CESPK-RD-C
SUBJECT: The U.S. Army Corps of Engineers, Sacramento District (Corps), is evaluating a permit application for the Federal Highway Administration (FHWA) to armor 1,500 linear feet of bank on the Yampa River within Dinosaur National Monument. The nature and extent of impacts are more specifically described below. This notice is to inform interested parties of the proposed activity and to solicit comments.
AUTHORITY: This application is being evaluated under Section 404 of the Clean Water Act for the discharge of dredged or filL material in waters of the United States.
APPLICANT: Federal Highways Administration, Mr. Matt Ambroziak, P.E., Project Manager, 12300 West Dakota Avenue, Suite 380A, Lakewood, Colorado 80228-2583, Phone: (720) 963-3619
AGENT: CH2M HILL, Mr. Matt Kizlinski, 9191 South Jamaica Street, Englewood, CO 80112 , Phone: (720) 286-0472, Email: Matt.Kizlinski@CH2M.com
LOCATION: The project area is located on the south bank (river left) of the Yampa River, immediately north of Deerlodge Road at milepost 9.5, located at 40.4383° north, -108.4733° west, Sixth Principal Meridian, Sections 25 and 26, Township 6 North, Range 99 West, within Dinosaur National Monument, Moffat County, Colorado. See Attachment 1
PROJECT NEED AND PURPOSE: The purpose is to stabilize a 1,500 linear foot section of eroding river bank in order to prevent damage to Deerlodge Road. Deerlodge Road is adjacent to this section of the Yampa River and is the only entrance to the eastern portion of Dinosaur National Monument, providing access to the public campground, ranger station, a boat launch site, BLM lands, and private lands. Based on available information, the Corps has determined the basic project purpose is bank stabilization.
PROJECT DESCRIPTION: The applicant is proposing to install approximately 5,800 cubic yards of Class VIII rip rap (30‐inch diameter) below the Ordinary High Water Mark (OHWM) of the south bank (river left) of the Yampa River, resulting in an impact to 0.82 acres of open water. The project will not fill or otherwise impact wetlands. See Attachments 2 and 3.
ADDITIONAL INFORMATION:
Background and History: The Monument was created by presidential proclamation on October 4, 1938 as an 80-acre Monument to preserve the extensive fossil deposits at dinosaur quarry. In 1951, the original 80-acre Monument was enlarged by presidential proclamation to administer lands for preservation of natural resources and public use. This addition contained the canyons and viewsheds of the Green and Yampa rivers. Additional land was added in 1960, enlarging the Monument and providing for new access roads. Currently, the Monument encompasses 211,141 acres.
In 2003, Dinosaur National Monument attempted to stabilize the south bank of the Yampa River
adjacent to Deerlodge Road by burying riprap in a trench between the roadway and the
riverbank. However, in 2011, above average snowmelt and runoff caused substantial bank
erosion due to the migration of the Yampa River along Deerlodge Road and damaging the
previous bank stabilization work. The Yampa River has encroached to within approximately 50
feet of the edge of the pavement in this area.
Alternatives: The following list of alternatives has been provided by the applicant, and has not been vetted or otherwise evaluated at this time. The Corps will perform an alternatives analysis of both onsite and offsite alternatives as part of the project evaluation.
Alternative 1 (No Action): No bank stabilization work would be performed and Deerlodge road would remain at risk for damage/recapture as the south bank of the Yampa River continues to erode.
Alternative 2 (Applicant preferred): The applicants preferred alternative, as described under Project Description, above.
Alternative 3 (Stabilize with Soil Cement): As an alternative to rip rap, soil cement was evaluated. Soil cement as bank protection would require a completely dry work requiring dewatering. Soils to make the soil‐cement would be imported and the soil‐cement mixture would be made off‐site and transported to the project area. This bank stabilization method would require excavation of approximately 19,100 cubic yards of native streambed material, which would be replaced with soil cement to form the toe of the slope and stair‐step construction. Approximately 6,100 cubic yards would be backfilled to cover the toe and about 13,000 cubic yards of the streambed material would be hauled away. While this alternative would have the same impacts on wetlands as the proposed alternative (i.e., no impacts to wetlands), it would involve a greater excavation within the Yampa River and a longer construction duration within the channel, and therefore was eliminated. Additionally, this alternative required a significant amount of material transported to and from the site.
Alternative 4 (Buried Rip-Rap): An alternative using buried rip rap was developed that would avoid impacts to the Yampa River channel. This method would bury the stabilizing rip rap a minimum of eight feet from the existing river embankment. The river would continue to erode the bank, and eventually expose the rip rap forming a rip rap‐lined embankment. This approach would require the roadway to be
relocate to south and new ROW acquired. While this alternative would avoid direct impacts to the river, erosion would be allowed to continue with the expectation that the bank will erode as predicted, reach the buried rip rap, and form a stable bank. A version of this approach was attempted in 2003 and has been only partially successful in stabilizing the bank. The design alternative was similar in concept to what was done in 2003, but the limits of the project and the volume of riprap for the current design were greater. It was decided it would be better to stabilize the bank in its present location where the solution can be designed and installed with the best prospect of success. Additionally, this buried rip rap approach would require ROW acquisition and relocation of the road to the south in an already narrow corridor between the river and unstable geology in the hills to the south. If the buried rip rap were to fail again, it would require either another bank stabilization effort or rerouting of the road. The NPS indicated that relocating the road again was undesirable. Because of the uncertainty of success and potential for additional stabilization projects, this alternative was eliminated. This alternative also allows a significant portion of the existing bank to continue to erode before it is protected.
Alternative 5 (Combination of Exposed/Buried Rip-Rap): The bank stabilization design in the 30 percent stage presented a design which extended onto private ROW. In an effort to minimize the need to acquire ROW and minimize impacts to the river, an alternative design was developed. This design consisted of a combination of exposed rip rap and buried rip rap. The rip rap would be exposed nearest to the roadway encroachment and then become buried at the eastern and western ends so that the improvements remained in the ROW. As scour continues along the buried improvements, the buried rip rap would become exposed and the embankment would remain stable. However, this would allow a
significant portion of the existing bank to erode prior to reaching the stabilization at each end.
The downstream length required for the solution on the private property (1.5 times the channel width, or 450 feet) could not be achieved. This length is required to “train” the flow in a straight direction after a bend. Once the buried rip rap is exposed, the flow exiting the bend would not be directed at the main channel, and erosion would continue beyond the end limit of the placed riprap, and likely eventually threaten to compromise the road further downstream. This alternative was eliminated because of the temporary nature of the repair, in that while it would protect the road currently being threatened, it would have greater impacts upstream and downstream where the river would continue to erode until it reached the stabilized bank. This could potentially require yet another stabilization and/or realignment project, which from an impact and cost standpoint, are undesirable. This alternative also allows a significant portion of the existing bank to continue to erode before it is protected.
MITIGATION: The Corps requires that applicants consider and use all reasonable and practical measures to avoid and minimize impacts to aquatic resources. Wetlands do not exist within the project area, and the project will result in a stabilized bank and reduction in downstream sedimentation. Accordingly, a requirement for compensatory mitigation is not anticipated.
OTHER GOVERNMENTAL AUTHORIZATIONS: Water quality certification or a waiver, as required under Section 401 of the Clean Water Act from the Colorado Department of Public Health and Environment (CDPHE), is required for this project. The applicant has applied for water quality certification.
HISTORIC PROPERTIES: The State Historic Preservation Officer (SHPO) concurred with the National Park Service determination that this project will result in no historic properties affected by letter dated December 24, 2012.
ENDANGERED SPECIES: A determination of may affect, not likely to adversely affect, was made by the National Park Service for the Colorado pikeminnow, razorback sucker, humpack chub, and bonytail. The United States Fish and Wildlife Service (USFWS) concurred with this determination, by letter dated February 11, 2013.
EVALUATION FACTORS: The decision whether to issue a permit will be based on an evaluation of the probable impacts, including cumulative impacts, of the described activity on the public interest. That decision will reflect the national concern for both protection and utilization of important resources. The benefit, which reasonably may be expected to accrue from the described activity, must be balanced against its reasonably foreseeable detriments. All factors which may be relevant to the described activity will be considered, including the cumulative effects thereof; among those are conservation, economics, aesthetics, general environmental concerns, wetlands, historic properties, fish and wildlife values, flood hazards, floodplain values, land use, navigation, shoreline erosion and accretion, recreation, water supply and conservation, water quality, energy needs, safety, food and fiber production, mineral needs, consideration of property ownership and, in general, the needs and welfare of the people. The activity's impact on the public interest will include application of the Section 404(b)(1) guidelines promulgated by the Administrator, Environmental Protection Agency (40 CFR Part 230).
The Corps is soliciting comments from the public, Federal, State, and local agencies and officials, Indian tribes, and other interested parties in order to consider and evaluate the impacts of this proposed activity. Any comments received will be considered by the Corps to determine whether to issue, modify, condition, or deny a permit for this proposal. To make this decision, comments are used to assess impacts on endangered species, historic properties, water quality, general environmental effects, and other public interest factors listed above. Comments are used in the preparation of an Environmental Assessment and/or an Environmental Impact Statement pursuant to the National Environmental Policy Act. Comments are also used to determine the need for a public hearing and to determine the overall public interest of the proposed activity.
SUBMITTING COMMENTS: Written comments, referencing Public Notice SPK-2013-00379, must be submitted to the office listed below on or before June 27, 2013.
Steve Moore, Project Manager
US Army Corps of Engineers, Sacramento District
Colorado West Regulatory Branch
400 Rood Avenue, Room 224
Grand Junction, CO 81501
Phone: 970-243-1199, ext. 13
Email: Stephen.A.Moore@usace.army.mil
The Corps is particularly interested in receiving comments related to the proposal's probable impacts on the affected aquatic environment and the secondary and cumulative effects. Anyone may request, in writing, that a public hearing be held to consider this application. Requests shall specifically state, with particularity, the reason(s) for holding a public hearing. If the Corps determines that the information received in response to this notice is inadequate for thorough evaluation, a public hearing may be warranted. If a public hearing is warranted, interested parties will be notified of the time, date, and location. Please note that all comment letters received are subject to release to the public through the Freedom of Information Act. If you have questions or need additional information please contact the applicant or the Corps' project manager Steve Moore at 970-243-1199 ext. 13, or by email at Stephen.A.Moore@usace.army.mil.
Attachments:
1. Vicinity Map
2. Overhead Plan
3. Section Plan