SUBJECT: The U.S. Army Corps of Engineers, Sacramento District, (Corps) is evaluating a permit application to construct the City of Henderson - Duck Creek Flood Control Project, which would result in impacts to approximately 0.97-acre of waters of the United States. 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: Mr. Albert Jankowiak
City of Henderson
240 Water Street
Henderson, Nevada 89009
LOCATION: The 0.97-acre linear site is located on Duck Creek, in Section 6, Township 22 South, Range 62 East, Mount Diablo Meridian, Latitude 36.06815°, Longitude -115.08857°, Henderson, Clark County, Nevada, and can be seen on the NV-LAS VEGAS SE USGS Topographic Quadrangle.
PROJECT DESCRIPTION: The applicant is proposing to construct a flood control project on a 2,620-linear-foot segment of Duck Creek from Sandhill Road to downstream of Sunset Road. The proposed action area is currently a graded earthen channel. The right-of-way (ROW) width is 140 feet for most of this segment of the Duck Creek channel. The proposed improvements include construction of a concrete trapezoidal channel that would have a bottom width of 35 feet with 2 height to 1 vertical (2H:1V) side slopes ranging between 9 and 13 feet in height (see Figure 2).
The existing concrete channel upstream of Sandhill Road is approximately 12 feet deep with 30‐foot bottom width and 1.5:1 side slopes. This section would transition into the proposed section that is 9 feet deep with 35‐foot bottom width and 2:1 side slopes. A 50‐foot long transition is proposed at this location. The proposed channel would be 12‐feet deep on the north side of the upstream reach because of a proposed maintenance ramp and super‐elevation concerns in this area.
A retaining wall (up to 4.5‐feet high) would be constructed on the south side through the most upstream reach. Additionally, a retaining wall (up to 4‐feet high) would also be constructed on the south side through the 100‐foot ROW section.
The Proposed Action would also include a 12‐foot maintenance access road along the top of the northern channel bank and a 5‐foot man-way along the southern channel bank. The access road and the man-way would be discontinuous and would terminate at each bridge.
Downstream of Sunset Road, the existing channel has an earthen bottom and gabion mattress lining on the side slopes. The existing channel has a 45‐foot bottom width with 2:1 side slopes. This rougher
channel section downstream of Sunset Road causes a hydraulic jump to form. Because the location of the hydraulic jump is very sensitive to the channel characteristics, additional design elements would be implemented. The channel would be widened to match the existing channel bottom width from approximately 90 feet upstream of the Sunset Road Bridge. The channel would be deepened to approximately 12 feet up-steam and downstream of the Sunset Road Bridge and a 40-foot section downstream of the concrete lined channel would be armored with 3‐foot gabion baskets as it transitions back into the existing channel.
Construction of the project would increase the design capacity of the existing channel from 5,385 cubic feet per second (cfs) to 5,661 cfs, an increase of approximately 5 percent. The Federal Emergency Management Agency Special Flood Hazard Area (Zone AE) associated with the Duck Creek through the project reach is contained through the channel except at a few locations where the floodplain encroaches into the private property adjacent to Duck Creek. The flood zone would be fully contained in the proposed channel and the floodplain encroachment into the adjacent private property would be eliminated after the completion of the project.
Based on the available information, the overall project purpose is to improve channel conveyance capacity in order to safely convey the 100-year flood flows through the adjacent urban area. The project is designed to further prevent erosion and degradation within the channel and to protect existing infrastructure from damage due to erosion and flood events. The work proposed for Duck Creek would remove the adjoining properties from the flood hazard zone. The project would also alleviate the need for post event maintenance and repairs. The applicant believes there is a need for the project based on public safety and protection of existing infrastructure. The attached drawings provide additional project details. The Corps believes the basic need for the project is improve flood control facilities.
Environmental Setting. There is approximately 0.97-acre of stream channel within the project area. The site is characterized by a perennial stream that has been channelized and riprapped through an urban environment. Duck Creek historically was most likely a seasonal or intermittent stream that now is perennial fed by urban runoff. Duck Creek is a tributary to the Las Vegas Wash, which flows into Lake Mead. No wetlands were identified in the project area. The project would result in modification of Duck Creek, including placement of fill below the ordinary high water mark.
Alternatives. The applicant has provided information concerning project alternatives. According to the applicant , several concrete trapezoidal channel sections with varying bottom widths (narrow and wide) with 2:1 side slopes were evaluated. A rectangular concrete channel 35 feet wide and 10 feet deep was also evaluated. This alternative would be narrower than the trapezoidal option and would provide more open space for future trail improvements and potential landscaping but the amount of concrete, steel reinforcement and backfill would increase the construction costs by approximately 45 percent. A riprap lined section was evaluated but the calculated flow depth would be higher than the allowable depth under the existing bridges. A wider trapezoidal section, to lower the flow depth, would also not be possible because of the limited ROW. Gabion and articulated concrete block channel linings were evaluated but found to result in unstable hydraulic conditions. The applicant determined the 35-foot bottom width and 9-foot deep trapezoidal channel to be the desirable alternative because this alternative would fulfill all the project goals, would be compatible with the existing bridges, and would require the least amount of backfill between the existing and proposed grades, with reduced costs compared to narrower and deeper trapezoidal geometry. Additional information concerning project alternatives may be available from the applicant or their agent. Other alternatives may develop during the review process for this permit application. All reasonable project alternatives, in particular those which may be less damaging to the aquatic environment, will be considered.
Mitigation. The Corps requires that applicants consider and use all reasonable and practical measures to avoid and minimize impacts to aquatic resources. If the applicant is unable to avoid or minimize all impacts, the Corps may require compensatory mitigation. The applicant has pre-purchased credits at an In-Lieu Fee program to offset project impacts.
OTHER GOVERNMENTAL AUTHORIZATIONS: Water quality certification or a waiver, as required under Section 401 of the Clean Water Act from the Nevada Department of Environmental Quality is required for this project. The applicant has indicated they have applied for certification.
HISTORIC PROPERTIES: Based on the available information (including applicant's report entitled “Duck Creek, Sunset Road to Sandhill Road Flood Control Project 404 Permit, Cultural Resources Record Search and Information Scoping Results”), cultural resources were identified near the project's area of potential effect. The Corps will initiate consultation with the State Historic Preservation Officer under Section 106 of the National Historic Preservation Act, as appropriate.
ENDANGERED SPECIES: The project will not affect any Federally-listed threatened or endangered species or their critical habitat that are protected by the Endangered Species Act.
ESSENTIAL FISH HABITAT: The proposed project will not adversely affect Essential Fish Habitat (EFH) as defined in the Magnuson-Stevens Fishery Conservation and Management Act.
The above determinations are based on information provided by the applicant and our preliminary review.
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-2012-00745-SG must be submitted to the office listed below on or before May 17, 2013.
Patricia McQueary, Project Manager
US Army Corps of Engineers, Sacramento District
196 East Tabernacle Street, Room 30
St. George, Utah 84770
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 Patricia McQueary, telephone 435-986-3979, or email Patricia.L.McQueary@usace.army.mil.
Attachments: 29 drawings