CUMULATIVE 

CHAPTER 5 
5.0 Cumulative 

The vertical line in the margin identifies text that has been modified in this Final EIS and

differs from the corresponding text in the Draft EIS 

5.1 Cumulative Impacts 

NEPA requires federal agencies to consider the cumulative impacts of proposals under their review. 

Cumulative impacts are defined in the CEQ regulations 40 CFR 1508.7 as “...the impact on the environment 

that results from the incremental impact of the action when added to other past, present, and reasonably 

foreseeable actions regardless of what agency... or person undertakes such other actions.” These actions 

include current and projected area development (e.g., oil and gas); management activities and authorizations 

on public lands (e.g., range conversion and forestry programs); land use trends; and applicable 

industrial/infrastructure components (e.g., utility corridors). Although the individual impacts of each separate 

project might not be significant, the additive effects of multiple projects could be. 

The primary cumulative impact study area consists of an existing utility corridor that the Overland Pass 

pipeline would traverse throughout its length. The widest portion of this corridor (approximately 2 miles wide) 

extends from Granger, Wyoming (RP 30) to the Wyoming/Colorado border (RP 330). Up to eight existing 

natural gas, refined products, and NGL pipelines occupy this corridor. Other linear facilities located within or 

adjacent to this large pipeline corridor include I-80, the Union Pacific Transcontinental Railroad, several fiber 

optic cables, and low voltage electrical transmission lines. Also included in this cumulative study area are 

pipeline projects approved or under construction (Rockies Express/Entrega and Enterprise Western 

Expansion). Nearby communities in Wyoming served by I-80 include Wamsutter, Rawlins, Laramie, and 

Cheyenne. Oil and gas well field developments are located within this major east-west utility corridor in the 

Great Divide Basin (vicinity of Wamsutter). 

The reasonably foreseeable pipeline projects are those currently being reviewed under NEPA (Overthrust 

Wamsutter Pipeline Project, Pinedale Anticline Pipeline Supplemental Environmental Impact Statement 

[SEIS], Kanda Lateral), and oil and gas field and mining development applications and Environmental 

Assessments (EAs) submitted to the BLM. On June 21, 2007, Overland Pass submitted an SF-299 for the 

Piceance Lateral project. This lateral pipeline would connect a 150-mile, 14-inch-diameter NGL pipeline from 

the Piceance Basin in northwest Colorado to the Echo Springs meter and pump station. 

Projects and activities included in this analysis generally are those located within the same counties directly 

affected by construction of the Overland Pass Project. Most effects of more distant projects are not assessed 

because their impact generally would be localized and would not significantly contribute to cumulative impact 

in the proposed project area. However, the air quality study area consists of the regional air sheds. Table 5.1-1 

identifies existing, under construction, or proposed projects that were evaluated in the Overland Pass Project 

cumulative analysis. 

Figure 5.1-1 is a schematic drawing illustrating the number of existing gas and liquids pipelines included in the 

existing utility corridor where the Overland Pass would be located, as well as sensitive resources encountered 

along the entire route. The majority of the existing pipelines in this utility corridor were constructed in the last 

30 years, and the revegetation of the ROW has varied with climate and soil type. From Rawlins eastward, 

grasslands largely have recovered to former cover; the scrub-shrublands consisting of saltbush and Wyoming 

sagebrush from Rawlins, Wyoming, west to Opal, Wyoming, have only partially recovered former shrub cover 

and height. Recent or proposed pipeline projects, such as the Overthrust Wamsutter Expansion Pipeline, and 

Enterprise Western Expansion, would be only partially revegetated by the time Overland Pass proposes to 

construct its pipeline. 

5.1-1
For this analysis, cumulative impacts were based on existing (through 2006) and foreseeable project surface 

disturbances that occur within 1 mile of the proposed Overland Pass pipeline route. Table 5.1-2 provides an 

estimate of the utility use surface area for the projects considered in this analysis. It is estimated that the total 

cumulative utility surface use area for this project exceeds 200 square miles over the 759.9-mile Proposed 

Action length. The Overland Pass pipeline would contribute approximately 5 percent of this total, and other 

new pipeline projects from 1 to 2 percent. Surface disturbance widths of 75 feet were assumed for the small 

diameter pipeline projects (Overland Pass, Enterprise Western Expansion), and 125 feet for the large diameter 

Rockies Express/Entrega pipeline. Older existing pipelines and the I-80 corridor which have largely 

revegetated ROWs are discussed within cumulative impacts as appropriate (e.g., habitat fragmentation). 

Table 5.1-1 Projects with Potential Cumulative Impacts on Resources within the General Area of the 

Proposed Overland Pass Pipeline 

Project /Activity 

Project 

Location 

(State) 

Counties Where 

Project Coincides 

with the Proposed 

Overland Pass 

Pipeline Description 

Anticipated Date of 

Construction/ Project 

Status 

Multiple existing 

natural gas, NGLs, 

and petroleum 

products pipelines; 

fiber optic cables; 

ancillary 

aboveground 

facilities (compressor 

and pump stations). 

Wyoming, 

Colorado, 

Kansas 

All counties crossed 

by the project. 

In Wyoming, multiple pipelines (up to 8) are located 

in a wide utility corridor that extends from RP 27 to 

RP 330. The Overland Pass pipeline is not located 

in this utility corridor between RP 54 and RP 103, 

and from RP 137 to RP 163. From RP 330, the 

Overland Pass pipeline parallels the Southern Star 

natural gas pipeline for the majority of the length to 

the terminus at RP 749. 

Existing, constructed 

prior to 2006 

Rockies Express/ 

Entrega Project. 

Wyoming, 

Colorado 

Wyoming: 

Sweetwater, Carbon, 

Albany, Laramie; 

Colorado: Weld 

328 miles of 42-inch-diameter natural gas pipeline. 

The Overland Pass pipeline parallels the Rockies 

Express/Entrega Pipeline for 164 miles from RP 166 

east of Wamsutter to the Colorado/Wyoming border 

(RP 330). The project includes a new compressor 

station at Wamsutter, Wyoming. The Echo Springs 

lateral that feeds the Entrega Pipeline near 

Continental Divide would cross over the Overland 

Pass pipeline north of I-80. 

Construction underway; 

in-service by 2008 

Enterprise Western 

Expansion Project 

Wyoming Sweetwater 50,000 bpd expansion of existing NGL pipeline 

system, consisting of 202 miles of looped pipeline 

segments and pump station upgrades. Three loop 

segments would be located adjacent to the 

Overland Pass pipeline ROW. Total length parallel 

to Overland Pass pipeline is approximately 20 miles. 

ROD issued in 2005; 

under construction 

Overthrust 

Wamsutter Pipeline 

(evaluated as part of 

the Rockies Express/ 

Entrega Project). 

Wyoming Sweetwater 77 miles of 36-inch-diameter natural gas pipeline 

between Green River (Kanda) and Wamsutter, 

includes 2 compressor stations. This project (among 

others) would convey gas to the Rockies 

Express/Entrega Pipeline at Wamsutter. 

Final EIS issued March 

2007; under construction 

El Paso Kanda 

Lateral Project 

Utah, 

Wyoming 

Sweetwater 128 miles of 30-inch natural gas pipeline between 

the Uinta Basin, Utah, and Kanda, Wyoming. The 

Kanda Lateral would cross over the Overland Pass 

pipeline at the Kanda hub (RP 63). 

EA issued March 2007; 

under construction 

5.1-2
Table 5.1-1 Projects with Potential Cumulative Impacts on Resources within the General Area of the 

Proposed Overland Pass Pipeline 

Project /Activity 

Project 

Location 

(State) 

Counties Where 

Project Coincides 

with the Proposed 

Overland Pass 

Pipeline Description 

Anticipated Date of 

Construction/ Project 

Status 

Questar Rendevous 

Pipeline Project 

Wyoming Sweetwater Approximately 103 miles of 30-inch pipeline from 

the Pinedale Anticline to the vicinity of Granger, 

Wyoming. This pipeline would cross over the 

Overland Pass pipeline at RP 28. 

Included in the Pinedale 

Anticline Supplemental 

EIS being prepared by 

the Pinedale BLM office; 

Draft EIS released 

January 2007 

Piceance Basin 

Pipeline Project

1 

Colorado, 

Wyoming 

Carbon An approximately 150-mile, 14-inch NGL pipeline 

from the Piceance Basin in Colorado to Echo 

Springs, Wyoming. The pipeline would have a 

projected capacity of 100,000 bpd. As currently 

planned, the pipeline would use the existing 

Overland Pass pipeline Echo Springs pump station 

at the northern end of the line. This station is 

located on private land and is electric powered. As 

such, no additional long-term air emissions are 

expected. Based on preliminary information, the 

Piceance Basin lateral would have minimal 

geographic overlap with the Overland Pass pipeline 

ROW where the two pipelines intersect at the Echo 

Springs Pump Station near RP 146.5. 

Begin construction in 

summer of 2008 

Oil and Gas 

Development 

Wyoming Sweetwater Vermillion Basin Area; up to 56 gas wells southwest 

of Bitter Creek. 

Drilling in progress 

Sweetwater Pappy Draw Exploratory Coal Bed Methane (CBM) 

Project; drill 20 exploratory wells in BLM’s Pappy 

Draw Unit Area. 

BLM EA in progress 

Carbon Atlantic Rim Natural Gas Development Project; drill 

2,200 wells over 20 years in southern Carbon 

County. 

FONSI/DR issued May 

2007 

Carbon Seminoe Road Gas Development Project; drill and 

operate 1,240 CBM wells over a 30- to 40-year 

project life; includes 16-inch diameter gas 

transmission pipeline. 

BLM Final EIS in 

progress 

Sweetwater Continental Divide – Creston Project: drill and 

develop 8,950 natural gas wells approximately 

40 miles southwest of Rawlins, Wyoming. 

BLM NOI published 

March 2006 

Sweetwater, Uinta, 

and Lincoln 

Moxa Arch Area Infill Gas Development Project: infill 

drill 1,860 natural gas wells. 

BLM Draft EIS in 

progress 

Carbon Brown Cow II POD: drill and develop 12 coal bed 

natural gas (CBNG) wells in Atlantic Rim Natural 

Gas Development project area, approximately 

7.5 miles north of Baggs. 

FONSI/DR issued 

September 2006 

Sweetwater Hiawatha Field Project: drill up to 4,207 natural gas 

wells. 

NOI issued in 

September 2006 

Mining Wyoming Sweetwater Pit 14 (Coal) Lease: addition of maintenance tract 

adjacent to the existing Black Butte Mine. 

Final EIS issued 

November 2006 

1

The information to date is based on the project proponent’s application for ROW filed with the BLM on June 21, 2007 and a March 2007 

press release issued by ONEOK Partners, L.P. Based on this preliminary information, the construction of the Overland Pass pipeline 

would be completed before construction is initiated on the Piceance Basin Pipeline. 

5.1-3 
Table 5.1-2 Estimated Cumulative Utility Use Area within the Existing Utility Corridor Occupied by the Proposed Overl

Overland 

Pass RP 

Begin 

Overland 

Pass RP 

End Miles 

Existing 

Pipelines 

(Estimated) 

Existing1 

Estimated 

Corridor Width 

(feet) 

Existing 

Utility Use 

Surface Area 

(square mile) 

Overthrust 

Wamsutter Pipeline 

Surface Area 

(square mile) 

Overland Pass3 

Utility Use Surface 

Area (square mile) 

Ente

Util

Surfa

(squa

0 9 9 0 to 2 100 0.2 0.1 9 27 18 3 300 1.5 0.3 

27 44 17 6 600 5.0 0.2 44 50 6 6 300 2.8 0.1 50 54 4 2 150 1.5 0.1 54 62 8 1 75 0.9 0.1 62 68 6 0 0 0.0 0.1 0.1 68 76 8 1 75 1.1 0.1 76 103 27 0 0 0.0 0.4 

103 120 17 3 500 11.4 0.2 120 137 17 0 500 13.0 0.2 137 148 11 1 75 2.1 0.2 148 159 11 0 0 0.0 0.2 159 163 4 1 75 2.3 0.1 163 196 33 5 600 22.3 0.7 0.5 196 236 40 6 to 8 500 22.3 0.9 0.6 236 269 33 6 to 8 700 35.7 0.8 0.5 269 294 25 6 400 22.3 0.6 0.4 294 307 13 6 500 29.1 0.3 0.2 307 323 16 4 300 18.4 0.4 0.2 323 336 13 3 300 19.1 0.2 336 749 413 1 75 10.6 5.9 

Total 749 221.5 3.8 10.6 1The existing utility corridor includes pipelines, pump and compressor stations, fiber optic lines, Interstate Highways, and railroads. The overall corridor width is the s

utilities within approximately 1 mile of the proposed Overland Pass pipeline centerline. Secondary roads and highways are not included in this estimate. 

2Overthrust Wamsutter Pipeline. The utility use area is based on a surface disturbance width of 125 feet. 3Overland Pass, Enterprise Western Expansion Pipelines. The utility use surface area for each project is based on a surface disturbance width of 75 feet. 

5.1-4
Raptor Breeding Areas 

Wildlife 

Resources 

Areas 

I-80 Corridor 

Oil and Gas 

Developments 

6 to 8 

Arlington 

Arrowhead 

C

olora

do 

W

yoming

C

olora

d

o

K

ansas 

Opal Meter 

Station RP 0.0 

Echo Springs Pump 

Sage Grouse Habitat 

Overthrust Wamsutter Pipeline 

Enterprise Western Expansion 

Laramie Keota/Raymer Bird City Bushton Conway 

Big Game Crucial Winter Range Blacks Fork Blacks Fork

Green River

Bitter Creek

North Platte River

Medicine Bow River

South Platte River

Arikaree River

S. Fork Republican River 

Green River WaKeeney 

0 

6 

3 

5 6 

4 

1 1

Springs 

Hams Fork 

2 3 

Rockies Express/Entrega Pipeline 

New 

Populated 

Pipelines 

(2006-2007) 

Existing 

Pipelines 1

Paralleled 

Overland 

Pass 

Pipeline La Bushton Conway ramie Pump and Washington WaKeeney 

and Me Meter Station Meter Station ter Station Meter Station County Meter Meter Station 

RP 146 RP 717.5 RP 749.4 .5 RP 271.7 Station RP 447.8 RP 606.0 

Major or 

Sensitive 

Waterbodies 

0 188 375 563 749.4

Reference Point

Overland Pass 

Pipeline Project 

Figure 5.1-1

Utility Corridor

Relationships with

Sensitive Resources 

5.1-5
5.2 Cumulative Impacts to Resources 

5.2.1 Climate and Air Quality 

Cumulative fugitive dust (particulate) increases may occur where Overland Pass and Overthrust Wamsutter 

are using the same access road system to construct their projects (Section 5.2.7). Both projects would follow 

state and local requirements for dust control on roads and excavated surfaces. As noted previously, the two 

projects could overlap very briefly in the same work area. 

Overland Pass proposes to use electrical pumps at two proposed locations in Wyoming. As a consequence, 

Overland Pass would not directly contribute to hydrocarbon emissions from its facilities. Indirectly, the 

electricity used by Overland Pass would be produced by coal-fired and natural gas-fired power plants within 

the region. It is anticipated that demands for project electrical power would be met by existing and new 

generating capacity. The specific locations of new generating capacity presently are not known. 

The Echo Springs and Laramie pump stations would be located in rural locations, and 1 mile or more from any 

residential locations. Each pump station would be sited at a new location, and therefore would not interact 

cumulatively with other nearby industrial sources. 

5.2.2 Geology 

5.2.2.1 Mineral Resources 

Nearly all of the proposed pipeline route, and those pipelines that parallel the proposed pipeline route, cross oil 

and gas producing reservoirs. Some of the existing pipelines overlie trona mineral and coal deposits. Other 

mineral sources crossed by the pipelines include gravel, uranium in the Medicine Bow Mountains, and copper, 

gypsum, carbonates, and granite along the flanks of the Laramie Range (BLM 2002b). Although the presence 

of facilities within the corridor that would be occupied by the existing and proposed pipelines would preclude 

extraction of gravel and other minerals, oil and gas production could be accomplished through well pad offsets 

and directional drilling. In most cases, the Overland Pass pipeline generally is adjacent to existing pipelines 

(e.g., Rockies Express/Entrega) in Wyoming. Where the proposed pipeline route is not adjacent to an existing 

pipeline or other utilities, it is due to routing or environmental concerns (e.g., steep terrain, cultural resource 

site) or realigned to join another ROW. 

The amount of near-surface coal deposits precluded from future development due to the proposed pipeline 

route represents a very small increase in the cumulative effects. In fact, a recent study of the coal basins 

underlying the Rawlins Field Office jurisdictional area (BLM 2002b) indicates that coal mining in this area is at 

a distinct economic disadvantage as compared to the Powder River Basin, and that no new mines are 

expected to open to exploit these coal deposits in the foreseeable future. 

5.2.2.2 Geologic Hazards 

Regional seismic hazards, including earthquake ground shaking and subsidence and fault movement sufficient 

to cause damage, are very unlikely (see Section 3.3). Several existing pipelines within the Overland Pass 

corridor cross faults but none of these faults are active. Consequently, cumulative impacts related to fault 

movement and seismic activity are not anticipated. 

5.2.2.3 Paleontological Resources 

The proposed pipeline route would cross approximately 54 miles of BLM Condition 1 geologic units on BLM 

lands in western Wyoming, and 18 miles on the PNG administered by the USFS in Colorado. Condition 1 is 

represented by “areas that are known to contain vertebrate fossils or noteworthy occurrences of invertebrate or 

plant fossils.” Construction of the Overland Pass, Enterprise Western Pipeline, and the Overthrust Wamsutter 

Pipeline would contribute approximately 1.7, 0.3, and 0.4 square miles, respectively, of surface and trench 

disturbance in Condition 1 units. Pre-construction paleontological surveys have been or would be completed 

5.2-1
for approved projects. Trench monitoring would be conducted in areas with high potential for important fossils. 

Fossil material would be recovered and recorded from sites that warrant these investigations. Construction of 

the Overland Pass pipeline would contribute to the cumulative exposure and potential loss of scientifically 

valuable fossils, but construction monitoring would ensure that new scientific information would be collected 

and added to the existing body of knowledge. 

5.2.3 Soils 

The cumulative area of previous soil disturbance within the study area from existing utility projects from Opal, 

Wyoming, to Conway, Kansas, is approximately 222 square miles (Table 5.2-1). Cumulative impacts where 

this line parallels older utilities would be minimal with the effective implementation of BMPs and mitigations. 

More recent utility projects may be in the process of rehabilitation. Potential cumulative impacts could occur 

where these disturbances overlap. These impacts would be highly localized and primarily limited to the time of 

construction and 3 to 5 years following construction with successful reclamation. Cumulative impact would be 

minimized, however, with the effective implementation of erosion control and restoration measures. 

Some soils on previously revegetated ROWs may be re-disturbed by construction on adjacent new pipeline 

ROWs in the future. Pipeline projects scheduled for 2006 and 2007 construction (Overthrust Wamsutter 

Pipeline, Enterprise Western Expansion) would disturb 3.8 and 0.3 square miles where these projects parallel 

the proposed Overland Pass pipeline. The Proposed Action would disturb approximately 10.6 square miles in 

this utility corridor. 

5.2.3.1 Erosion 

Potential cumulative erosion impacts could occur where pipeline construction disturbance areas overlap, or are 

located near each other between RP 0 and RP 329. BMPs for soil management and protection would be 

applied across all ownerships for these pipeline projects. Revegetation mixtures would be applied that are 

appropriate to soil conditions and expected future uses (grazing, wildlife habitat). As a consequence, the 

potential for cumulative erosion increases caused by one or more of these projects is low. 

5.2.3.2 Sensitive Soils 

The primary sensitive soils cumulative impacts issue is the maintenance of agricultural soil productivity where 

these soils have been disturbed by multiple pipelines. Based on STATSGO soils data, the project would cross 

approximately 4.9 miles of hydric soils in Wyoming, 1.1 miles in Colorado, and 1.5 miles in Kansas. These 

areas generally equate to irrigated pasturelands where shallow water tables have been augmented by 

seasonal irrigation. The majority of these areas are located in Albany and Laramie counties, Wyoming. The 

primary cumulative impact issue is to ensure that surface drainage is restored across the proposed Overland 

Pass construction ROW as well as adjacent pipeline ROWs, and to ensure that soil compaction is relieved in 

haylands and pasture. The Overland Pass, Overthrust Wamsutter Pipeline, and Enterprise Western Expansion 

projects have prepared, or would be required to prepare plans to restore and monitor irrigated soils. 

Application of these plans would ensure that agricultural productivity would be maintained indefinitely. 

Soil mixing and compaction could occur on other sensitive soils (shallow, wet, rocky, saline) during 

construction. Where these pipeline corridors overlap and compaction is not mitigated a reduction in infiltration 

and runoff could result. These effects would be addressed on a site-specific basis by the various projects and 

would be minimized by proper implementation of soil protection measures and mitigations for decompaction. 

5.2-2
Table 5.2-1 Overland Pass Project Cumulative Impacts for River Crossings and Streams Containing Fisheries in Wy

Crossing/ Method/ 

Ownership 

Associated Parallel Buried 

Utilities Issues 

Proposed Construc

M

Hams Fork River (RP0.9) Open-Cut Private 

Pipeline 75 feet upstream • Bank armoring – stream channel modification. 

• Channel scouring. • Bank stabilization. 

• Low flow constructio

• Flow bypass flumes 

construction. 

• Channel floor armor

scouring risk. 

• Sand bags to stabili

Blacks Fork River (RP 18.9) Open-Cut Private 

4 pipelines – 50 to 125 feet downstream 

• Downstream sedimentation on resident fisheries 

habitat (Water quality classification 2AB). 

• Bank armoring – stream channel modification. 

• Channel scouring. 

• Low flow constructio

• Flow bypass flumes 

construction. 

• Channel floor armor

scouring risk. 

• Rip rap (rock) to sta

Blacks Fork River (RP 41.3) Open-Cut Private 

3 pipelines – 50 to 100 feet downstream. 

• Downstream sedimentation on resident fisheries 

habitat (Water quality classification 2AB). 

• Existing erosion problem on adjacent ROW 

downstream; bank instability. 

• Channel scouring. 

• Bank armoring – stream channel modification. 

• Low flow constructio

• Flow bypass flumes 

construction. 

• Spoil storage outsid

sediment with rock t

• Rip rap (rock) to sta

Green River (RP 59.3) Flume Federal - USFS 

1 pipeline – approximately 100 feet upstream of the proposed crossing 

• Downstream sedimentation on game fisheries 

habitat (Class 1 Fishery). 

• Migration of kokanee salmon and brown trout 

(spawning period). 

• Channel scouring that could exceed pipe burial 

depth (USFS calculations). 

• Greater pipe burial depth would require greater 

channel spoil removal, resulting in greater stored spoil volume, and greater in-stream sedimentation. 

• Low flow constructio

kokanee salmon mig

• Flow bypass flumes 

construction. 

• Spoil storage outsid

sediment with rock t

• Pull-in pipe section t

channel. 

Backfill trench with rscour protection. 

Bitter Creek (RP 107.2) Open-Cut Private 

4 pipelines, 1 fiber optic cable within 250 feet downstream of proposed crossing. 

• Bank armoring – stream channel modification. • Channel scouring. 

• Low flow constructio

• Excavation of trench 

backhoes (no flow mchannel armoring. 

• Bank stabilization w

5.2-3
Table 5.2-1 Overland Pass Project Cumulative Impacts for River Crossings and Streams Containing Fisheries in Wy

Crossing/ Method/ 

Ownership 

Associated Parallel Buried 

Utilities Issues 

Proposed Construc

M

North Platte River (RP 195.5) Open-Cut State of Wyoming – Game and Fish Commission 

3 pipelines within 300 feet upstream of the proposed crossing. 

• Downstream sedimentation on resident fisheries 

habitat (Water quality classification 2AB). 

• Bank armoring – stream channel modification. 

• Channel scouring. 

• Low flow constructio

• Excavation of trench 

backhoes and use o

• Flow maintained wit

Portadam. 

• Spoil storage within 

• Pull-in pipe section t

within the river. 

• Bank stabilization w

Medicine Bow River (RP 228.1) Open-Cut Private 

4 pipelines, 2 fiber optic cables from 50 to 300 feet downstream of the proposed crossing. 

• Downstream sedimentation on resident fisheries 

habitat (Water quality classification 2AB). 

• Unfavorable crossing location (immediately 

downstream of two actively cutting river bends) because other pipelines are already located in the best crossing locations within this utility corridor. 

• Extensive bank stabilization required to prevent 

river from cutting into the permanent ROW. 

• Low flow constructio

• Dry crossing – sand

downstream of trencriver flow. 

• Sandbags and rip ra

bend immediately u

5.2-4
5.2.4 Water Resources 

5.2.4.1 Surface Water 

Overland Pass proposes to directionally drill the South Platte River and, consequently, there would be no 

direct or cumulative sediment transport increases at this crossing. The proposed pipeline projects would follow 

the FERC procedures and/or BLM stipulations for open-cut crossings of smaller perennial streams and 

intermittently flowing waterbodies. In most cases, erosion control and bank stabilization measures would 

minimize cumulative impacts where the projects cross the same stream channel at the same location. 

Overland Pass proposes to open-cut the crossings of the rivers and larger streams in Wyoming. Table 5.2-1 

provides a summary of: the existing buried utilities located at the same crossing point; proposed crossing 

construction methods; applicant-committed measures to reduce sedimentation from channel excavation and to 

protect stream banks; and additional recommended measures to reduce water quality reductions at individual 

crossings. The crossing methods and adjacent utilities are described in site-specific crossing plans provided to 

BLM by Overland Pass. 

The Enterprise Western Expansion Project would be constructed across the Blacks Fork and Bitter Creek, and 

the Rockies Express/Entrega Project would be constructed across the North Platte and Medicine Bow rivers 

several months to 1 year before Overland Pass would cross the same waterbodies at nearly the same 

locations. Each project would be responsible for stabilizing the stream banks and the channel, and would be 

offset from the Overland Pass ROW. It is unlikely that these prior, but very recent projects would cause new 

channel stabilization requirements for Overland Pass. 

However, there are existing channel and bank stability problems associated with other pipelines that share the 

pipeline corridor proposed for use by Overland Pass (Table 5.2-1). Existing bank erosion and channel 

down-cutting are occurring at the crossing of the Blacks Fork at RP 41.3. It is recommended that a scour 

control plan, and a joint project with the adjacent pipeline owners be undertaken to ensure the long-term 

stability of all adjacent pipelines in the corridor at that location. 

The proposed Overland Pass crossing of the Medicine Bow River is in an unfavorable upstream position 

relative to other pipelines because of the large number of pipelines already installed at the same location. As 

shown in the site-specific crossing plan for this waterbody, extensive bank rip rap on upstream bends would be 

required to stabilize the permanent Overland Pass ROW. Overland Pass has committed to incorporate woody 

vegetation plantings into the bank stabilization plan to supplement rock rip rap. 

Based on currently available schedules, the various projects would not be conducting concurrent hydrostatic 

tests at the same locations and, consequently, these projects would not cause cumulative water withdrawal 

volume reductions on the Green, North Platte, and Laramie rivers. 

The proposed Overland Pass pipeline alignment parallels numerous pipelines and other linear features that 

cross alluvial floodplains and fans that are subject to periodic flooding and scour. Although Overland Pass has 

taken steps to avoid or limit the effects of scour, should an event occur, it could affect one or more other 

pipelines in addition to the Overland Pass pipeline. Potential cumulative damage interactions among pipelines 

as the result of a major channel scouring event are not expected. 

5.2.4.2 Groundwater 

Existing pipeline and other utility projects do not consume groundwater. Both of the pipeline projects currently 

under construction (Overthrust Wamsutter Pipeline, Enterprise Western Expansion) may use groundwater 

from private or municipal sources for dust control or to hydrostatically test their pipeline. The Overland Pass 

Project would utilize an estimated 120.1 acre-feet (39.1 million gallons) of groundwater during construction for 

dust control efforts, hydrostatic testing, and HDD crossings as discussed in Section 4.5.1.2. The proposed 

projects would implement spill containment and control plans as required by the BLM and state agencies. No 

cumulative impacts on groundwater volume or quality from these projects are expected due to the short-term 

5.2-5
nature of withdrawals during different construction timeframes and project procedures to protect groundwater 

resources. 

5.2.4.3 Wetlands 

Cumulative impacts to wetlands would occur where the Rockies Express/Entrega, Enterprise Western 

Expansion, and Overland Pass projects would be co-located between Overland Pass’ RP 0 and RP 329 at the 

Cheyenne Hub. The majority of this disturbance would be in palustrine emergent wetlands and hayfields, 

dominated by grasses and sedges. Within Wyoming, the Overland Pass pipeline would disturb approximately 

55 acres of wetland (primarily hayfields). In the segments co-located with Overland Pass, the Rockies 

Express/Entrega Pipeline would disturb approximately 98 acres. Where they are co-located with Overland 

Pass, the Enterprise Western Expansion would not cause cumulative wetland disturbance impacts. The 

natural gas pipeline projects would apply FERC wetland crossing procedures and/or BLM stipulations, and 

would be subject to conditions contained in USACE 404 permits and state water quality permits. None of the 

wetlands crossed would be permanently filled or drained. Therefore, cumulative effects to wetlands would be 

minor and short-term because of rapid recovery by grasses, sedges, and other herbaceous species. 

5.2.5 Vegetation 

5.2.5.1 Vegetation Communities 

The total amount of vegetation that may be affected by all of the proposed projects is substantial but still 

relatively small compared to the abundance of similar habitat in the project area. While these projects could 

potentially fragment vegetation habitat, this effect would be minimal because no densely forested areas would 

be crossed by the proposed pipelines. This effect would be further reduced by the co-location of many of these 

projects with existing ROWs. All of the projects would include mitigation measures designed to minimize the 

potential for long-term erosion, increase the stabilization of site conditions, and in many cases control the 

spread of noxious weeds, thereby minimizing the degree and duration of the cumulative impact of these 

projects. 

5.2.5.2 Noxious Weeds and Invasive Plant Species 

Based on input from local NRCS offices and the BLM, weed populations already exist, or potentially exist on 

the land adjacent to proposed construction ROWs for the Rockies Express/Entrega, Overthrust Wamsutter, 

Enterprise Western Expansion, and Overland Pass pipeline projects. These projects would apply weed 

controls prior to and during construction, including pre-construction weed control and equipment cleaning. 

These projects also would be responsible for monitoring and controlling weed invasions on federal lands; 

comparable programs have been recommended on private lands, subject to landowner agreements. Based on 

proposed weed control measures and equipment cleaning, these projects would not cumulatively contribute to 

new weed infestations. 

5.2.6 Wildlife, Aquatic Resources, and Special Status Species 

5.2.6.1 Wildlife 

Habitat 

The removal of forest land and shrubland habitats would result in a long-term habitat reduction because the 

regeneration of woody species is slow in the project region. Construction and operation of the proposed 

Overland Pass pipeline would incrementally add to the width of habitat discontinuities within existing utility 

corridors, which may affect the movement of species dependent on these habitats and would cumulatively 

reduce carrying capacity for woodland- and shrubland-dependent species. 

5.2-6
Big Game 

The Overland Pass pipeline would cross elk, mule deer, and pronghorn critical or crucial winter habitats in both 

Colorado and Wyoming, respectively. The incremental surface disturbance contributed by the Overland Pass 

pipeline to the cumulative projects would represent a small fraction (less than 1 percent) of the individual big 

game ranges crossed. Overland Pass, Overthrust Wamsutter Pipeline, and Enterprise Western Expansion 

Pipeline projects have coordinated with the BLM, CDOW, and WGFD to develop revegetation seeding 

mixtures that include shrub, forb, and grass species that are used by big game, as well as other target species. 

The application of these mixtures, followed by ROW monitoring after construction (Appendix C) would ensure 

that there is a long-term effort to restore big game forage in designated critical (Colorado) and crucial 

(Wyoming) winter habitat. 

These projects would cross big game winter ranges in relatively remote areas of southern Wyoming. These 

projects would be subject to winter construction closures depending on severity of the early winter, so that 

wintering big game conflicts would be largely avoided during this season. Big game winter range closures are 

being determined for the Overland Pass Project by the BLM in consultation with the WDGF. 

5.2.6.2 Aquatic Resources 

Overland Pass proposes to open-cut seven streams (Hams Fork River, Blacks Fork River, Bitter Creek, Green 

River, North Platte River, Medicine Bow River, and Laramie River) in Wyoming that contain game fisheries 

(Table 5.2-1). Several of these waterbodies also would be crossed by the Overthrust Wamsutter Pipeline and 

Enterprise Western Expansion pipeline projects several months to 1 year earlier than the Overland Pass 

project. Cumulative waterbody construction impacts would not occur in the same season. Channel armoring 

measures and sediment control measures are proposed by Overland Pass for these crossings to reduce 

downstream sedimentation on fish habitats. As described under water resources, pre-existing bank and 

channel instability associated with previous pipeline projects are contributing to channel morphology changes 

and increased sedimentation downstream of the utility corridor at the Hams Fork and Blacks Fork river 

crossings. 

5.2.6.3 Special Status Species 

With the exception of one bald eagle nest detected on the South Platte River, none of the species discussed 

below would be affected by other pipeline projects within the proposed pipeline cumulative study area. 

Bald Eagle 

Within the cumulative affects area, bald eagles use winter roosts and occasionally nest along the Green, North 

Platte, South Platte, Medicine Bow, Rock Creek, and Laramie rivers. Pipeline crossings for the Rockies 

Express/Entrega Pipeline and Overland Pass pipelines would be subject to construction timing restrictions 

during critical bald eagle use seasons, and would be requested to implement measures to avoid the loss of 

roost or nest trees. No other known projects are scheduled for work locations at these crossings and these 

projects would be constructed in different years. Therefore, these projects would not contribute to cumulative 

impacts to bald eagle winter or nesting habitat, nor would construction activities coincide with bald eagle critical 

use periods along these rivers. 

Black-footed Ferret and Other Prairie Dog Colony Inhabitants (Burrowing Owl, Mountain Plover) 

The Overland Pass, Overthrust Wamsutter, Rockies Express/Entrega, and Enterprise Western Expansion 

pipeline alignments would cross prairie dog colonies between Opal (RP 0.0) and RP 152, east of Rawlins, 

Wyoming. The construction of these projects has and would cumulatively cause surface disturbance in prairie 

dog colonies and potential loss of prairie dog individuals, which are black-footed ferret prey. These projects 

would be subject to pre-construction surveys. If ferrets were sighted, construction would not be authorized until 

the necessary consultation with the USFWS had occurred. If mountain plovers or burrowing owls were sighted 

during pre-construction surveys, construction constraint periods would be established to ensure that fledglings 

5.2-7
leave the areas before construction begins. Based on these measures, no cumulative impacts to these 

species are expected, with the exception of the short-term surface disturbance within prairie dog colonies 

during construction. 

Sage grouse 

Active sage grouse lek (breeding) sites occur within 2 miles of the Overland Pass, Enterprise Western 

Expansion, and Overthrust Wamsutter pipeline routes in Wyoming. Projects would be subject to seasonal 

construction restrictions to avoid critical sage grouse breeding and brood-rearing periods. These projects 

would contribute to incremental increases in the width of the existing pipeline corridors. The combined 

construction ROWs through this segment could be as much as 200 feet, which could more than double the 

pipeline corridor width in some sagebrush habitats. Between Wamsutter and Arlington (a distance of 

approximately 110 miles), the Overland Pass would largely parallel Rockies Express/Entrega and would 

expand a large existing pipeline corridor through Wyoming sagebrush habitats. Reduction in sagebrush cover 

exposes sage grouse to higher predation rates and may limit bird movement across these discontinuities. 

Reduction in sage grouse populations and reductions in use of traditional lek sites have been documented in 

oil and gas well fields in Alberta, Wyoming, and Colorado (Connelly et al. 2000). Other factors, such as 

wildfires, periodic drought, invasion by cheatgrass, and intensive livestock grazing also adversely affect sage 

grouse habitat suitability (Connelly et al. 2004). In summary, the Overland Pass and other regional pipeline 

projects would contribute to the cumulative long-term reduction in, and fragmentation of sage grouse habitat in 

Wyoming by expanding an existing utility ROW. These projects would adhere to seasonal restrictions during 

sage grouse breeding and brood-rearing periods, and therefore cumulative indirect effects from increased 

human activity and noise during construction would not occur. 

5.2.7 Land Use, Recreation, and Aesthetics 

5.2.7.1 Land Use 

Conversion and Construction Effects 

The Overland Pass, Enterprise Western Expansion, Rockies Express/Entrega, and Overthrust Wamsutter 

pipeline projects incrementally would add to the acreage of aboveground oil and gas pipeline facilities in 

Wyoming. Assuming that approximately 300 acres are already dedicated to compressor stations, MLVs, meter 

stations, and pig launchers/receivers, Overland Pass proposes to add 14 acres in Wyoming for aboveground 

facilities. Enterprise Western Expansion Project would require an estimated 9 acres for new aboveground 

facilities (valves, pigging facilities, and interconnections), Rockies Express/Entrega would require 

approximately 17 acres in Wyoming, and Overthrust Wamsutter Pipeline would require 52 acres for its 

aboveground facilities in Wyoming. 

While installation of new pipelines in an existing corridor would incrementally reduce the area available for 

future development, use of established utility corridors concentrates cumulative land use impacts. With the 

exception of a rural residential area between Cheyenne and Laramie (Rockies Express/Entrega and Overland 

Pass), the Overland Pass, Overthrust Wamsutter, and Enterprise Western Expansion projects would not 

cumulatively affect residential land uses. The majority of rural residential lots between Cheyenne and Laramie 

are approximately 40-acre parcels. The existing corridor contains 5 to 6 utilities (pipelines and fiber optic 

cables) in this area. Adding Rockies Express/Entrega and Overland Pass together, the 50-foot permanent 

ROW for 8 utilities across the full width of a 40-acre parcel would be 12.1 acres, or approximately 30 percent 

of the parcel area. However, the existing pipeline corridor pre-dates the subdivision of existing rangeland in 

this area, and owners and new buyers were informed of the pipeline easements in their deeds. 

Special Management Areas 

The Overland Pass and the Rockies Express/Entrega pipelines both cross the Continental Divide Trail at 

RP 178.5. The construction periods of the two projects would not overlap at this location. Both projects would 

5.2-8
maintain recreational user access along this trail by providing short detours, and restoration of existing roads 

and trails. 

5.2.7.2 Visual Resources 

The majority of the proposed pipeline route across federal lands where visual management standards have 

been established are already highly modified by existing utility projects. Two areas where minimum landscape 

modifications would be allowed are located between RP 0 and RP 1.6 (Kemmerer Field Office), and between 

RP 57.0 and RP 60.4 (Rock Springs Field Office), inclusive of the FGNRA. Any future proposed projects that 

would be co-located with the proposed pipeline route at these locations may cause additional cumulative visual 

resource impacts during construction and for a short time thereafter. 

The primary Overland Pass aboveground facilities (Echo Springs and Laramie pump and meter stations) 

would be constructed adjacent to an existing utility corridor. These new facilities would be located in rural 

locations, and therefore would not be viewed by a large number of recreational and highway travelers. 

Cumulative impacts resulting from greater visibility of industrial facilities in natural settings are not expected. 

5.2.8 Cultural Resources 

Records searches and pedestrian surveys have been completed in Wyoming, Colorado, and Kansas. There is 

a potential for sites eligible to the NRHP to be affected by pipeline projects constructed adjacent to each other 

in the same utility corridor. Effects on eligible sites by the individual projects would be determined 

independently through reviews by the BLM and the SHPOs of the individual states. In some instances, the 

cumulative surface disturbance of multiple projects in the same corridor may require rerouting of one or more 

projects to minimize surface disturbance effects on cultural resources. 

5.2.9 Social and Economic Conditions 

The Overland Pass pipeline and other pipeline projects may be constructed in a similar timeframe. While 

detailed schedules are not available, it is likely that the Overthrust Wamsutter Project could overlap with the 

Overland Pass construction timeframe and the two projects would be constructed in the same general area. 

Assuming approximately 1 mile of pipeline construction per spread was completed each day, the workforces of 

the two projects could broadly overlap over a period of several weeks. The Rendevous pipeline and Kanda 

Lateral also may be constructed in late 2007, and the workforces for these projects may place demands on 

local infrastructure (temporary housing, other services). The potential for the maximum cumulative workforce 

likely would occur in the vicinity of Green River and Rock Springs, Wyoming. Based on current high levels of 

oil and gas activity in this region, it is expected that there may be a shortage of temporary housing for non-local 

workers, resulting in longer employee commutes, or the requirement for contractors to obtain more temporary 

housing in the vicinity of the pipeline spreads. There also may be increased demands on local emergency 

services, based on the large number of projects underway at the same time, and the large distances to be 

traveled for emergency response. 

The majority of the Overland Pass and Overthrust Wamsutter work areas are in rural areas, with good access 

to I-80 across Wyoming. Cumulative traffic impacts are not expected except where multiple projects are being 

constructed simultaneously, such as the vicinity of Kanda and Granger in western Wyoming. These cumulative 

impacts would be short-term as pipeline spreads move away from congested areas. 

The Overland Pass and Overthrust Wamsutter projects would follow transportation plans to manage 

construction vehicles, and would follow standard measures for fence repair, provision of temporary gates, and 

provision of temporary crossings for livestock. Equipment turning onto and off state highways and access 

roads may require flagmen and other controls to limit the risk of accidents on public roads. Both projects would 

be required to obtain local crossing permits for county roads, which would define weight limits and 

maintenance standards. The BLM and USFS have defined minimum standards for maintenance of existing 

roads, and construction and operation of any new permanent roads on BLM- or USFS-administered land. 

5.2-9
The construction workforces for projects occurring in the same timeframe would contribute to short-term 

increases in local sales tax revenues, and long-term increases in the property tax base. Few long-term 

employees would be needed to operate these new pipelines, and therefore no long-term impacts to 

employment and demands on local services are expected. 

5.2.10 Public Health and Safety 

As discussed previously, no cumulative operational safety impacts are expected among pipelines and other 

facilities located in the same general utility corridor because of the spacing between pipelines, the depth of soil 

cover, and requirements to meet USDOT Minimum Federal Safety Standards in 49 CFR Part 195 and 

43 CFR 2886.10. 

5.2-10