FIGURE 2 Segments A-J of the Chittenden County Circumferential Highway.

Environmental Documentation

In seeking funding from the Federal Highway Administration (FHWA), the CCCH became a major federal action significantly affecting the quality of the human environment and thus must follow guidelines set forth in the National Environmental Policy Act (NEPA) of 1969. This is relevant because NEPA then directs that a detailed statement be prepared outlining:

1) the environmental impact of the proposed action; 2) any adverse environmental effects which cannot be avoided should the proposal be implemented; 3) alternatives to the proposed action; 4) the relationship between local short-term uses of man’s environment and the maintenance and enhancement of long-term productivity; and 5) any irreversible and irretrievable commitments of resources which would be involved in the proposed action should it be implemented (National Environmental Policy Act, 1969).

The Council on Environmental Quality (CEQ) is the authority responsible for implementing NEPA, requiring an EIS for any major project affecting the quality of the human environment. In this EIS all reasonable alternatives, including the proposed action and a “no action” alternative, must be considered. The impacts of each alternative are analyzed in great detail. From this, a “preferred” alternative is chosen.

CEQ regulations state that agencies must prepare supplements (SEIS) to draft or final EISs if 1) the agency makes substantial changes in the proposed action that are relevant to environmental concerns; or 2) there are significant new circumstances or information relevant to environmental concerns and with bearing up on the proposed action or its impacts (Council on Environmental Quality, 1978). The FHWA also has regulations that state that a SEIS is required when any new information or changes arise that were not initially evaluated in the EIS (Federal Highway Administration, 1988). If it is found that the proposed action is likely to have a significant impact on the environment, a new or supplemental EIS is required (Federal Highway Administration, 1988).

In 2002, a re-evaluation environmental assessment (REA) of Segments A-F was approved by the FHWA. This document identified the ecological impacts associated with building the new roadway (Table 1). The REA identified the following impacts: 25.1 acres of wetland, 115 acres of prime agricultural soils and no substantial impacts on local wildlife populations. These impacts to environmental resources are important in that they change the natural conditions. For instance, whether or not prime agricultural land is used for farming, impacts associated with building a new roadway can potentially

alter soil composition, chemistry, and structure. This study shall address these and other impacts. The Record of Decision (ROD) that was made in 2003 for Segments A-B concluded that there were no additional or significant environmental impacts and, thus, TABLE 1 Ecological Impacts Identified in 2003 Environmental Assessment

RESOURCE	2003 EA IDENTIFIED IMPACTS
Wetlands	25.1 acres of wetland impacts
Wildlife Habitat	No substantial impacts to local wildlife populations
Agricultural Lands	Approximately 115 acres of prime agricultural soils impacted
Streams/Water Bodies	Minimization and mitigation design features will be utilized to minimize impacts associated with the crossings

a new or supplemental EIS was not needed. Construction on these segments was ordered to begin in the summer of 2004. However, the District Court of Vermont found that the Vermont Agency of Transportation (VTrans) and the FHWA violated NEPA, CEQ, and FHWA regulations and stopped construction on Segments A-B of the CCCH on May 10, 2004 (Vt. District Court May 10, 2004). In order to resume construction, new documentation must be provided that includes a NEPA-compliant EA or SEIS that addresses new environmental concerns and documents cumulative and secondary impacts. Currently, VTrans and the FHWA are preparing a new EIS on transportation improvements along the Segments A-B corridor, taking a fresh look at all major issues and various options.

The intent of this current research is not to prepare the adequate environmental documents that are needed to resume construction on Segments A-B, but to further a new approach during the planning phases that is useful in determining the environmental impacts associated with building a new highway. The contribution to knowledge is applying a methodology that might prove useful in the preparation of the environmental documents needed for approval of transportation projects, thus avoiding costly delays.

METHODS

The methods used to address the objectives of this research vary depending on their application. In the first section, the analyses performed are primarily field-based, using built sections of the CCCH. Field observations and change detection analysis of the landscape are used to detect the road effects of Segments C-F on wetlands and water resources, roadside vegetation, and wildlife habitat and endangered species. In the second section, a GIS is used to address unbuilt portions of the CCCH. The road-effect zone methodology is applied to Segments A-B in order to determine the areas and resources that may potentially be impacted by road effects.

Field Analysis

To determine the number and location of all channelized or rerouted streams in the study site, all streams crossing built segments of the CCCH (C-F) were examined. The structure and condition of the waters crossing the roadway were then assessed in a more detailed change detection analysis of the landscape using aerial photographs from pre- and post-construction dates. Hard copy aerial photographs from 1988 were scanned and georeferenced to the 1999 digital images using a first order transformation. Images from both years were taken at the end of April. The precipitation patterns for Essex Junction, Vermont are comparable between 1988 and 1999. To address conditions upstream from the crossings, polygons of standing water were digitized to determine any drainage that may have occurred using digital images from both 1998 and 1999. During field verification, the locations of alterations that have occurred due to channelization were measured in order to determine downstream conditions. Such channelization modifications included bare muddy banks, muddy water, channel widening, channel degradation, and channel aggradation. Also for comparison, the most recent image of the study site, which was taken in 2004, was used to observe changes across three timeframes.

Allen Brook is a water body which could potentially be crossed by the proposed roadway (Segments A-B). This undisturbed water was compared with the affected water bodies crossing the built section of the roadway using the same methods that were used for Segments C-F. Aerial photographs from 1988 and 1999 were used to determine any disturbances that may have occurred between the two dates which are not related to road effects.

The number, location, and distance from the highway of all wetlands were determined using the Vermont Significant Wetlands Inventory (VSWI) data layer. Wetlands that intersected or were adjacent to Segments C-F were found by placing a one kilometer buffer around these segments of the CCCH. Those wetlands that contained altered streams were flagged for further examination. The same methods used to assess stream alterations were applied to determining any wetland drainage that may have occurred between 1988 and 1999 at water body crossings along built portions of the roadway. Wetlands located near unbuilt portions of the roadway were also assessed between 1988 and 1999.

In order to examine colonization by non-native (exotic) species along built segments (C-F) of the CCCH we employed a series of investigations. Exotic species were identified with the assistance of a VTrans grass and plant expert during a one-week period. First, the location of exotics in the roadbed was found and sketched onto a large-scale map while driving slowly in the shoulder of the road. Based on this map, return visits were made on foot using a Global Positioning System (GPS) to determine the exact locations and areas of exotics. The resulting database of non-natives present along built sections of the CCCH was compared with unbuilt areas (A-B) by again walking along the proposed alignment taking note of locations and areas of exotics with a GPS.

A multi-layer GIS analysis was used to determine the impacts of Segments C-F of the CCCH on wildlife. The primary wildlife species observed in the analyses were white-tailed deer and moose. Point locations of vehicular-related moose and deer mortalities as well as wildlife habitat layers were used to assess specific concentrations or species patterns. Vehicular-related moose and white-tailed deer mortalities have been recorded since January 2004 through a state-funded highway wildlife corridor project. A detailed data layer of white-tailed deer wintering areas has been developed by the Vermont Department of Fish and Wildlife (VFWD). These areas were mapped and field checked over a period of two decades. All of the data layers used in this analysis were created after the construction of Segments C-F, and are therefore representative of existing conditions (Table 2).

TABLE 2 Significant Ecological Data Layers

DATA LAYER	SOURCE	YEAR
Land Cover/Land Use	Vermont Center for Geographic Information	2003
Vermont Significant Wetlands Inventory	Vermont Agency of Natural Resources	1996
Agriculturally Important Soils	Natural Resources Conservation Service	2004
Endangered Species	Vermont Department of Fish and Wildlife	2003
Deer Wintering Areas	Vermont Agency of Natural Resources	1997

GIS Analysis

Segments A-B were chosen for this analysis because they are currently unbuilt and are the next segments scheduled for construction. Also, the environmental documents prepared for the segments are under examination because of their failure to meet NEPA, CEQ, and FHWA regulations. The first step in determining the road-effect zone for Segments A-B was to identify the core ecological areas and point locations in the study site (Table 2).

In this study, only those ecological impacts of transportation systems that extend the greatest distances are of interest (Forman and Deblinger, 2000). They include impacts on deer wintering areas, endangered species points, open grasslands, and regions with prime agricultural soils. Surface waters that are susceptible to road salt and runoff, wetlands, and water body crossings in the study site were also used. Impacts that only extend minimal distances, such as impacts to small mammal populations, are omitted from this study.

An overlay analysis of the study site was intended to identify natural areas that may be potentially impacted when the currently unbuilt segments (A-B) of the CCCH are completed. An initial buffer distance of one kilometer was used and placed around Segments A-B, with a total area of 16.17 km² (3,995.97 acres), in order to capture the environmental resources adjacent to the proposed alignment. This buffer distance was chosen based on previous studies that indicated road effects extending upwards of one kilometer from the road surface. All of these layers were clipped to the extent of the buffer in order to determine the exact area of resources potentially impacted. For the natural areas that intersected with the buffer but extended outside the layer, the polygon was not clipped. This process allows the entire area that may potentially be impacted by a road effect to be maintained. For example, it is believed that an entire wetland may be impacted if any of its area is being impacted by a road effect (Forman et al., 2003). A series of spatial joins were also completed to determine the distances of natural areas from the proposed alignment of the roadway.

Although all of the natural areas that were within the buffered area were identified in the overlay analysis, only those core areas vital to the delineation of the road-effect zone were retained (Figure 3). These areas are the principal ecological resources at risk of potential road effects that were used to delineate the road-effect zone.

FIGURE 3 Core areas of ecological resources used to delineate the road-effect zone.

In developing a probable road-effect zone for the area surrounding the proposed alignment of Segments A-B, the core ecological areas were manipulated in a GIS environment. Combining these areas with the most current orthophotographs allowed the exact borders for the zone to be determined. In the end, a road-effect zone polygon was digitized around the segments identifying the area that may potentially be impacted by road effects.

To further investigate, a series of GIS analyses were performed to determine the shape, size, and distance of the road-effect zone from the proposed alignment. It is important to understand the spatial nature of the zone to determine how different areas of the landscape interact with the proposed highway. To address this, buffers of 100 meter increments within the one kilometer buffer of the roadway were developed. This analysis divides the entire zone into sections based on varying distances from the roadway, creating characteristics unique to each section that can be further analyzed. These buffer layers were then intersected with the road-effect zone layer to determine the percentage of land within the zone at varying distances from the roadway. Finally the environmental variables used to delineate the zone were labeled to determine any patterns or relationships between various environmental resources at varying distances from the roadway.

RESULTS

The following is a summary of the results that were found in both the field and GIS analyses. Existing ecological impacts near Segments C-F of the CCCH are outlined in the first three sections. The final section summarizes results for the road-effect zone for Segments A-B. In both cases, the extent and magnitude of observed and predicted impacts greatly exceeded those identified in the REA prepared for the CCCH (Table 3).

TABLE 3 Comparison of Ecological Impacts

RESOURCE	2003 EA IDENTIFIED IMPACTS	ROAD-EFFECT ZONE IDENTIFIED IMPACTS
Wetlands	25.1 acres of wetland impacts	A-B: 41.06 acres C-F: 108.2 acres; 3280 m² of wetland drainage
Wildlife Habitat	No substantial impacts to local wildlife populations	A-B: 936.08 acres and two endangered species points C-F: 141 acres
Agricultural Lands	Approximately 115 acres of prime agricultural soils impacted	A-B: 720.93 acres (56.52 acres being farmed) C-F: 1,274.1 acres (58.07 acres being farmed)
Streams/Water Bodies	Minimization and mitigation design features will be utilized to minimize impacts associated with the crossings	A-B: Two water body crossings C-F: 200.04 meters of channelization

Wetlands and Water Resources

The Indian Brook is the only major water body crossing built portions of the roadway. It is channelized into a nine foot diameter culvert with stone channel bottom to flow under Segment F (Figure 4). A total 200.04 m of Indian Brook has been channelized and straightened due to the construction of this segment. Impacts from this alteration were noticeable both upstream and downstream from the road surface. There has been a dramatic loss between 1988 and 1999 of the standing water and wet areas that are located upstream from the crossing (Figure 5). The image used in Figure 5 was taken in 2004, 11 years after the opening of Segments C-F. The image indicates that conditions are beginning to slowly return to those that were present in 1988.

FIGURE 4 Steel culvert at Indian Brook crossing.

A total of 3280 m² (0.7953 acres) of standing water was lost between these two dates (Table 4). Also, indications of channelization, such as eroding banks and channel widening were noticed 100 meters downstream from the crossings. Results from the assessment of the undisturbed Allen Brook indicated no change in stream condition between the two time periods.

TABLE 4 Total Standing Water Upstream from Indian Brook Crossing (Square Meters)

1988	1999	% LOST
6644	3426	48.4

The results of the present study indicate that 22 wetlands intersect or are adjacent to Segments C-F. The total area of these wetlands is 43.79 hectares (108.2 acres). Indian Brook flows through four of the 22 wetlands, which are potentially drained due to alterations made by the water body crossing. The remaining eighteen are located adjacent to the roadway within the one kilometer buffer, leaving the possibility for wetland drainage to have occurred after the construction of the highway.

FIGURE 5 Spatial extent of standing water at the Indian Brook crossing in 1988 and 1999.

Three of the four wetlands that contain Indian Brook were chosen with the fourth being omitted due to inaccuracies in designating its boundary on the 1988 aerial photograph. All three wetlands experienced a decrease in area from 1988 to 1999 on the order of 1326.96-2715.85 m² (0.3279-0.6711 acres) (Table 5). These differences were compared with two wetlands located near the proposed alignment of Segments A-B. The undisturbed wetlands also experienced a decrease in area from 1988 to 1999 (Table 5). However, the percentage of change is much greater for those wetlands containing the altered Indian Brook.

TABLE 5 Change in Size of Wetlands Containing Indian Brook vs. Undisturbed Wetlands (Square Meters)

	ALTERED WETLAND 1	ALTERED WETLAND 2	ALTERED WETLAND 3	CONTROL WETLAND 1	CONTROL WETLAND 2
1988	8386	3542	13476	27447	16904
1999	5669	1372	12149	24814	15759
% Lost	32.4	61.3	9.8	9.59	6.77

Roadside Vegetation

The two non-native species that were found along the built segments were Purple loosestrife (Luthrum salicaria) and Common reed (Phragmites communis). These species are very common in North American freshwater wetland habitats and moist areas, much like that found in stormwater ditches and swales on roadsides. There were 19 point locations and 21 areas totaling 12,241.74 m² (3.025 acres) of non-native species along Segments C-F. There was no evidence of any colonization of non-natives into the natural communities surrounding the roadway. However, all of the stormwater detention and retention ponds were overrun by the Common reed plant. The plant covered between 50-80% of the total surface area, thus hindering the functionality of the ponds to filter stormwater runoff. In walking the area of the unbuilt portions of the roadway (A-B), there were no non-native plant species found. It is hypothesized that the stormwater system along Segments C-F is assisting in the transport of these species. The species tend to spread by short-distance movements, favored by ditches and culverts.

Wildlife Habitat and Endangered Species

In the built portion of the roadway (C-F) there have been two moose mortalities and one white-tailed deer mortality recorded to date. There is one white-tailed deer wintering area located in the study site, measuring 57.06 hectares (141 acres). This area intersects the roadway at Segment C and D and extends as far as 1.45 kilometers away from the roadway. Other wildlife information that was made available was not located within the study site and was therefore not used in this assessment.

Road-Effect Zone

The following are the results from the initial overlay analysis of the environmental resources located within the one kilometer buffer area of Segments A-B (Table 6). Nineteen wetlands, with a total area of 16.62 hectares (41.06 acres) intersected within the buffer area. The distance of wetlands from the roadway ranged from 0.109 km to 0.995 km. Seventy parcels contained prime agricultural soils with a total area of 291.75 hectares (720.93 acres). These areas ranged from 0 km to 0.997 km from the roadway. Of the agriculturally important soils, 10 parcels are currently being farmed, totaling 22.87 hectares (56.52 acres). The point locations of endangered species were analyzed based on their proximity to the roadway. There were two locations marked for endangered species in our study site, with one being only 111 meters from the proposed alignment. Four deer wintering areas are located in our study site. They totaled 378.82 hectares (936.08 acres) and ranged from 0 km to 0.663 km from the roadway.

TABLE 6 Summary of Ecological Impacts within 1km Buffer

ECOLOGICAL RESOURCE	NUMBER	AREA(HECTARES)	DISTANCE FROM ROAD (KM)
Wetlands	19	16.62	0.019-0.995
Prime Agricultural Soils	70	291.75	0-0.997
Actively Farmed Prime Soils	10	22.87	0.533-0.938
Endangered Species	2	0	0.11-0.997
Deer Wintering Areas	4	378.82	0-0.663

The road-effect zone for Segments A-B is displayed in Figure 6. The total area of the zone is 396.83 hectares (980.58 acres). The shape of the zone is asymmetric, varying in shape and size depending upon the environmental resources at risk on either side of the proposed roadway. The maximum distance that the zone extends outward from the proposed alignment is 885 meters. This occurs in an area where the roadway bisects a large tract of important wildlife habitat. The minimum distance of 24.65 meters occurs where there is development bordering the proposed roadway.

The results of the spatial analysis of the road-effect zone using buffers of 100 meter increments is summarized in Figure 7. The land area contained within the road-effect zone decreases with distance from the roadway. The buffer area with the highest percentage of road-effect zone is found within 100 meters of the roadway. The total area impacted within this zone is 133.64 hectares (330.23 acres). Approximately 33.68% of the total road-effect zone is located within 100 meters from the roadway while only 8.09% or 32.09 hectares (79.29 acres) is located greater than 500 meters from the road.

FIGURE 6 Road-effect zone for Segments A-B of the Chittenden County Circumferential Highway.

FIGURE 7 Spatial extent of impacted resources in the road-effect zone.

To conclude the analyses assessed, the ecological resources contained within the road-effect zone were further analyzed. Based on the size similarities of the potential water body crossings of Segments A-B with that of the Indian Brook crossing, we can estimate that these water bodies will be impacted approximately 300 meters upstream and 100 meters downstream from the point of crossing. These impacts are due to increased drainage (upstream) and erosion (downstream). Other impacts, such as downstream water quality or sediment deposition that may extend for greater distances were not assessed. Also, the effects of road salt on intermittent channels may extend outwards between 200-1500 meters (Forman and Deblinger, 2000). Open grassy areas, susceptible to noise and commonly host to a variety of birds and small mammals, ranged from 0-840 meters from the proposed roadway. While large tracts of agriculturally important soils were identified in the study area, most of them were not directly exposed to effects from the road. Many of the parcels were buffered by tracts of forest land. The same was true for wetlands identified in the initial overlay analysis.

DISCUSSION & CONCLUSION

The results from both the built and unbuilt portions of the CCCH (A-F) indicated that the magnitude and spatial extent of ecological resources impacted by the CCCH are much greater than were initially determined in the 1986 FEIS as well as the most recent 2003 EA/Reevaluation. The results of this study are compared with those impacts identified in the environmental documents prepared for the CCCH in Table 3. The current transportation planning process is one that makes it very difficult to incorporate issues of major importance into the implementation of transportation projects. The road-effect zone that was created in this study indicates the need to broaden the perspective that is used during the planning process in order to identify the environmental resources that are impacted by a road system.

Existing ecological impacts of the road on the surrounding land were seen by examining the built sections of the CCCH. To confirm that these alterations were directly linked to the road surface, unbuilt portions of the roadway were also analyzed through field observations and change detection of the landscape. During site visits, these unbuilt, undisturbed segments showed no impacts or change from a natural condition. This would support the results observed in the field for the built segments of the CCCH were directly related to road effects.

Numerous road effects impact water resources. Roads will inevitably cross or parallel streams and rivers as they meander over the landscape. Current practices are to minimize impacts associated with water crossings by mitigation efforts that strive to mimic natural conditions. However, these crossings can affect stream morphology in two major ways: by altering flow regimes and by scouring sediments and increasing sedimentation (Forman et al. 2003). As streams are placed into culverts to cross roadways, overall drainage densities increase, leading to increased flood velocity (Paul and Meyer, 2001; Hirsch et al., 1990) and wetland drainage (Forman and Deblinger, 2003). While measures are taken by state transportation agencies to minimize these impacts, the aquatic environment, wetlands, and surface water bodies are most commonly threatened.

VTrans has designed a culvert at the Indian Brook road crossing that strives to mimic natural conditions (Figure 4). Recent studies have shown that the design of active culverts is important to ecological connectivity (CDFG, 2002). For example, the California Department of Fish and Game (CDFG) have developed criteria to provide for upstream fish passage at culverts. Culverts, like those used by VTrans, are designed to intend to size a crossing sufficiently large and embedded deep enough to allow the natural movement of bedload and formation of a stable streambed inside the culvert (CDFG, 2002). However, at the Indian Brook crossing it was found that the total amount of channelization extended beyond 200 meters and impacts were noticed for a considerable distance both upstream and downstream from the roadway. Both direct and indirect impacts can be associated with this stream alteration. The drainage that has occurred upstream of the road crossing will decrease the amount of available aquatic habitat. There was also a significant loss of wetland density from drainage in the four wetlands that contained Indian Brook. Wetland drainage is often a result of road construction due to increasing flow downstream. The channel appears to have widened downstream from where the alterations occurred, thus causing an imbalance in the stream.

The ecological processes that shape a landscape can also be negatively impacted by roads. In this study, impacts from roads will also disturb the natural processes that maintain the condition of a stream. The same is true for other environmental resources analyzed in this study, including wildlife and soil characteristics. In the case of a large mammal, a road may intersect an important grazing area, reduce connectivity, or increase mortality due to the increase in mammals needing to cross a road to get to food. These examples indicate the impact that roads have on ecological processes.

Similar arguments that were made for water resources also apply to each ecological variable studied. In determining the environmental impacts of a new roadway, each variable should be assessed in the same manner as water resources were in the two previous paragraphs. In developing a road-effect zone for Segments A-B of the CCCH, a GIS was used to collect environmental data, perform spatial analyses, and predict potential environmental impacts. Six ecological variables were used, some of which extended nearly 0.9 kilometers away from the roadway. While the extent of the impact decreases with increasing distance away from the road, the total amount of ecological resources impacted is much greater than those identified in EAs and EISs needed to obtain the necessary permits to build a road.

A major limitation to this research is data availability of various environmental factors to the general public. These factors limit the conclusions that can be based on existing road effects, as well as those factors used to delineate the road-effect zone. Also, the impacts of environmental resources used to delineate the road-effect zone are approximated. The zone is drawn based on the presence of environmental resources and their potential for impact, as determined by field observations of the built segments and guided by studies documented in the literature. Impacts will vary depending upon the topography, weather, and many other site-specific variables. This zone represents an estimate of what can potentially be impacted and is a useful planning tool for identifying environmental impacts associated with developing a new roadway.

The extent and magnitude of the environmental impacts associated with a new roadway are often overlooked and underestimated in the planning process, but can be detrimental to ecosystem structure and function. Current trends of increasing population pressure and budding metropolitan areas result in transportation problems such as increased traffic congestion, wait times, pollution, and accidents. The response to many of these problems is the creation of new roads. The identification and understanding of the environmental impacts that these new roads will have on the surrounding land is vital to maintaining overall ecosystem health.

The analyses presented in this paper discuss the ecological factors that are being impacted or may potentially be impacted by road effects and offers a foundation for future transportation planning policy. The road-effect zone methodology provides an integrative approach for specific examples or for focusing on specific resources. This approach can also be useful in determining the least vulnerable route. As mentioned in the Environmental Documentation section, an EIS for a transportation project analyzes reasonable alternatives. The road-effect zone concept can be applied during this process to help identify which alternative will have the least overall impact on the environment.

Developing a new roadway while preserving natural resources is a challenging, yet obtainable goal. In the current EIS process for a new roadway, only the minimum environmental impacts are identified. It is recommended that the current transportation planning process broaden to include large-scale environmental impacts associated with building a new roadway.

ACKNOWLEDGEMENTS

The authors are deeply appreciative to members of the Vermont Agency of Transportation for their continued support throughout this project. The initial idea for this paper developed through the research of work completed by Dr. Richard T. T. Forman of the Design School at Harvard University. Finally, thanks goes to the individuals at the University of Vermont who made this all possible.

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INTRODUCTION

STUDY AREA AND CONTEXT

The Chittenden County Circumferential Highway