Rosa multiflora). The shrub area is approximately 0.02 ha (0.04 acres) and is located between East Shore Drive and NYS Route 13. The microclimate of the brook is moist and protected.2.6.1.3.4 Eastern Red Cedar/Herbaceous Association (ERC/H).
The red cedar/herbaceous association is an old field community in the early stages of succession. It occupies about 1.2 ha (2.94 acres) of land along most of the sloping New York State Department of Transportation (NYSDOT) right-of-way adjacent to NYS Route 13 (Figure 2.6-1). The canopy layer covers about 10 percent of the area, with the dominant vegetation being grasses and scattered shrubs. There are no large trees in the association. Scattered small eastern red cedars dominate the shrub/understory layer. The dominant understory vegetation is pioneer and exotic species, including box elder, staghorn sumac, cherry (Prunus spp.), and Japanese honeysuckle. The herbaceous layer is dominated by grass species that may have been seeded by the NYSDOT for bank stabilization.2.6.1.3.5 Tartarian Honeysuckle Shrub Association (TH/S).
South of Renwick Brook, east of East Shore Drive and west of the Village of Cayuga Heights sewer line, is a moderately steep (15 to 20 percent) west facing slope that supports a very dense Tartarian honeysuckle shrub association (Figure 2.6-1). It is an early successional shrub-dominated association, with scattered individual trees that comprise the very open canopy, a dense understory shrub layer, and a very sparse herbaceous layer. The previous disturbance in this area appears to be the result of selective or clear cutting and past development, as indicated by old building foundations. Many of the dominant species in this association are non-native species. Total association area is approximately 0.41 ha (1.01 acres).The dominant association species are Tartarian honeysuckle, which covers about 85 percent of the area (although only approximately 4 percent of the total basal area), and staghorn sumac (16 percent of the basal area). Overstory trees are scattered and dominated by black walnut, which makes up 26 percent of the total basal area. Red cedar is also prevalent (18 percent of the basal area), as well as black cherry (11 percent). White ash, box elder, sycamore, eastern cottonwood and sweet cherry (Prunus avium) make up the remaining basal area. Vines include Japanese honeysuckle, poison ivy, and Virginia creeper. Due to the areal extent of the Tartarian honeysuckle, there is very little herbaceous cover in the association. A few scattered herbaceous species include American speedwell (Veronica americana) and daisy fleabane (Erigeron annuus).
There are also some scattered black cherry, black walnut, white ash, eastern cottonwood, and sycamore trees. Herbaceous plants include switchgrass. The dominant vine is summer grape (Vitus aestivalis).
2.6.1.3.6 Norway Maple Association (NM).
North of the Village of Cayuga Heights Wastewater Treatment Plant (CHWWTP) is a 0.03-ha (0.07-acre) grove of Norway maples with a sparse understory and herbaceous layer (Figure 2.6-1). It appears to be a remnant maple stand that became naturalized from planted Norway maples in surrounding previously disturbed areas. There is another 0.06-ha (0.16-acre) stand located near a residential area along the southern portion of the proposed pipeline route (Figure 2.6-2).2.6.1.3.7 Staghorn Sumac/Shrub Association (SS/S).
The staghorn sumac shrub association is an early successional forest with an open canopy, a moderate to dense understory, and open ground cover. It is typically located on previously disturbed areas along the proposed pipeline route and south of the CHWWTP (Figure 2.6-1). Dominant overstory vegetation is staghorn sumac, with an inclusion of scattered black locusts and trees of heaven. The understory shrubs consist of red osier dogwood and silky dogwood (Cornus amomum). Herbaceous plants include switchgrass, intermediate bush-clover (Lespedeza violacea), Roman wormwood (Artemisia pontica), and Canadian goldenrod. Cumulatively, the association is approximately 0.22 ha (0.55 acres) in size.2.6.1.3.8 Eastern Cottonwood Association (EC).
South of Renwick Brook and east of the Cayuga Heights sewer line is a western facing slope that supports an eastern cottonwood mixed hardwood forest association (Figure 2.6-1). There is a similar association south of the CHWWTP. Cumulatively, the association has a total area of approximately 0.71 ha (1.76 acres). The canopy is dominated by eastern cottonwood (28 percent), black walnut (23 percent), and pin oaks (Quercus palustris) (21 percent), which together provide nearly 100 percent canopy closure. Other species in the canopy layer include red oak, bur oak (Quercus macrocarpa), white oak, and white ash. Just below the canopy are some smaller trees, such as black cherry, sweet cherry, red cedar, and buckthorn. There is a sparse to moderate understory composed mostly of gray dogwood (Cornus racemosa), Tartarian honeysuckle, and fly honeysuckle (Lonicera canadensis), and a sparse ground cover layer with field garlic (Allium vineale), box elder seedlings, and grass species.The eastern cottonwood association between Renwick Brook and the Cayuga Heights sewer line is relatively mature and has a high species diversity. The second area, south of the CHWWTP, is less diverse. Although it is dominated by eastern cottonwood, the second area also contains Eastern hop hornbeam (Ostrya virginiana) in the overstory, and Tartarian honeysuckle and silky dogwood in the shrub layer.
2.6.1.3.9 Goldenrod/Open Association (GR/O).
This early successional community, located north of the John C. Lowery Construction Company site, is a very open association, dominated by a variety of herbaceous plants, such as goldenrod species (Figure 2.6-1). The 0.11-ha (0.28-acre) area, called "ruderal," is degraded in that it is on fill material and/or severely disturbed soil rather than native soil. The plants in this association are early pioneer species. Many of the plants could be considered "weed" species, including tall goldenrod (Solidago altissima), goldenrod (S. arguta), ragweed (Ambrosia artemisiifolia), foxtail grass (Setaria sp.) and Japanese honeysuckle.2.6.1.3.10 Black Walnut/Black Locust Association (BW/BL).
The black walnut/black locust association is a 0.07-ha (0.17-acre) mixed hardwood forest community. This second growth forest association, like the other plant communities within the project area, results from recent site disturbance. This association is located south of the CHWWTP in a few scattered areas (Figure 2.6-1).The dominant association species are black walnut, black locust, black cherry, and box elder. The dominant shrubs include Tartarian honeysuckle and black raspberry. Vines include Japanese honeysuckle and poison ivy. Herbaceous species include panic grass (Panicum latifolium), hairy wild rye (Elymus villosus), and Meadow onion (Allium canadense).
2.6.1.3.11 Hackberry/Black Locust Association (H/BL).
The hackberry/black locust association is comprised of second growth mixed hardwoods. Although this association is found at a few different locations along the pipeline route, the main area occurs along a raised ridge adjacent to and just west of NYS Route 13 near the intersection with East Shore Drive (Figure 2.6-1). Cumulatively, the association is approximately 0.10 ha (0.25 acres) in size.The dominant association species are hackberry, black locust, butternut (Juglans cinerea), black cherry, swamp white oak (Quercus bicolor) box elder, and maple. The dominant shrubs include Tartarian honeysuckle and black raspberry. Vines include Japanese honeysuckle and poison ivy. Herbaceous species include common mugwort (Artemisia vulgaris), clasp-leaf Venus' looking glass (Triodanis perfoliata), Virginia sickseed (Hackelia virginiana), and panic grass.
2.6.1.3.12 Japanese Knotweed/Tartarian Honeysuckle Association (JK/TH).
There are a number of small, previously disturbed areas dominated by Japanese knotweed and Tartarian honeysuckle in this association. The association contains a few black walnut trees, box elders, and some scattered buckthorn, and is generally found in poorly drained areas that have been recently disturbed. The association primarily occurs in an area west of NYS Route 13, north of the East Shore Drive intersection (Figure 2.6-1). The total association area is approximately 0.02 ha (0.05 acres).2.6.1.3.13 Black Locust/Tree of Heaven Association (BL/T of H).
The black locust/tree of heaven association is comprised of second growth, mixed hardwoods resulting from recent site disturbance. This 0.07-ha (0.17-acre) association occupies the Gun Hill slope on the eastern side of Lake Street and west of the former Ithaca Gun factory (Figure 2.6-2). It is dominated by non-native trees, such as Tree of heaven and Norway maple. Another codominant is black locust, a pioneer species that often invades disturbed sites. Other species include American plum, box elder, northern catalpa (Catalpa bignonoides), black walnut, basswood, slippery elm, and staghorn sumac. There is also a sparse understory.2.6.1.3.14 Maintained Grassland Right-of-Way (MG).
Along the rights-of-way for the existing Town of Lansing and Village of Cayuga Heights sewer lines, there is a mixed grassland association that is maintained through periodic mowing (Figures 2.6-10 through 2.6-11). The grasses are mixed, and include wide-leaved panicum (Panicum latifolia), Kentucky bluegrass, red fescue (Festuca rubra), and Canada brome (Bomus purgans). Other herbaceous species include round-head bushclover (Lespeza capitata) and crownvetch (Coronilla varia), that have probably moved in from the adjacent NYSDOT right-of-way. Vines in the association include poison ivy and Japanese honeysuckle. The cumulative area of this association is approximately 0.97 ha (2.4 acres).2.6.1.3.15 Planted/Maintained Trees (MT).
Most of the pipeline route is either adjacent to or within road rights-of-way. The impact of LSC in these areas is on individual trees that have been planted and, in some cases, maintained by the City of Ithaca or the property owners. For these areas, indicated on Figures 2.6-1, 2.6-2, and 2.6-3 as MT, an individual tree inventory was undertaken.The inventory of individual trees on the road right-of-way or on school property was conducted along the proposed pipeline route south of the NYS Route 13 overpass. Any tree that was within the limits of disturbance of the pipeline (defined by the tree crown or dripline) was included in the survey. Many of the trees are maintained by the Ithaca City School District. Other trees are maintained by individual property owners (e.g., Cornell University). There were 118 trees delineated within the proposed construction limits of the preferred pipeline route. Trees included in the inventory were selected based on their location, type, physical condition, and/or size. Additional shrubs, scrub trees, etc., are located within the construction right-of-way, but were not inventoried. The non-inventoried trees will be removed during construction as necessary, but will be protected and saved whenever possible. Figures 2.6-14 through 2.6-23 show the locations of each tree inventoried, and also indicate which ones will be removed or protected during construction. Approximately 25 different species were identified during the inventory between the HEF and campus. Except for the hackberry, the species are all either planted street trees or are trees that have established themselves from seed or other reproductive means. The trees range in diameter from 15.2 to 101.6 cm (6 to 40 in.). The species include black locust, white ash, hackberry, butternut, American basswood, silver maple, eastern cottonwood, box elder, apple species, American sycamore (Platanus occidentalis), northern red oak, flowering dogwood (Cornus florida), white mulberry (Morus alba), and sugar maple. Table 2.6-2 is a complete list of all trees inventoried.
Appendix C-3, a Photographic Atlas of Significant Vegetative Assemblages, provides the tree-specific data and includes a photograph of each surveyed tree. The appendix also contains a general description of each tree by a series of specific characteristics.
2.6.1.3.16 Urban/Disturbed (UD).
Areas that are dominated by impervious cover and which lack vegetation have been classified as urban/disturbed. This category includes areas such as the CHWWTP, which have little or no vegetation (Figure 2.6-1). Approximately 9.6 ha (23.75 acres) within the project area have been categorized as urban/disturbed.2.6.1.3.17 Residential (R).
The residential associations include a mixture of maintained trees, shrubs, and grasses (lawns), often with remnant trees and shrubs that were not cleared for the original development (Figures 2.6-1 and 2.6-2). Cumulatively, these areas account for approximately 0.1 (0.25 acres).2.6.1.3.18 Unique Natural Areas.
The Tompkins County Unique Areas Program lists unique areas and rare or endangered species of concern within the county. The HEF site and part of the proposed pipeline right-of-way are located within the Renwick Slope unique natural area (designated IT-29 on the Tompkins County Unique Natural Areas Inventory). The designation is based on the botanical significance and the presence of rare plants reported on the site. The area is generally located along the east shore of Cayuga Lake, and is indicated in Figure 2.6-1. Six vegetation species are reported to be within the Renwick Slope area, including slender forked chickweed (Paroncychia canadensis), moss pink (Phlox subulata), hoary mountain mint (Pycnanthemum incanum), early blue violet (Viola palmata), heart-leaved Alexanders (Zizia aptera), and hackberry. Hackberry is the only reported species that was found to occur within the limits of disturbance of the Lake Source Cooling project.The hackberry is listed as unique for Tompkins County because the area is the northern extent of the species' range, which extends from Massachusetts to Idaho and south to northern Florida, Tennessee, Arkansas, and Oklahoma. The tree can grow to heights of 28 m (91 ft), and is found in woods, river banks, rocky barrens, and on dry to moist sandy soils. The hackberry is noted for its interesting bark characteristics. Since it typically is a southern species, the hackberry is found only in sheltered locations within the Ithaca area. Small, scattered populations can be found in Coy Glen, Ithaca Falls, Stewart Park, and on gravelly areas at the base of cliffs and bluffs along Cayuga Lake. The population along the pipeline may have originated from the Stewart Park population (Ostman and Wesley 1996). The hackberry association is located east of East Shore Drive, adjacent to a residential area north of the NYS Route 13 overpass (Figure 2.6-1).
Another unique natural area (IT-11 on the Tompkins County Unique Natural Areas Inventory) near the proposed pipeline route is at the base of Ithaca Falls on Fall Creek, approximately 213.4 m (700 ft) east of the Lake Street bridge.
2.6.1.3.19 Threatened or Endangered Species.
The Natural Heritage Program of New York State was contacted to ascertain whether any threatened or endangered species or critical habitats have been recorded within the project area. A number of species are listed within the Ithaca East and Ithaca West United States Geological Survey (USGS) topographic quadrangles. Listed species include butterwort (Pinguicula vulgaris), bird's eye primrose (Primula mistassinica), Kentucky coffee tree (Gymnocladus dioica), swamp loosewort (Pedicularis lanceolata), woodland bluegrass (Poa sylvestris), swamp smartweed (Polygonum setaceum var. interjectum), purple meadow-parsnip (Thaspium trifoliatum var. flavum), tawny emperor (Asteerocampa clyton), yellow giant hyssop (Agastache nepetoides), downy lettuce (Lactuca hirsuta), and rockcress (Draba arabisans). None of the species are federally listed as threatened or endangered. The listed species were not found within the limits of disturbance of the HEF, the proposed pipeline route, or piping laydown areas (e.g., Portland Point) during site surveys.2.6.1.4 Wetlands.
There are no wetlands at the HEF site or along the proposed pipeline route. Stream crossings are explained in Section 2.4, Tributaries. There is only one area adjacent to the proposed pipeline route that contains hydric (wet) soils, but the area has been disturbed and is not covered by a dominance of hydrophytic vegetation that typically thrive in hydric soils. The area of hydric soils is not a wetland according to either the New York State Department of Environmental Conservation (NYSDEC) or the United States Army Corps of Engineers (USACOE) criteria. The hydric soil area is within the boundary mapped as the Japanese knotweed/Tartarian honeysuckle area (Figure 2.6-1). This small area is dominated by Japanese knotweed and Tartarian honeysuckle, both of which are introduced species. These plants are also characterized as facultative upland species (FACU), which means that they generally do not occur in wetlands. The area also contains, but is not dominated by, black walnut trees and box elders (FACU species) and some scattered common buckthorn, which is an upland species.2.6.1.5 Wildlife.
Four general categories of wildlife habitat types exist in and around the project area. The habitat types are Cayuga Lake, lakeshore areas, urban/residential areas, and undeveloped areas (see Figures 2.6-7, 2.6-8, and 2.6-9).Wildlife use of the project areas has been determined from a combination of existing documentation and on-site field surveys. Detailed field surveys were conducted throughout the entire project area with a primary focus on the HEF site. Field work was completed on April 11 and June 4, 1996. Further observations were made on Cayuga Lake during water sampling and Mysis relicta study events. The wildlife surveys were conducted in the spring and early summer so that the presence of transient migratory and nesting migratory bird species could be confirmed.
2.6.1.5.1 Cayuga Lake Habitat.
Cayuga Lake is an important habitat for both local and migratory wildlife. Its location within the eastern flyway makes it an important stopover and/or overwintering habitat for migrating water birds. The lake's wintering waterfowl populations are among the highest in New York State due to its position in the flyway, food resources, surrounding agricultural fields, and the relatively low level of disturbance in nearby roosting areas.2.6.1.5.2 Lakeshore Habitat.
Construction of the lakeshore will be limited to installation of the lake water pipelines and a concrete anchor vault at 1000 East Shore Drive (marina site). The lakeshore in this area is primarily a narrow, gravelly strip developed with seasonal cottages, mowed lawns, and includes a few large trees. In the project area, the shoreline is valuable to riparian wildlife, such as wading birds, amphibians, and water-oriented mammals. The habitat value has been degraded by human disturbance and development in the vicinity of the project area.2.6.1.5.3 Urban/Residential Habitat.
Urban/residential areas provide habitat features for wildlife species that are tolerant of human activity. The majority of the project-related construction will take place in and along paved roads and road rights-of-way with adjacent areas that have wildlife habitat value. Street trees, lawns, open areas, and the Cornell University campus comprise the naturalistic habitat areas. Buildings and other structures primarily provide bird habitat for nesting and roosting.2.6.1.5.4 Undeveloped Habitat.
Undeveloped land within the project area includes the HEF property at 983 East Shore Drive, the narrow strip of land between East Shore Drive and NYS Route 13 located south of the HEF site, and an area to the south of CHWWTP (Figure 2.6-7). These areas are characterized by second-growth deciduous woods, scrub/shrub growth, and open linear corridors. The second-growth deciduous woods are limited in terms of acreage, but are contiguous to a long corridor of similar habitat to the north. The result is a continuous corridor of habitat that serves as a travel lane for wildlife, providing connections to other habitats, including urban areas and nearby Stewart Park. The second-growth deciduous woods are fringed by associated scrub/shrub growth and are bisected by an electric transmission line right-of-way maintained by NYSEG. This bisection of the deciduous woods creates an open linear corridor. The resultant edge ecotone is one of the primary habitat features of the project area.The construction of NYS Route 13 to the east of the site has created a gravelly, steep slope with shallow soil and few nutrients, and is excessively drained. Therefore, ecological succession in the area is slow. The slope is primarily vegetated with upland grasses and a few shrubs. Although the majority of this old field habitat occurs off site, on the eastern slope along East Shore Drive, it influences species composition within the nearby project area.
Gorges have formed in places within the project area where tributaries have eroded undeveloped steep sites. Two such gorges are notable in the proposed project area: Fall Creek Gorge and Renwick Brook. The shaded gorges have a moist microclimate that is favorable to many salamander species. A talus layer at the bottom of the cliffs also provides cover and foraging areas for these species. The cliff faces provide perching, nesting, and feeding habitat for birds. Some small mammals may also use these areas for foraging or cover.
2.6.1.5.5 Wildlife Surveys.
Wildlife species in the project area were confirmed by sightings, calls, tracks, scats, nests, burrows, feathers, and feeding signs. A list of wildlife species thought to use the project area was compiled from a review of published literature pertaining to known ranges and habitat requirements of individual species (see Table 2.6-3). A species was included on the list if suitable habitat was present in the project area. Species were also included if it is likely that they use the project area as a travel corridor or as part of their home range.The Wildlife Resources Center of the NYSDEC was asked to review the Natural Heritage Program files for biological information concerning records of sightings for rare, threatened, or endangered species. The only wildlife concern listed for the project area was the importance of Cayuga Lake as a waterfowl concentration area. A similar request was made to the U.S. Fish and Wildlife Service (USFWS), New York field office in Cortland. No records of federally listed endangered or threatened species exist for the project area.
No threatened or endangered wildlife species were found at the HEF site or along the proposed pipeline route during on-site surveys. Species identified on Cayuga Lake, however, included the common loon (Gavia immer), which is listed as a species of special concern in New York, and the common tern (Stearna hirunda), which is listed as a threatened species in New York.
Each individual species listed in Table 2.6-3 has a habitat requirement that is met by one or more of the four generalized habitat categories identified in the beginning of this section. Few species listed use project area habitats as a complete home range, since the HEF site is small and the proposed pipeline route is narrow. Most species utilize the project area for only a portion of their habitat needs.
2.6.2 Impacts of the Proposed Action.
2.6.2.1 Short-Term (Construction).
2.6.2.1.1 Vegetation.
Direct, short-term impacts of LSC on terrestrial ecology will result from construction of the terrestrial pipeline sections, the proposed HEF site, the expansion of paved surfaces and parking lots, and the use of staging areas. The extent of the impacts will vary in different areas, depending on the type of disturbance and the specific vegetation associations impacted (see Table 2.6-1). Early successional communities (e.g., old field) will take less time to return to their predevelopment conditions than a mature community. Indirect impacts of construction runoff on vegetation downslope from the site will be minimized by the implementation of approved stormwater management and erosion control measures (Appendix C-16).The limits of disturbance of the proposed terrestrial pipeline route, the HEF and its paved areas, and the staging areas will impact approximately 5.6 ha (14 acres) of plant communities (see Table 2.6-1). Figures 2.6-10 to 2.6-23 show the limits of disturbance and are arranged in sequence from the HEF site southerly to the Cornell campus. The areas listed on these figures correspond to those listed in Section 1.4.2. With the exception of 0.16 ha (0.4 acres) covered by the HEF and associated paved parking area, the removed natural vegetation associations (as opposed to planted trees) will be reseeded and restored to allow successional shrub associations and/or grasses to re-establish. The overall impact will therefore be temporary or involve a change from the existing communities to a shrub/herbaceous or grassed association. In areas where the existing vegetation is mature, this represents a greater ecological change than if the vegetation has been recently disturbed. In other areas, the impact of construction on the terrestrial environment is not considered significant because most of the plant communities to be impacted are already disturbed and contain a high number of non-native species. The only location with mature vegetation is a small area adjacent to the proposed HEF site (see Figure 2-6.4).
Three hackberry trees will be removed during construction (Figure 2.6-15). The removal of the three common hackberries does not constitute a significant impact to the scattered, yet prevalent populations of hackberries in the Ithaca area. As long as significant seed sources remain to continue the propagation of hackberries, the overall impact will not be significant. Many hackberries will remain throughout the pipeline route, including a large stand just north of the HEF site (see photographs of Tree Nos. 12, 13, and 14 in Appendix C-3).
The impacts on individual trees along Lake Street, University Avenue, and on the Cornell campus are indicated in Figures 2.6-14 through 2.6-23. Trees that require removal are indicated in the figures by dark shading; trees that can be saved, but require protection, are indicated with a bold outline. Table 2.6-2 lists all trees inventoried and indicates whether removal or protection is anticipated.
Individual trees along the construction route were carefully evaluated to optimize the route location and save as many trees as possible (see Section 2.6.3 for discussion of mitigating measures for tree preservation methods). For example, on the upper portion of Cornell's "Library Slope," which has significant trees, the chosen pipeline route follows the existing paved pedestrian walkway so that only three trees will be impacted. The trees to be impacted are generally in poor health and do not include significant species. In the lower section of "Library Slope," the proposed pipeline route saves a sweet pignut hickory (Carya glabra) and removes a yellow buckeye (Aesculus octandra) tree. There are two other yellow buckeyes on campus, and the sweet pignut hickory is a longer lived tree that has a tap root (which makes the tree difficult to transplant) and is an exceptional specimen at old age. The yellow buckeye can be replaced with nursery stock if desired.
There will be minimal disturbance of vegetation at Portland Point.
There are no significant parcels of terrestrial vegetation associations at the HEF site or along the proposed pipeline right-of-way. Construction activities at the HEF site, the staging areas, and along the pipeline route will result in the temporary disturbance of approximately 5.6 ha (14 acres) of vegetation (Table 2.6-1). With the exception of 0.16 ha (0.4 acres) at the developed HEF site, the temporarily disturbed areas will be stabilized, restored, and revegetated; thus, the impacts of construction are not considered to be significant. See Section 2.6.2.2 for a discussion of permanent impacts.2.6.2.1.2 Wetlands.
There are no wetlands on the HEF site or along the proposed pipeline right-of-way and therefore there will be no associated impacts.2.6.2.1.3 Wildlife.
Temporary impacts to wildlife will result from construction activities. Initial impacts to the project area during construction will include clearing of vegetation and regrading of soil.Along the pipeline route, most of the impacts to wildlife will be temporary, since the majority of the disturbed habitats will be restored to pre-existing conditions. Some large trees will be permanently removed, but most trees will be protected along the edge of the pipeline route, minimizing impacts to wildlife. The majority of construction will occur in existing paved roadways, and therefore will have no measurable effect on wildlife habitat. Noise and other disturbances caused by construction crews may cause wildlife to move away from the construction area. The wildlife species will return to the area, however, soon after construction is over.
Since the habitat areas found at the HEF site are connected to other similar and larger habitats to the north, many species will temporarily relocate in these nearby areas during construction. The limits of construction of the project were chosen in part to avoid impacts to gorges and wetland areas. Therefore, potential impacts to the amphibians, small mammals, and riparian birds that use these habitats will be eliminated.
The Cayuga Lake and shoreline habitat areas may be temporarily impacted during construction. Temporary local disturbances to wildlife may occur at the shore during construction, but wildlife will return to these areas soon after construction ceases. Although two species (common tern [Sterno hirundo] and common loon [Gauia immer]) that are listed as threatened and of special concern by NYSDEC were observed on Cayuga Lake during site visits, these species are water birds and will easily avoid the construction activities. Therefore, the proposed project will have no permanent impact on these species.
The design of the LSC facilities and the selection of the pipeline route have minimized effects on wildlife. Wherever possible, impacts to existing wildlife habitats have been avoided. No significant change in species diversity or density is expected to result from the construction and operation of the proposed LSC project.
2.6.2.2 Long-Term (Operations).
2.6.2.2.1 Vegetation.
Portions of the existing plant communities will be permanently altered by the proposed project. The main long-term impact is the removal of the existing plant association at the HEF site for construction of the building and its associated paved parking lot. The development of buildings, roads, and grading will remove approximately 1.63 ha (4.03 acres) of the second-growth black locust/black cherry association at the HEF site. All but the 0.16 ha (0.4 acres) permanently cleared for the HEF building and associated paved parking area will be revegetated. The remainder of the cleared area at the HEF site will be revegetated with grass and shrubs as part of the HEF landscape plan. Therefore, a permanent net loss of only 0.16 ha (0.4 acres) of vegetation will result from HEF site construction. This impact is not considered significant because of the previously disturbed nature of the existing plant association.There will be some minor impact on forested sections of the proposed LSC project area, such as the HEF site. The pipeline right-of-way will be maintained occasionally to prevent establishment of tree species. Most forested areas will be largely undisturbed by the LSC project.
Approximately one-half of the 118 inventoried street trees will be removed during construction. With the exception of three hackberry trees along the route on the Boynton Middle School property, the trees are all relatively ordinary species, and therefore the impact is not considered significant. Although the hackberry is designated as scarce in upstate New York (and is therefore considered a unique resource), it is found in a number of sheltered locations in the Ithaca area. The removal of several hackberries is not significant, as long as enough hackberries remain in the project area as a seed source. Individual trees are less important seed sources than mature stands. A large stand of hackberries north of the HEF site will be undisturbed, and a number of individual trees will remain along the pipeline right-of-way, providing a large seed source for the area. The number of hackberry trees impacted by the project is a small fraction of the total number in the area.
There will be no significant impacts to parcels of terrestrial vegetation at the HEF site or along the proposed pipeline right-of-way. Impacts to vegetation will be mitigated by revegetation and replanting efforts, as described in Appendix C-16.
2.6.2.2.2 Wildlife.
Permanent impacts on wildlife will result from the construction of the HEF and related parking areas. The HEF site building, parking lot, and lawn will replace existing habitats. Impacts of these actions were the primary focus of the wildlife survey, since they will have a permanent effect on site habitats. Some small mammals will be able to adjust to the new habitat types, and other mammal and bird species that are better adapted to human disturbance will inhabit the landscaped areas of the constructed HEF building. Species that already exist in the urban/residential areas may expand their range to include the area of the newly constructed HEF site. Most of the habitat along the pipeline route will not be permanently impacted by construction and will maintain the property's function as a travel corridor for wildlife. The construction of the HEF and paved parking will result in the permanent loss of about 0.16 ha (0.4 acres) of wooded wildlife habitat, and therefore does not represent a significant wildlife impact. No significant permanent impacts on wildlife will result once the pipelines have been installed.2.6.3 Mitigating Measures.
2.6.3.1 Minimize Disturbance of Vegetation.
Most of the impact on vegetation associated with the project are related to the clearing and removal of vegetation during construction. Project construction will be staged so that each disturbed area along the pipeline route will be stabilized and restored prior to beginning construction in a new area. Such a sequence will reduce areas of disturbance and allow for rapid stabilization and revegetation. The areas along the pipeline will be backfilled with clean fill to restore the original soil profile (top soil on the top layer). For the first 2,000 feet of the pipeline from the HEF, there will be some filling and regrading required. Past this section, to the extent possible, the final grade will be the same as the original.2.6.3.1.1 Revegetation.
Although approximately 5.6 ha (14 acres) of existing vegetation will be removed during construction, the permanent loss of vegetation will only be 0.16 ha (0.4 acres) attributed to the HEF and paved parking area. The remaining disturbed areas will be revegetated with grasses and shrubs and, in most cases, be allowed to succeed naturally. All vegetated area cleared during construction, except for approximately 1.5 acres of the permanent 15-foot right-of-way (including existing and new maintained grass areas) and 1.3 acres of the developed HEF site (including building, parking lot, and lawn) will be reseeded and allowed to revegetate naturally. Shrubs will be planted in selected locations.The right-of-way will be seeded with grasses. Native species of grasses and herbs will be used, such as Kentucky bluegrass, annual bluegrass (Poa annua), and red fescue. Other grasses may include little bluestem (Schizachyrium scoparius), big bluestem (Andropogon gerardii), Indian grass (Sorghastrum nutans), and Virginia wild-rye (Elymus virginicus) for dry soils. These grasses will be supplemented with a variety of forbs (Table 2.6-4 and Appendix C-16) to add to the habitat value of the proposed pipeline right-of-way. The grass species (marked G on Table 2.6-4) will make up about 50 percent of the seed mix, and the forbs (marked F and FC on Table 2.6-4) will comprise the other 50 percent. Those marked G should make up 50 percent of the mix, while those marked F and FC should comprise 35 percent and 15 percent, respectively. The forbs marked FC are to add color and interest to the mixture. The species selected are ones that thrive in a corridor situation and will not invade adjacent forested areas.
Shrubs will be planted to add habitat value along the construction right-of-way. Areas disturbed during construction beyond the permanent right-of-way will be planted with the grass mixture, as well as shrubs. Native shrubs include gray dogwood and red osier dogwood (see Appendix C-16.)
The inventoried street trees can be replaced at some cost. In some cases, replacing a large tree with a number of smaller trees would be practical and has been recommended by the City of Ithaca Forester. Street trees that need to be removed will be replaced with equivalent caliber trees. For example, if a 30.5-cm (12-in.) dbh tree is removed, it will be replaced with either two 15.25-cm (6-in.) dbh trees or three 10.2-cm (4-in.) dbh trees. The replaced tree species will be taken from the recommended tree list provided by the City of Ithaca. The replaced tree species and their locations will be selected in consultation with the Ithaca City School District, the City Forester, adjacent landowners, campus landscape experts, and approval groups. In some cases, the replacement tree(s) could be more desirable species than those removed. A tree (species) will not be replaced without the permission of the involved landowner(s).
2.6.3.1.2 Tree Protection.
Trees not removed along the construction right-of-way can be affected by project construction in a number of ways. First, construction equipment can cause surficial wounds and tears to the bark and branches. Second, there can be impacts to the foliage (burns) resulting from exhaust from equipment parked under the tree canopy. Finally, roots can be impacted to varying degrees through soil compaction, augering, and trenching of pipelines. The majority of these impacts can be mitigated using the appropriate precautions.During construction projects, existing trees often need to be protected from physical injury and root zone compaction caused by heavy equipment. One protective measure is to erect a barrier enclosing an area as large as the root zone of the plant or plants to be preserved. The barrier prevents compaction of soil and other forms of damage to the existing roots, and also prevents vehicles from driving over or into the plant. Figures 2.6-24 and 2.6-25 illustrate options for protecting trees during construction. The following discussion suggests additional mitigating measures that may be applicable in selected cases.
2.6.3.1.2.1 Trunk Protection.
Trunk damage in the form of bark tears rarely kills a tree outright, but it can serve as an entry point for decay organisms, which in time cause the tree to die. Surficial wounds can be mitigated by a number of tree protection measures such as those specified above (Figures 2.6-24 and 2.6-25). Final trunk protection measures will be incorporated into the LSC construction specifications.Tree wrap should be applied to all trees that require protection and which will be saved. In addition, according to the Cornell standards of construction, temporary fencing should be placed if possible along the drip edge of the protected trees to keep vehicles a sufficient distance so as to avoid any contact and injury. Figures 2.6-24 and 2.6-25 illustrate typical trunk protection measures. If damage does occur during construction, impacted bark will be trimmed, shaped neatly, and painted with a tree-wound dressing.
2.6.3.1.2.2 Foliage Protection.
Exhaust fumes from vehicles or construction equipment that may be parked under tree canopies for an extended length of time can burn the foliage and seriously damage (or kill) a tree. Most of the larger construction equipment will move along with the pipe installation operation which will generally proceed at a rate of 25 to 50 feet per day, so their exhausts should not impact the vegetation. All construction vehicles will be properly tuned and all exhausts will be suitably muffled. In addition, the construction barrier(s) mentioned above will be used to generally ensure that other vehicles cannot park under tree canopies with the engines running. A field manager will ensure that vehicles do not park under tree canopies.2.6.3.1.2.3 Root System Protection.
The basic function of plant roots is to provide anchorage, food storage, and absorption and conduction of water and nutrients. The overall vigor of a tree depends on the root system, which is influenced by soil, moisture, and climate conditions of the site. Root systems have distinct parts which are shown in Figure 2.6-26.The primary area of potential tree impact associated with pipeline construction is the root system. Root damage can occur from the surface as a result of soil compaction by construction vehicles, and can result from the subsurface excavation of the pipeline trench.
Construction work that must occur in close proximity to the root systems of valuable shade trees shall be conducted with the following general factors in mind. The criteria described below will be considered in determinations of where to hand trench, machine trench, or install shoring.· The size of root systems varies with species, soil, water, temperature and obstructions in the substrate. Classifying root characteristics of different species is difficult, since the systems are highly variable. In general, there are three types of root systems: (1) tap root systems (e.g., sweet pignut hickory, white oak); (2) lateral root systems that consist of large, shallow, flat roots that spread below the surface (e.g., sugar maple, silver maples, American beech, poplars); and (3) intermediate root systems, which have wide-spreading and deep lateral roots (e.g., Norway maple, northern red oak, and little leaf linden). For most trees, the largest number of roots is usually found within the uppermost 50 cm (19.6-in.) of the soil. The majority of the smaller fibrous absorbing roots generally grow in the upper 15 cm (6-in.) soil layer. Some roots, however, reach far greater depths. Almost without exception, lateral roots typically encountered in trenching are not found at ground depths below 18 to 24 inches.
· Trenching should be done outside the rapid taper zone (the root area closest to the trunk where impacts would be most severe) (see Figure 2.6-26). For mature trees, the rapid taper zone generally extends 4 to 6 feet out from the stump. In young trees, the rapid taper zone is scaled down proportionately. Beyond the rapid taper zone, tree roots generally decrease in diameter to 3/4 inch and less.
· The density of spacing or competition among individual trees has a pronounced effect on the extent of lateral root development, making generalizations about the extent of lateral development difficult. For trees growing in open areas, it is common to find lateral roots extending outward two or three times beyond the radius of the crown, although the majority of the absorbing roots may lie within the area circumscribed by the periphery of the crown.
· The preferred trenching distance from a tree is generally beyond the drip line.
· It is difficult to determine from the ground level the extent of root system development on the side of the tree that the pipeline trench will pass. There are indicators, however, that can be used to help predict the root system extent. Root systems will generally concentrate on the richest, least rocky, and most moist soils. For example, for most species, if there is a ditch carrying water near a tree, the most dense root growth will be toward the ditch.· Any roots 2 inches or larger that are damaged or cut during construction should be sawed off close to the tree side of the trench.
· The trench should be backfilled as soon as possible to keep roots from drying out.
· The greatest stress on a root system occurs during the leafing-out period, which is during the spring. During the leafing-out period, tree roots are most sensitive to impacts because: (1) the tree's demand for moisture is at a peak; and (2) root regeneration and replacement is very slow or nonexistent. Construction crews should take extra precautions during this period to reduce root damage (i.e., backfilling as soon as possible, keeping exposed roots wet, and saturating soil when backfilling around roots).
· The sandier the soil, the greater the root area.
· The heavier the foliage top, the more extensive the root system.
· Tree root systems under natural conditions undergo constant change. Main lateral roots die and new ones develop from the root crown throughout the life of the tree.
· In cases where trees are damaged by construction, they should be fertilized according to standard tree maintenance practices.
· In cases where roots are cut back as a result of construction, proper pruning standards should be applied to compensate for root loss, while still maintaining the natural character of the tree.
2.6.3.1.2.4 Post-Construction Monitoring.
Trees will be monitored after construction is complete to assure that restoration, erosion control, and reseeding efforts are successful. Trees with roots that have been affected shall be monitored by an environmental specialist. If, within one year after construction, the tree exhibits signs of deterioration that may be attributed to damage incurred during construction, a determination shall be made to either remove or care for the tree.2.6.3.2 Maintenance Practices on the Pipeline Right-of-Way.
On most rights-of-way, it is desirable to prevent the growth of trees and other woody vegetation with roots that could potentially damage the underground chilled water lines, and which could become obstacles to routine maintenance activities, such as checking pipeline cathodic protection points. Mowing on a twice-per-year cycle and/or brush-hogging on a three- to five-year cycle are considered the best ways to maintain a grass and wildflower cover. Such practices promote a healthy native diversity of local plant life.2.6.3.3 Minimize Disturbance of Wetlands.
Since there are no wetlands within the project area, associated mitigative measures are not necessary.2.6.3.4 Minimize Disturbance of Wildlife.
The short-term impacts to wildlife will be minimized by the rapid restoration and subsequent revegetation of native plant species, as outlined in Appendix C-16. The long-term impacts resulting from the construction of the HEF will be mitigated by replanting of native species with high wildlife value as part of the site landscaping plan.2.6.4 Unavoidable Impacts.
The unavoidable impacts to the terrestrial ecology of the project area will be the permanent loss of 0.16 ha (0.4 acres) of vegetation within the black locust/black cherry community, which is being replaced by the HEF and associated paved parking area.
