CACHE LA POUDRE RIVER AT GREELEY, COLORADO
DRAFT FEASIBILITY REPORT AND ENVIRONMENTAL ASSESSMENT
April 2014
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CACHE LA POUDRE RIVER AT GREELEY, COLORADO
DRAFT FEASIBILITY REPORT AND ENVIRONMENTAL ASSESSMENT
EXECUTIVE SUMMARY
This Cache la Poudre integrated feasibility study and environmental assessment includes both flood risk management and ecosystem restoration. The project area is located along the Cache la Poudre River near Greeley, in the northeastern part of Colorado, north of Denver. Most of the land surrounding Greeley is used for agricultural purposes, and gravel mining occupies a significant portion of the floodplain. The project reach extends from the confluence of the Cache la Poudre and South Platte Rivers, 17 miles upstream along the Cache la Poudre River, through the northern corporate limits of the city of Greeley.
Significant Greeley flooding is likely during events above the 5 percent annual chance of exceedance (ACE) (20-year event), depending on location. Under current conditions, approximately 450 structures, mostly residential, are damaged in the 0.2 percent ACE flood. Approximately 250 structures, over half of which are residential, are damaged in the 1 percent ACE flood event. Ongoing channel sedimentation and increased discharges will likely cause future floods to occur more frequently.
This study explored opportunities for levees, flow diversions, storage, and nonstructural measures to reduce flood risks, and evaluated numerous conceptual plans in those categories. None of the structural measures were found to be economically feasible. Nonstructural measures are feasible for 64 structures, of which 44 are residential and 20 are nonresidential. The measures for residential houses would include elevating houses in place, removing at-risk basements, and one buyout of a structure which is located within the floodway. Nonstructural measures would include dry or wet flood proofing commercial structures and placing a nonstructural floodwall around a group of three county buildings. All individual structures with benefit/cost ratios (BCRs) exceeding 1.0 are included in the proposed plan. These are distributed over a 9-mile reach, with 52 of the structures concentrated in one neighborhood. The optimal level of flood risk reduction would be for the 0.2 percent ACE (500-year) flood. The total first cost would be $5.9 million, and the aggregate BCR with risk and uncertainty is 2.03. Participation during implementation would be voluntary.
The Cache la Poudre River is a nationally significant ecosystem. In particular, the Cache la Poudre provides critical habitat linkages between the Rocky Mountains and plains river systems and habitats. Especially critical habitats in the Rocky Mountain Front Range are riparian corridors that provide migration, breeding, and rearing habitat for numerous bird and native species. Riparian areas account for only one to three percent of Colorado’s land area according
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to the U.S. Fish and Wildlife Service and Colorado Parks and Wildlife; yet they form essential habitat for over 50 percent of Colorado’s bird species. This region has experienced significant habitat losses including reductions of over 70 percent for riparian forests and over 50 percent of wetlands state-wide with even higher percentages in urban areas. Ecosystem problems include fragmentation of regionally-critical riparian migratory bird habitat; wetland loss and degradation; an incised and channelized stream; loss of river/floodplain interaction; unnatural, riprapped streambanks; and invasive species with low habitat value. Ecosystem restoration opportunities are enhanced by large areas of floodplain land available for restoration; and public ownership of some such lands. Restoration of wetland and riparian habitats can provide critical floodplain and river corridor connections, habitat for state-listed threatened and endangered species, and international migratory bird habitat.
Floodplain areas covering 8,400 acres in the 17-mile study reach were assessed to identify best opportunities to restore riparian and wetland habitats benefitting migratory birds and other native species. Screening out the Greeley-Weld County Airport reach and a problematic gravel pit reach eliminated approximately seven miles. Prioritization of remaining, potentially available areas identified approximately 460 acres in nine areas spanning eight miles. In these areas, opportunities were assessed for diverting river water or stormwater onto floodplain areas, excavating to restore river connections to oxbows or to restore meanders, excavating into or near groundwater, seeding and planting, and removal of exotic vegetation. Combinations of these were evaluated in each of the nine areas. One of the nine areas was eventually screened out as well due to high real estate costs and potential for contaminated soils. Alternative plans within each of the other eight areas were evaluated and compared to one another using the cost- effectiveness/incremental cost analysis technique. The resulting proposed plan consists of an alternative at each of the eight areas, a total of approximately 446 acres. Within these total acres, ecological lift is accomplished by increasing riparian forest from 80 acres to 198 acres and wetlands from 11 acres to 179 acres. It would reduce acres of ruderal rangeland, other agricultural land, and disturbed areas an equivalent amount, approximately 286 acres. The plan calls for excavation, grading, plantings, and seeding, at a first cost of $29.1 million, including real estate interests.
Recreation related to the ecosystem restoration was evaluated and was found to be justified. The proposed recreation plan involves features at five of the eight restoration areas. It would include roughly seven miles of trails, ½-mile of wetland boardwalk, two trailheads with parking lots, shelters, and signage, with a first cost of $771,000.
Greeley served as the cost-share sponsor of this study, and would be the cost-share sponsor for implementation. The U.S. Army Corps of Engineers has coordinated with Greeley throughout the study, and Greeley has endorsed the proposed plan and indicated its intent to sponsor implementation of the project.
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CACHE LA POUDRE RIVER AT GREELEY, COLORADO DRAFT FEASIBILITY REPORT AND ENVIRONMENTAL ASSESSMENT
Table of Contents 1. STUDY AUTHORITY ...... 1 2. STUDY PURPOSE AND SCOPE ...... 1 3. LOCATION AND SPONSORSHIP ...... 2 4. PROBLEMS AND OPPORTUNITIES (PURPOSE OF AND NEED FOR ACTION) ...... 5 5. PRIOR STUDIES, REPORTS, AND EXISTING PROJECTS...... 5 6. EXISTING AND FUTURE WITHOUT-PROJECT CONDITIONS (PURPOSE OF AND NEED FOR ACTION, AFFECTED ENVIRONMENT) ...... 7 6.1 History of Flooding ...... 7 6.2 Hydrologic Conditions ...... 9 6.3 Hydraulic Conditions ...... 13 6.4 Floodplain Management ...... 14 6.5 Geotechnical and Soil Conditions ...... 15 6.6 Fisheries ...... 16 6.7 Riparian Habitat ...... 16 6.8 Vegetation ...... 18 6.9 Wetlands ...... 19 6.10 Wildlife ...... 20 6.11 Federally and State-Listed Species ...... 20 6.12 Hazardous, Toxic and Radioactive Waste (HTRW) Considerations ...... 22 6.13 Air Quality ...... 23 6.14 Cultural Resources ...... 23 6.15 Social and Economic Resources ...... 23 6.16 Recreation ...... 27 7. PLANNING CONSTRAINTS ...... 27 8. FRM PLAN FORMULATION ...... 27 8.1 FRM OBJECTIVES ...... 27 8.2 FRM MEASURES ...... 28 8.3 FRM PRELIMINARY SCREENING ...... 28 8.4 FRM PLAN EVALUATIONS ...... 30
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8.5 FRM COMPARISONS – OPTIMIZATION ...... 41 8.6 FRM TENTATIVELY SELECTED PLAN / NATIONAL ECONOMIC DEVELOPMENT PLAN ...... 42 9. ECOSYSTEM RESTORATION (ER) PLAN FORMULATION ...... 44 9.1 ER OBJECTIVES ...... 44 9.2 ER MEASURES ...... 45 9.3 ER OPPORTUNITIES AND SCREENING ...... 46 9.4 ER ALTERNATIVE SITE PLANS ...... 50 9.5 ER ALTERNATIVE EVALUATIONS AND COMPARISONS ...... 53 9.6 ER TENTATIVELY SELECTED PLAN / NATIONAL ECOSYSTEM RESTORATION (NER) PLAN ...... 55 10. RECREATION PLAN FORMULATION ...... 56 10.1 RECREATION GOALS AND OBJECTIVES ...... 57 10.2 RECREATION OPPORTUNITIES AND MEASURES ...... 57 10.3 RECREATION PLAN DEVELOPMENT AND EVALUATION ...... 59 10.4 RECREATION Tentatively Selected Plan ...... 61 11. DESCRIPTION OF TENTATIVELY SELECTED PLAN (PROPOSED ACTION) ... 61 11.1 PLAN COMPONENTS ...... 61 11.2 PLAN FEASIBILITY ...... 63 11.3 RISK MANAGEMENT ...... 65 11.4 DESIGN AND CONSTRUCTION CONSIDERATIONS ...... 67 11.5 REAL ESTATE CONSIDERATIONS ...... 68 11.6 OPERATION AND MAINTENANCE CONSIDERATIONS ...... 69 11.7 SUMMARY OF ENVIRONMENTAL AND SOCIAL EFFECTS (ENVIRONMENTAL EFFECTS) ...... 69 12. PLAN IMPLEMENTATION ...... 86 12.1 INSTITUTIONAL, LEGAL, AND POLICY REQUIREMENTS AND ISSUES ...... 86 12.2 COSTS AND COST-SHARING ...... 87 12.3 DIVISION OF PLAN RESPONSIBILITIES ...... 89 12.4 FRM IMPLEMENTATION ...... 90 12.5 ER IMPLEMENTATION ...... 91 12.6 RECREATION PLAN IMPLEMENTATION ...... 92 12.7 OPERATION, MAINTENANCE, REPAIR, REPLACEMENT, AND REHABILITATION ...... 92
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12.8 SCHEDULE ...... 93 13. COORDINATION, PUBLIC AND AGENCY VIEWS & COMMENTS ...... 93 14. QUALITY REVIEWS ...... 95 15. RECOMMENDATIONS ...... 95 16. BIBLIOGRAPHY ...... 97
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LIST OF TABLES Table 1. EA headings and corresponding report sections ...... 2 Table 2. Cache la Poudre River basin gaging station data ...... 9 Table 3. Data from climatological gaging station ...... 10 Table 4. Comparison of existing and future (2035) conditions’ peak discharges (cfs) ...... 11 Table 5. Volume probability – Bluff Line gage near Fort Collins and at Greeley ...... 12 Table 6. Existing and future-without project water surface elevations (ft) ...... 14 Table 7. Inventoried plant communities ...... 18 Table 8. Volumes needed to reduce peak flows to a lower return period ...... 31 Table 9. Benefit/cost calculations for setback levees ...... 35 Table 10. Optimization data for three flood levels ...... 42 Table 11. Habitat types within the study area ...... 46 Table 12. Relating objectives to measures and performance criteria ...... 47 Table 13. Criteria in identification of primary opportunities for restoration ...... 49 Table 14. Descriptive summary of alternative site plans ...... 51 Table 15. Best buy plans in order of outputs and costs ...... 54 Table 16. Without project (WO) and with project (WP) habitat, year 50 ...... 56 Table 17. Summary of features by area ...... 59 Table 18. Recreation facilities cost estimate by area (FY2014) ...... 60 Table 19. Summary of benefits and costs by area ...... 61 Table 20. Comparison of proposed plan to planning criteria, objectives, and constraints ...... 64 Table 21. FRM project costs and accomplishments ...... 87 Table 22. ER and REC project costs and accomplishments ...... 88 Table 23. FRM fully funded estimate ...... 88 Table 24. ER and REC fully funded estimate ...... 89 Table 25. Total estimated project costs and cost shares ...... 89 Table 26. Proposed schedule for Greeley GI study completion ...... 93 Table 27. Quality and vertical team reviews ...... 95
LIST OF FIGURES Figure 1. Project location map ...... 3 Figure 2. Cache la Poudre River study area ...... 4 Figure 3. Cache la Poudre River basin...... 10 Figure 4. 90-year history of annual peak runoff volumes ...... 11 Figure 5. Flow and volume probability relationships – existing and future conditions ...... 12 Figure 6. Palustrine emergent wetland dominated by cattails, rushes and sedges ...... 19 Figure 7. Wetland dominated by reed canary grass ...... 20 Figure 8. Palustrine shrub-scrub wetlands ...... 20 Figure 9. State special concern yellow-billed cuckoo ...... 22 Figure 10. Floodway levee alignments ...... 33 Figure 11. Setback levee alignments ...... 33 Figure 12. Samples of a residence elevation in place ...... 36 Figure 13. Samples of floodwall and dry flood proofing...... 39 Figure 14. Concentration of TSP structures near Rodarte neighborhood ...... 43 Figure 15. 0.2 percent (500-year) ACE floodplain and structures included in the TSP ...... 43 Figure 16. Greeley - Weld County Airport reach ...... 48
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Figure 17. Gravel pit area avoided ...... 48 Figure 18. Primary (red) and secondary (yellow) opportunity sites and designated Area A...... 49 Figure 19. Nine areas identified as best opportunities for ecosystem restoration ...... 50 Figure 20. Example of site plan alternatives – Area A ...... 50 Figure 21. Incremental cost display of best buy plan combinations ...... 55 Figure 22. Bar graph of NER Plan change in acres of desired habitat types ...... 56 Figure 23. Alignment of Poudre River Trail near ecosystem restoration areas ...... 58 Figure 24. Proposed walking trails in Areas A, B, and C ...... 58 Figure 25. Proposed walking trails in Areas H and I ...... 59 Figure 26. All proposed FRM, ER, and recreation areas in the plan ...... 63
LIST OF APPENDICES
A HYDROLOGY B HYDRAULICS C NONSTRUCTURAL FLOOD RISK MANAGEMENT D GEOTECHNICAL ENGINEERING E ENVIRONMENTAL ANALYSIS E1 Restoration formulation E2 Compliance F ECONOMICS G RECREATION H COST ENGINEERING I REAL ESTATE J CULTURAL RESOURCES K PUBLIC INVOLVEMENT
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LIST OF ABBREVIATIONS
AAE HU average annual equivalent habitat units ACE annual chance of exceedance ASA/CW Assistant Secretary of the Army for Civil Works BCR benefit/cost ratio CAA Clean Air Act CE/ICA cost effectiveness/incremental cost analysis cfs cubic feet per second CIAA cumulative impact assessment area CNHP Colorado National Heritage Program CPW Colorado Parks and Wildlife CWA Clean Water Act dB decibels dBA decibels A-weighted scale DFIRM Digital Flood Insurance Rate Map EA environmental assessment EAD expected annual damages EGM Economic Guidance Memorandum EIS environmental impact statement EO Executive Order EOP environmental operating principals EPA Environmental Protection Agency EQ environmental quality ER ecosystem restoration ESA Endangered Species Act FAA Federal Aviation Administration FEMA Federal Emergency Management Agency FIRM Flood Insurance Rate Map FIS Flood Insurance Study FONSI Finding of No Significant Impact FPMP Floodplain Management Plan FRM flood risk management FWCA Fish and Wildlife Coordination Act FY fiscal year GI General Investigation HEC-FDA Hydrologic Engineering Center-Flood Damage Reduction Analysis HEC-RAS Hydrologic Engineering Center-River Analysis System HEP habitat evaluation procedures HMGP Hazard Mitigation Grant Program HSI Habitat Suitability Index HTRW hazardous, toxic and radiological waste HU habitat units IDC interest during construction
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IEPR independent external peer review IPR in-progress review IWR Institute for Water Resources LERRD lands, easements, relocations, rights of way, and disposal areas msl mean sea level NED National Economic Development NEPA National Environmental Policy Act NER National Ecosystem Restoration NFIP National Flood Insurance Program NGO non-governmental organization NISP Northern Integrated Supply Project NOAA National Oceanic and Atmospheric Administration NRCS Natural Resources Conservation Service NRHP National Register of Historic Places OHWM ordinary high water mark OMRR&R operation, maintenance, repair, replacement and rehabilitation OSE other social effects PED pre-construction engineering and design PGN Planning Guidance Notebook PPA Project Partnership Agreement RED Regional Economic Development SFHA Special Flood Hazard Area SHPO State Historic Preservation Office TSP tentatively selected plan UDV unit day value USACE U.S. Army Corps of Engineers USDA U.S. Department of Agriculture USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey VE value engineering WRDA Water Resources Development Act
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CACHE LA POUDRE RIVER AT GREELEY, COLORADO DRAFT FEASIBILITY REPORT AND ENVIRONMENTAL ASSESSMENT
1. STUDY AUTHORITY
The Cache la Poudre River in Greeley, Colorado Study is being carried out under the U.S. Army Corps of Engineers’ (USACE) General Investigation (GI) Program. This study is authorized under a resolution dated March 22, 1971, by the Committee on Public Works of the United States Senate referencing Section 3 of the River and Harbor Act of June 1902:
“RESOLVED BY THE COMMITTEE ON PUBLIC WORKS OF THE UNITED STATES SENATE, That the Board of Engineers for Rivers and Harbors, created under the provisions of Section 3 of the River and Harbor Act approved June 13, 1902, be, and is hereby requested to review the report of the Chief of Engineers on the South Platte River and Tributaries, Colorado, Wyoming, and Nebraska, published as House Document Numbered 669, Eightieth Congress, and other pertinent reports, with a view to determining whether any modifications of the recommendations contained therein are advisable at this time, with particular reference to the desirability of developing a comprehensive plan for the utilization and conservation of water and related land resources of the South Platte River Basin, in the interest of flood control, regional water supply and waste management, water quality control, recreation, fish and wildlife conservation, wise use of floodplain, lands, and other resources for enhancement and protection of the environment. Investigation to be coordinated with the State of Colorado, local governmental entities, and other interested Federal and State agencies.”
2. STUDY PURPOSE AND SCOPE
This study addresses three of the purposes called for in the resolution: flood risk management (FRM), ecosystem restoration (ER), and recreation. This is an interim response to the study authority.
This report contains an environmental assessment (EA) and biological assessment integrated within the text of this report. Table 1 shows typical EA headings and the report sections where these EA subjects are found. A Finding of No Significant Impact (FONSI), 404(b)(1) evaluation, and coordination correspondence are in Appendix E.
Cache La Poudre River at Greeley, Colorado 1 Draft Feasibility Report and EA April 11, 2014
Table 1. EA headings and corresponding report sections
EA Heading Report Sections
Purpose of and need for Section 4.0 – Problems and Opportunities action Section 6.0 – Existing and Future-Without Project Conditions
Affected environment Section 6.0 – Existing and Future-Without Project Conditions
Alternatives Sections 8.45-8.47 – FRM Nonstructural Alternatives Section 9.4 – ER Alternative Site Plans Section 9.5 – ER Alternative Evaluations and Comparisons Section 10.2 – Recreation Opportunities and Measures Section 10.3 – Recreation Plan Development and Evaluation
Environmental consequences Section 9.5 – ER Alternative Evaluations and Comparisons Section 11.7 – Summary of Environmental and Social Effects (Environmental Effects)
3. LOCATION AND SPONSORSHIP
Greeley is located on the high plains of northern Colorado, approximately 15 miles east of the Front Range and 55 miles northeast of Denver (Figure 1). The Cache la Poudre River originates in the Rocky Mountains, flows across the plains and passes along the north side of Greeley, before merging into the South Platte River just east of Greeley. The study reach is the 17 downstream miles of the Cache la Poudre River, from the confluence with the South Platte to just west of Greeley (Figure 2). The proposed ecosystem restoration project spans the middle eight miles of the study reach. The proposed flood risk management reach spans approximately a nine-mile reach. Recreation features were also evaluated. The study area is located in Congressional District 4.
The city of Greeley, Colorado is the non-federal sponsor for this study, has provided cash and work in-kind contributions toward its share, and intends to act as implementation sponsor for a project approved through this study. A 1999 flood provided impetus to begin the current study. A Planning Assistance to States report which addressed floodplain management issues was prepared for the city in 2002. A 905(b) reconnaissance report was completed in 2004 and approved by the Northwestern Division in September 2005. A Feasibility Cost Share Agreement for this study was signed between Greeley and the U.S. Army Corps of Engineers (Corps) in December 2005.
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Figure 1. Project location map
Cache La Poudre River at Greeley, Colorado 3 Draft Feasibility Report and EA April 11, 2014
Figure 2. Cache la Poudre River study area
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4. PROBLEMS AND OPPORTUNITIES (PURPOSE OF AND NEED FOR ACTION)
The primary flood risk management problem in and near Greeley is that hundreds of residential and nonresidential structures and infrastructure are vulnerable to damage from recurring flooding of the Cache la Poudre River, and flooding is expected to increase in both frequency and severity in the future. The purpose of a Corps flood risk management project would be to reduce flood damages and risks in a cost-effective manner that would contribute to the national interest.
Human settlement and economic activity since the mid-1800s has significantly altered the hydrology, channel form, and floodplain habitats of the Cache la Poudre River in the vicinity of Greeley. The primary ecosystem problems along the Cache la Poudre River near Greeley are the loss and degradation of wetlands and of riverine habitat diminishing habitat for migratory birds and other native species. These problems are expected to persist and increase due to population growth and commercial development in the future. The purpose of a Corps ecosystem restoration project would be to find the most cost-efficient opportunities to restore those lost habitat values that are of federal interest.
The recreation problem associated with the Cache la Poudre River at Greeley is the shortage of access to provide the public with environmental experiences and education, based on substantial public interest. The purpose of a Corps recreation project would be to take advantage of any Corps ecosystem restoration work by adding environmentally benign access opportunities for the public.
5. PRIOR STUDIES, REPORTS, AND EXISTING PROJECTS
The following prior studies and reports have been relevant in the current study.
Flood Insurance Study, City of Greeley, Colorado, U.S. Department of Housing and Urban Development, Federal Insurance Administration, January 1979. The study provided flood profiles and other information for the National Flood Insurance Program (NFIP). A flood boundary, floodway map and Flood Insurance Rate Map (FIRM) were published.
Section 205 Reconnaissance Report, Cache la Poudre River, Greeley, Colorado, Omaha District, Corps of Engineers, 1981. The study focused on the reach between Island Grove Park and Ash Avenue. Alternatives included nonstructural measures, bridge enlargement, upstream dams, channel improvement, levees, and diversion. Buyout was found to be economically infeasible. Flood proofing was not studied in detail because the city preferred structural solutions. The study concluded there may be federal interest in levees or a combination of levees and channel improvements. The city chose not to pursue this type of project with levees close to the riverbanks, feeling it would not provide opportunities for environmental improvement, recreation, and community enhancement.
Master Floodway Plan – Cache la Poudre River, Simons, Li, and Associates, Inc. August 1983. This Master Floodway Plan was to develop and evaluate alternatives to reduce flood damages. Detailed hydraulic analysis of several alternatives was performed as well as verification of the
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1979 Flood Insurance Study (FIS) results. A preliminary design was developed for the recommended alternative. The plan as adopted by the city in 1983 called for replacement or enlargement of the 8th Street, 5th Street, and 6th Avenue bridges; also relocation of a diversion structure; and a combination of channel improvements and levee construction. The recommended plan was to provide 1 percent annual chance of exceedance (ACE) (100-year) flood protection for the Cache la Poudre River through Greeley.
Final Design Report, Master Floodway Plan for the Greeley Reach, Cache la Poudre River, Greeley, Colorado, Warzyn Engineering Inc., May 1986. This report was to develop designs for channel improvements, levees, and bridges, to reduce damages from floods. Omaha District used the Warzyn design analysis in the 905(b) study that preceded the current study. The city implemented several bridge modifications recommended in the report; however, channel improvements and levee modifications were not initiated.
Cache la Poudre River Trail Master Plan, City of Greeley, Weld County, and Town of Windsor, April 1995. Cache la Poudre Trail Master Plan objectives included promoting the river corridor as a recreational resource, as an educational resource, and as a transportation route; and to protect and enhance its natural systems. It addressed specific trail features.
In 1998, Greeley began an effort to retain areas with natural ecosystems for Greeley and its surrounding Weld County growth area. Through an Open Space Advisory Committee, Greeley produced the Greeley Open Space System Plan and Implementation Program. This set out objectives to restore many of the riverine and riparian resources: the river/floodplain connection, wetland habitat, riparian habitat, habitat for federally-listed threatened and endangered species, National Heritage Program species, state species of concern, migratory bird habitat, and a connective corridor between the South Platte River and the Front Range. It also sought related ecosystem education opportunities.
After the major flood of 1999, the city proposed the Cache la Poudre Floodway Improvement Program. Its goals included:
Reduce the potential for flood damage, injuries, and deaths, by constructing channel improvements, acquiring floodway areas, and creating overbank open space. Incorporate facilities to safely pass the 1 percent ACE (100-year) stormwater flows from various city drainage basins into the river. Remove commercial/industrial developments from floodway or floodplain areas. Change boundaries of the floodplain to coincide with a future, planned Cache la Poudre River corridor that allows for less restricted development on 775 acres of the current 851 acres of floodplain from the river’s confluence to 83rd Avenue. Provide recreation opportunities along the new channel, including connection with a regional trail system and possible National Park designation by way of the River Heritage Corridor. Restore the riparian and stream corridor, and improve water quality.
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Section 22 Planning Assistance to States Study – Floodplain Land Use Data Collection Study, Cache la Poudre River, Greeley, Colorado, U.S. Army Corps of Engineers, May 22, 2002. The Corps evaluated land use in the floodplain area inundated at the 0.2 percent ACE (500-year) level plus two feet, from the mouth of the Cache la Poudre River to approximately 20 miles upstream. The study determined types of structures, first floor elevations, approximate market values, location, and depth of flooding at various events. The information was used in the current study’s economics and plan formulation.
Section 905 (b) Reconnaissance Study Preliminary Analysis Cache la Poudre River – Greeley, Colorado Flood Damage Reduction and Environmental Restoration Study, U.S. Army Corps of Engineers, April 2004. The reconnaissance study used existing data to determine the likelihood of federal interest, following the replacement of constrictive bridges and the 2002 Floodplain Land Use Study. It was determined that a feasible project was likely.
Existing flood risk management projects The Cache la Poudre River has been utilized for water in this semi-arid region since the 1800s. However, there are no significant flood reduction projects. While there are many small non- engineered spoil bank levees in the floodplain in Greeley, none are sufficiently high or long enough to offer protection from large floods, and they have considerable risk of failure in a major event. There are many low head diversion dams upstream and in Greeley, but no dams that could capture major floods. Dams on mountain tributaries offer limited capture of spring snowmelt.
6. EXISTING AND FUTURE WITHOUT-PROJECT CONDITIONS (PURPOSE OF AND NEED FOR ACTION, AFFECTED ENVIRONMENT)
6.1 History of Flooding
Flooding from the Cache la Poudre River has posed a significant threat to Greeley since settlement in the mid 19th Century. Rapid mountain snowmelt and slow moving thunderstorms in the Foothills canyons and on the high plains are capable of producing tremendous volumes of runoff that can flood the lowlands. Efforts to obtain relief from flooding began after the floods of 1965 devastated many communities along and east of the Rocky Mountains’ Front Range. Major flooding occurred in 1983, and minor flood events occurred in 1994 and 1997. The flood in May 1999 caused nearly $3,500,000 of direct flood damages and cleanup expenses, in fiscal year (FY) 2014 prices. Floods in 2013 had minor impacts in Greeley but major impacts on neighboring communities, illustrating the potential of the region’s basins to experience major events.
1863 A flood on June 6, 1863 destroyed a camp of the 1st Colorado Calvary.
1904 In May, a combination of snowmelt and heavy rains in the mountains led to the Cache la Poudre River flooding 1.5 miles wide downstream of Boxelder Creek. Every bridge between Fort Collins and Greeley was washed out. One person was killed upstream of Greeley. Flows
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washed out a bridge and a portion of the railroad tracks. Extensive crop damages were also reported. Damages were estimated at approximately $26 to $77 million in FY 2014 dollars. Estimates for discharge range as high as 18,000 cubic feet per second (cfs) at the Greeley gage.
1917 The flood of June 1917 was caused by rain falling on melting heavy snow pack in the higher mountains. Low elevation rain supplemented the flood. The flood peak was estimated to be 4,240 cfs at the Greeley gage.
1923 A very wet June followed a snow season that produced snow cover about 50 percent greater than normal. Extensive flooding occurred on the Cache la Poudre River around Greeley and closed highways north and west of Greeley. Discharge estimates are not available.
1947 A combination of heavy rains on the plains (2.7 inches in 1.5 hours at Windsor), and melting mountain snowpack, caused extensive flooding in and around Greeley in June. A spoil bank dike broke on north 9th Avenue, and the adjacent residential area was flooded. Over 200 inhabitants of 100 homes were ultimately evacuated. The peak discharge was 4,050 cfs.
1951 Heavy rains over the foothills caused flooding on the Cache la Poudre River upstream of Greeley in Fort Collins, and minor lowland flooding downstream of there. Although nearly 12 inches of rain fell near Bellvue, Colorado, the flood attenuated significantly as it moved downstream and no damages were reported in Greeley. Peak discharge was 3,760 cfs on August 5th.
1965 Early June rains saturated a wide area of eastern Colorado. Flooding was severe along the Front Range; however, the flood attenuated somewhat by the time it reached the mouth of the Cache la Poudre River. The peak discharge at Greeley was 3,480 cfs. Within Weld County, 12 people died (not in Greeley), and estimated damages were over $750 million in FY 2014 dollars. The flooding in the Greeley area was worse in rural areas than in the city. In Greeley, floodwaters closed the 6th Avenue and 5th Street bridges and overflowed in the rural lowlands to the north and east of the river.
1983 Heavy spring snows and an early thaw led to very high rivers and streams throughout Weld County. This flood peaked at 6,360 cfs June 14th during a long period of high flows. The peak discharge had an expected return interval of between 25 and 50 years and did extensive damage in Greeley.
1999 In late April and early May of 1999, rainfall on the basin combined with melting mountain snowpack to cause extensive flooding in Greeley. The flood peaked at 4,930 cfs, resulting in an event with just above a 20-year return interval. Much of the floodplain within Greeley was flooded and the Highway 85 Expressway was overtopped. The flood caused nearly $3.5 million
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in damages and clean-up expenses (FY 2014 dollars). Weld County was declared a federal disaster area. The city applied for and received assistance from the Federal Emergency Management Agency (FEMA) after the flood. This flood became the impetus for this GI study.
2013 In September 2013, heavy rain caused catastrophic flooding along Colorado’s Front Range. Boulder County upstream received nine inches of rain September 12th; up to 17 inches were recorded by September 15th. Overflow of the South Platte River caused flooding in Weld County affecting 3,000 homes and over 350 commercial properties. One hundred twenty-two (122) bridges were damaged, and 654 lane-miles of road in Weld County were damaged or inundated. Portions of Greeley were under mandatory evacuation, and neighborhoods in Greeley and nearby Evans were submerged. This flooding was not from the Cache la Poudre River basin but does illustrate flood risks from rainfall alone in the area.
6.2 Hydrologic Conditions
The Cache la Poudre River is a tributary of the South Platte River, and it drains approximately 1,890 square miles (Figure 3). Its headwaters are located in the Rocky Mountains approximately 45 miles upstream from Greeley, with peak elevations around 13,600 feet above mean sea level (msl). It drops in elevation to 4,600 feet msl near Greeley. The mountainous headwaters are subject to heavy snows which contribute large volumes of mountain runoff in spring. Downstream from the Rockies, the river transitions into semi-arid plains which receive average annual rainfall of 12 inches. Headwater snowmelt occurs April through early July, and plains thunderstorms occur May through September. Consequently, the greatest runoff volume floods have occurred in May and June when thunderstorm events coincide with peak snowmelt runoff.
River flow discharge information was gathered for hydrologic model development, calibration, verification, and statistical analyses. Hydrologic data were obtained from the U.S. Geological Survey (USGS) Water Resources computer database. Data on the USGS streamflow gages, their locations, gage identification numbers, and periods of record are shown in Table 2.
Table 2. Cache la Poudre River basin gaging station data Stream and Location Station ID Gage Type Contributing Period Drainage Area of Record (sq mi) Cache la Poudre River at 06752000 Flow 1,056 1883-2004 mouth of canyon, near Fort Collins, CO Cache la Poudre River 06713500 Flow 1,877 1914-1919 near Greeley, CO 1924-2005
Meteorological records were also gathered for hydrologic modeling and trend analysis. Precipitation data were obtained from the National Oceanic and Atmospheric Administration (NOAA). Climatological data for nearby gages and are listed in Table 3.
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Table 3. Data from climatological gaging station Gage and Location NOAA Index County Gage Type Period of Number Record Greeley, CO 3546 Weld Precipitation 1915-67 Greeley UNC, CO 3553 1968-04 Fort Collins, CO 8932 Larimer Precipitation 1948-02
CACHE LA POUDRE RIVER BASIN
COLORADO Wyoming Weld County Colorado Larimer County
rk C th Fo a Nor c he
la P o ud re
Cache la Poudre River
Fort Collins
C ac he la Poudre
Greeley tte Riv N la er P th ou S
Larimer County W E Boulder County S 10 0 10 20 Miles
Figure 3. Cache la Poudre River basin
Trend Analysis Analysis of the two long established river gages indicated a trend of increasing plains runoff and discharge for the more frequent flood events. The upstream Fort Collins gage did not show a trend of change in mountain runoff, and showed no change in extreme events which are dominated by the mountains’ runoff. The Greeley gage, however, showed a marked increase in runoff over the last 30 years. This period of increase reflects rapid urbanization between Fort Collins and Greeley (Figure 4). Urbanization includes streets, driveways, and rooftops, which reduce precipitation infiltration and increase runoff into the river. Because urbanization will likely maintain and increase over the 50-year study period, it was projected that the shift to higher peaks for more frequent events will maintain or increase in the study period.
Cache La Poudre River at Greeley, Colorado 10 Draft Feasibility Report and EA April 11, 2014
Cache la Poudre River nr Greeley, Co Annual 1-, and 7-Day Maximum Flow 7000
Legend 6000 1-Day Maximum Flow 7-Day Maximum Flow 5 Yr Moving Ave (1-Day) 5 Yr Moving Ave (7-Day) 5000
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Figure 4. 90-year history of annual peak runoff volumes
Future peak discharges were forecast for the 30-year period 2005-2035, based upon trends during the preceding 30-year period. A summary of existing and projected future discharges for various flood events is provided in Table 4.
Table 4. Comparison of existing and future (2035) conditions’ peak discharges (cfs) Cache la Poudre 100- 2-Year 5-Year 10-Year 25-Year 50-Year 500-Year River at Greeley Year Existing 1,500 2,490 3,520 5,410 7,420 10,100 20,300 Future (2035) 2,050 3,230 4,140 5,580 7,420 10,100 20,300 (+37%) (+29.7%) (+17.6%) (+3.1%) (0.0%) (0.0%) (0.0%) Note: Bottom value is the percent change from the existing condition.
Volume Probability Flooding of the Cache la Poudre River is characterized by long duration peaks from snowmelt originating in the distant mountains. Volume and duration distribution was analyzed, using the maximum flow over several durations for each year of available records, to derive inflow volumes for various events. The volume probability relationship is shown in Figure 5 and Table 5.
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Cache La Poudre River nr Greeley, Colorado Flow and Volume Probability Relationships Existing and Future Conditions 100000
Durations
Adopted Flow Probability )
s Future Conditions (2035)
f c
( Existing Volume Probability
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1000 0.9999 0.999 0.99 0.95 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.05 0.01 0.001 0.0001 Chance of Exceedance Note: Flow probabilities developed from regression equations. Computed probabilities shown. Figure 5. Flow and volume probability relationships – existing and future conditions
Table 5. Volume probability – Bluff Line gage near Fort Collins and at Greeley Volume Probabilities (cfs) Gage 2-Year 5-Year 10-Year 20-Year 50-Year 100-Year 500-Year Bluff Line Gage near Fort Collins 1-Day 2470 3550 4360 5220 6440 7450 10200 3-Day 2340 3340 4060 4780 5780 6570 8590 7-Day 2170 3070 3670 4260 5040 5640 7070 15-Day 1970 2770 3320 3850 4550 5090 6370 30-Day 1700 2390 2860 3310 3910 4370 5470 60-Day 1340 1870 2230 2580 3040 3400 4240 At Greeley Gage 1-Day 1810 3020 3920 4880 6250 7380 10500 3-Day 1680 2880 3750 4620 5820 6770 9210 7-Day 1500 2570 3290 4000 4930 5650 7360 15-Day 1280 2270 2950 3610 4470 5140 6720 30-Day 960 1740 2280 2790 3480 4000 5250 60-Day 660 1230 1610 1980 2460 2840 3730
Future Basin Developments Projects under consideration by others would withdraw or store flows for municipal water supply and irrigation. Chief among these is the Northern Integrated Supply Project (NISP) and the accompanying reservoirs, which would intercept snowmelt near the mouth of the Poudre Canyon. Typical NISP diversions from the Cache la Poudre River would be in the range of 800 to 1,200 cfs. Such diversions by others cannot be predicted adequately to forecast their effect on Greeley flooding, nor relied on to provide flood relief in Greeley.
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Climate Change It is infeasible to quantitatively estimate the potential impact of future climate change on rainfall- runoff patterns in the Cache la Poudre River basin. In turn, complex basin geography makes it impractical to forecast how impacts to the upper basin will be felt in the lower basin. Regional projections of a warmer climate would have a tendency to initiate high mountain snowmelt earlier and spread the melt over a longer duration which in turn would lower peak discharges for the more infrequent snowmelt events. Increased frequency of flooding from precipitation events over the urbanized plains area would still occur due to the increased urbanization. Because of the uncertainty of future climate changes no adjustments to the future conditions’ flood frequency were made to account for future climate change.
6.3 Hydraulic Conditions
The Cache la Poudre River corridor has broad, gentle topography that averages less than 1 percent slope from the Weld-Larimer County line to Greeley. This flat topography subjects the bottomlands to widespread flooding. The floodplain has many gravel quarries; however, these naturally recharge with groundwater unless they are lined, and therefore provide minimal flood storage.
Hydraulic analysis was performed using the Hydrologic Engineering Center-River Analysis System (HEC-RAS) version 4.1 Beta computer model. Three hydraulic models used in the 2003 FIS were updated and combined into one model, to compute water surface profiles from the mouth of the Cache la Poudre River, to approximately 20 miles upstream to Weld County Road 23.
Channel Aggradation Channel sediment deposition (aggradation) has occurred over time; channel margins are encroaching and channel bars have formed. The deposits are being colonized by vegetation, which can remain until it is scoured away by high flows. Based on historical observations, aggradation is expected to continue into the future, leading to reduced channel conveyance, higher stages, and more damages for a given future flood discharge. Annual deposition rates can vary. However, based on historical trends indicating deposition of material in the Greeley reach, one foot of aggradation within the channel (not overbanks) was assumed for future conditions. The continued aggradation of the channel will have limited effect on the larger floods.
The effects of changes in hydrology and aggradation on future flood profiles are shown in Table 6. The average difference in water surface between existing conditions and future without project conditions is 1.7 feet for the 50 percent ACE event, 1.2 feet for the 10 percent ACE event, 0.4 feet for the 2 percent ACE event, 0.2 foot for the 1 percent ACE event, and 0.1 foot for the 0.2 percent ACE event for the high damage reach.
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Table 6. Existing and future-without project water surface elevations (ft) Annual Exceedance 0.50 0.20 0.10 0.05 0.04 0.02 0.01 0.002 Probability & 2-yr 5-yr 10-yr 20-yr 25-yr 50-yr 100-yr 500-yr Recurrence Interval Discharge in cfs: Current Conditions 1500 2490 3520 4880 5410 7420 10100 20300 (Future Conditions) (2050) (3230) (4140) (5180) (5580) (7420) (10100) (20300) Average difference, 1.3 1.2 0.9 0.6 0.5 0.3 0.2 0.2 entire main channel1 Average difference, 1.7 1.5 1.2 0.7 0.6 0.4 0.2 0.1 high damage reach1 Average difference, entire main channel 0.6 0.5 0.4 0.2 0.1 0.0 0.0 0.0 DISCHARGES ONLY1 Average difference, high damage reach 0.9 0.7 0.5 0.3 0.2 0.0 0.0 0.0 DISCHARGES ONLY1 Average difference, N/A N/A N/A N/A 1.9 1.0 0.6 0.6 right split reach2 Average difference, N/A N/A 0.7 0.9 0.6 0.3 0.2 0.1 left split reach2 1 Positive value indicates future without project conditions water surface is higher than existing conditions 2 No aggradation
Future Hydraulic Conditions The computed water surface profiles indicated that hydraulic control during flood events is often at road embankments and bridge openings. Undersized bridge openings and elevated road and railroad embankments can restrict flows through the bridge resulting in increased flood profiles. Other encroachments on the channel in the form of spoil bank levees and channel stabilization through riprap or concrete rubble could further reduce conveyance capacity and contribute to increased flood stages in the future. The net impact of current trends in the channel and floodplain is that Greeley could experience higher flood stages and consequently greater flood risk and damage potential.
6.4 Floodplain Management
Greeley participates in the NFIP, has local floodplain management regulations that meet the minimum standards of the NFIP, and will continue to enforce those. State regulations are stricter than the NFIP minimum standards, i.e., they require that new construction or substantial modifications be elevated to one foot above the 1 percent (100-year) annual probability flood elevation, rather than only to the flood elevation.
FEMA has published official floodplain maps for Greeley and Weld County. The current effective floodplain maps for Greeley date to July 1979 and those for Weld County date to March 1980. Updated floodplain mapping was finalized in 2006, and the hydraulic models developed for that study were the basis for those used in this feasibility study. The updated flood profiles, flood boundaries and floodway have been adopted by Greeley for floodplain management purposes. These data will also be incorporated into revised FIRMs for Greeley and
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Weld County when FEMA completes the pending mapping update for Weld County. FEMA has initiated a study to develop a Digital Flood Insurance Rate Map (DFIRM) for Weld County, including Greeley. The DFIRM will include floodplain and floodway boundaries and base flood elevations. The results from the Corps’ 2003 floodplain study for the Cache la Poudre River (as revised in 2006) will be incorporated into the DFIRM.
With or without a project, enforcement of the floodplain regulations will ensure future development is in compliance with local, state and federal floodplain management regulations. In the event of a flood, NFIP regulations require buildings that are “substantially damaged,” with repair costs greater than 50 percent of market value, be brought into compliance with current NFIP standards. For residential buildings constructed before Greeley enacted the NFIP’s floodplain management regulations, this would require that the residences be elevated one foot above the base flood elevation or be removed from the 1 percent (100-year) annual chance floodplain.
Flood insurance policies now include coverage to help pay for the “increased cost of compliance” to bring substantially flood-damaged buildings up to current standards when repairs are made following flood damage. In the event that flooding results in a declared federal disaster, a portion of the total federal disaster assistance is allocated for hazard mitigation projects, such as buyouts of flood-prone buildings. The effect of these programs could incur a higher cost to the nation than a flood risk reduction project, but could also gradually reduce the number of buildings in the floodplain or reduce the potential future flood damages.
Potential future changes in hydrology and hydraulics are not likely to result in significant changes to the 1 percent (100-year) ACE floodplain as it is currently delineated at Greeley.
6.5 Geotechnical and Soil Conditions
Geotechnical analysis was based on available sampling records and documentation. Channel width varies significantly within the study reach. Bank slopes also vary but are often steep, from vertical to an approximately 1V on 3H slope (18° slope) at the upper reaches of the channel bank. The upper channel slopes are predominately about 1V on 2H slopes (26° slope).
Material has been dumped, or berms have been constructed, at the top of the banks in several areas. None of these were constructed to a levee design standard, and none are certified as an “engineered structure.” Their composition appears diverse. At numerous locations, trees, shrubs, rock, rubble, and asphalt are on the berms; debris and rubble may also be inside the berms. In general, the berms are in poor condition, are not aligned well to protect areas from flooding, are privately owned, and are not regulated. It is assumed that in future conditions, these could be compromised by alteration or removal of material, will lack sufficient structural integrity, will experience slope failure, seepage, toppling of trees, or flanking, and will fail during major floods due to these geotechnical deficiencies.
A desktop review of geology and soils was conducted of the project area and adjacent landscape. A majority of the underlying geology in the project area consists of White River Formation or Group and Eolian deposits. White River Formation or Group is an ashy claystone and sandstone which includes Castle Rock Conglomerate sub-groups. Eolian deposits consist of dune sand, silt
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and Peoria Loess (USGS, 2014). Of particular interest is the Niobrara play, which oil and gas prospectors are currently developing. The shale play is about 275 to 400 feet deep, with three primary carbonate-rich benches that average 10 to 25 feet in thickness (COGA, 2014). Project area soil is dominated by Aquolls, Aquents, and gravelly substratum; parent material is mostly recently deposited alluvium.
6.6 Fisheries
The Colorado Parks and Wildlife (CPW) maintains nine sampling sites within the study area and another just upstream of the study area. Some sampling records date as early as 1912 but most date from 1984 and later. CPW records indicate that fish species diversity has declined over time. From 1982-1994, 29 species of fish were documented within and just beyond the study area. Between 2001 and 2004, 20 species were recorded in the study area (Vermillion, 2008). The species are best described as Eastern Plains, warm-water transitional species and include a large number of non-native introductions, such as common carp which has remained very common (Davies, 2008). Common native species include the bigmouth shiner, fathead minnow, green sunfish, Johnny darter, red shiner, sand shiner, and white sucker (Vermillion, 2008). Of the native species captured during sampling, three are state listed as threatened, endangered, or of special concern: northern redbelly dace, brassy minnow, and Iowa darter (CPW, 2007).
Fish that are very uncommon in the area (last observed date in parentheses) are brassy minnow (1988), brown trout (1983), common shiner (1983), goldfish (1914), Iowa darter (1994), northern redbelly dace (1914), mountain whitefish (1983), plains killfish (1994), plains topminnow (2001), rainbow trout (1993), river carpsucker (1914), small mouth bass (1973), and yellow perch (2001) (Vermillion, 2008). Loss of native species and decreased species diversity may be due to increases in water temperature, degradation of water quality, altered flow regimes, loss of spawning habitat and presence of migration barriers (Davies, 2008).
6.7 Riparian Habitat
This area provides migration habitat for waterfowl, shorebirds, and neotropical migratory songbirds. Avian species common to this habitat include the American kestrel, mourning dove, northern flicker, western wood-pewee, western kingbird, house wren, black-billed magpie, American robin, yellow warbler, blue grosbeak, and Bullock’s oriole (CPF, 2000). Raptors include bald eagle; hawks include eastern and western red-tailed, Swainson’s, Cooper’s, sharp- shinned, and rough-legged (Wheeler, 2003). Habitat for international migratory birds has been degraded as result of diversions, flood control, agriculture, and human activity. Much of the river in the study reach has been straightened, and the meanders and oxbows have been filled in. Riparian habitat features that birds need (i.e., tree canopy cover, shrub density, cover near water) are greatly diminished. A reported 70 percent of riparian forests have been lost since settlement. Remaining riparian habitat is fragmented and low quality. In the future, habitat is likely to decline further with gravel mining and development.
Two riparian forest types are present in the study area; plains cottonwood riparian forest and exotic riparian forest. Plains cottonwood riparian forest is dominated by plains cottonwood, peachleaf willow, and mostly non-native grasses and forbs. The exotic riparian forests are dominated by Siberian elm, Russian olive, and contain mostly non-native understories of grasses
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and forbs such as leafy spurge, black willow, Canada thistle, sweet clover, dock, and Asian reed canary grass. Plains cottonwood riparian forest is a unique and valuable habitat within the study area due to its relatively high productivity, proximity to water, multi-story structure, and sometimes dense cover. Without natural resource restoration and protection efforts, native plant and animal life will continue to decline and invasive species, including tamarisk, reed canary grass and Russian olive, will continue to advance.
Mining of sand and gravel has consumed large areas of the meander belt, and this trend continues. Excavated gravel mines are often left deep and are sealed from groundwater recharge by impermeable slurry walls constructed to bedrock, or by liners of bentonite, to store water, providing little habitat. Hundreds of ponds along the river are hydrologically connected to the river through the groundwater table; during hot and dry summers, their high evaporation rates can draw groundwater away from the river. It is not possible to accurately predict the specific location of gravel mines; however, it is likely that gravel mining will continue and that many gravel mines will be converted to water storage lakes.
Significance Migratory bird habitat is institutionally significant and is in the federal interest because of the Migratory Bird Treaty Act (16 USC 703-712). The act provides protection to migratory birds and prohibits the destruction of their active nests or nestlings. For this study, migratory bird habitat is equated to riparian forested and scrub-shrub habitat. Riparian habitat is riverside vegetation that interacts with surface water and groundwater connected to the river.
The U.S. Fish and Wildlife Services’ (USFWS) Mountain-Prairie region ranks riparian habitats, especially cottonwood-willow associations, as a critical wildlife resource (USFWS, 2001). The reach of the Cache La Poudre River through Greeley has also been designated as critical wildlife habitat by CPW. Lowland riparian systems, such as the plains cottonwood riparian forest, have the richest avian species component of any of Colorado’s habitats (CPF, 2000), and provide the most important wildlife habitat in Colorado in terms of species diversity and abundance. Riparian habitat is regionally scarce and becoming scarcer, based on USGS Circular 1284 (Murphy, 2006). Riparian areas account for only three percent of Colorado’s land area according to USFWS, or less than one percent according to CPW; yet they form essential habitat for over 50 percent of Colorado’s bird species. Of the bird species using the area, 59 percent use the river year-round. The remaining 41 percent are neotropical species and other migrants that use the river and sloughs as migration corridors and stopovers, dispersal corridors for woodland birds across the otherwise treeless terrain (CPF, 2000).
The USFWS stated that habitat restoration targeting aquatic, wetland, and riparian habitats would be consistent with goals of the U.S. Shorebird Conservation Plan, the North American Waterbird Conservation Plan, and the North American Waterfowl Management Plan. These plans are adopted by state and federal agencies and non-governmental organizations across the country to determine species, sites, and habitats that most urgently need conservation and/or restoration, making them institutionally significant for restoration plans within the study area.
The CPW states that Weld County is one of the most important waterfowl regions in the U.S. (2012). The CPW’s Natural Diversity Information Source reports 297 avian species are known
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or likely to occur within the county. Of those, the Colorado Breeding Bird Atlas II lists 86 species probable or confirmed in the study area (Wickersham, 2008). Several species listed as Birds of Conservation Concern (USFWS), state species of concern, natural heritage elements, and priority species for conservation programs nest and feed in the riparian portion of this study area, as detailed in Section 6.11. With the restoration of suitable migratory bird habitat, more of the species present in Weld County but absent from the study area might return there to reproduce, rear their young, forage, and find shelter.
Healthy riparian areas also perform several other important ecosystem functions beyond serving as migratory bird habitat. Riverine corridors often serve other wildlife as critical connection and dispersal corridors. Approximately 35 percent of non-avian wildlife species in Colorado are dependent on riparian areas during all or a portion of their life cycle. Riparian vegetation can also shade adjacent waters, contribute structure to aquatic habitat by fallen trunks and limbs, and contribute organics to aquatic habitat through fallen leaf litter.
Public significance is indicated by local recognition of the values of the riparian community. Greeley, through the Open Space Advisory Committee, identified the Cache la Poudre River and South Platte River floodplains as the largest concentration of highest priority lands for open space. These lands form a band ranging in width of 1,500 feet to 3,000 feet along the two rivers.
Additional public significance was demonstrated by the American Rivers’ 2008 designation of the Cache la Poudre River as one of the “Most Endangered Rivers in America.” This designation was based on three criteria: (1) threat level, (2) a major decision pending regarding the river, and (3) its regional and national significance.
6.8 Vegetation
Six separate field surveys were conducted between May and October, 2009 to identify common plant species and plant communities within the study area. Appendix E provides a complete list of 240 plant species including those not observed but still expected within the study area. Of the 49 new species, a majority are ruderal weedy species preferring disturbed or waste areas. Table 7 lists the plant communities inventoried at the study area.
Table 7. Inventoried plant communities Plant Community Acres Cattail-Rush-Sedge Wetland 125 Reed Canary grass Wetland 39 Shrub Riparian Wetland 29 Riparian Forest 292 Exotic Riparian Forest 15 Grass/Forb Mixed Rangeland 300 Ruderal Rangeland 1,630 Agricultural 2,202
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Appendix E also lists plant species considered to be noxious weeds by Weld County. Eight of these species, and other notable weeds not on Weld County’s list, were observed in the field.
Neither of the federally-listed species, the Colorado butterfly plant or the Ute ladies’-tresses orchid, were observed during field surveys.
6.9 Wetlands
Wetlands are important features of this riparian system along the Cache la Poudre River, and are of federal interest and institutionally significant due to the Clean Water Act (CWA) and Executive Order (EO) 11990. Wetlands occur in areas where soils are saturated or inundated long enough during the growing season to support a prevalence of hydrophytic vegetation (i.e., plant species that grow in water or on a substrate that is at least periodically deficient in oxygen because of excessive water content). In the riparian area of the project boundary, two major types of wetlands occur: palustrine shrub-scrub, and palustrine emergent.
One type of palustrine emergent wetland is a vegetation community dominated by cattails, rushes, and sedges, with a lesser component of reed canary grass and a variety of other perennials and herbs adapted to saturated soils. Many of these wetland sites are located within abandoned oxbows in the floodplain adjoining the river. They are also found in depressions or swales on uplands within the study area. See Figure 6 for a typical view of these areas.
Figure 6. Palustrine emergent wetland dominated by cattails, rushes and sedges
Another emergent wetland community is the type dominated by reed canary grass, which occupies sediment deposits below the ordinary high water mark (OHWM) of the river. Reed canary grass is very effective at outcompeting all other herbs and grasses on sand and gravel bars within the river’s OHWM and is often the only species in this community. Narrow-leaf willow may provide up to 25 percent cover in these wetlands. See Figure 7 for a typical view of these areas.
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Figure 7. Wetland dominated by reed canary grass
Palustrine shrub-scrub wetlands are plant communities characterized by riparian shrub cover equal to or great than 25 percent. The dominant plant association is narrow-leaf willow and reed canary grass. These shrub-scrub wetlands are normally below the river’s OHWM. See Figure 8 for a typical view of these wetlands.
Figure 8. Palustrine shrub-scrub wetlands
6.10 Wildlife
Appendix E provides a list of birds, fish, mammals, reptiles and amphibians expected to occur in the study area, and the species observed during 2009 field surveys.
6.11 Federally and State-Listed Species
6.11.1 Federally Listed Several federally-listed threatened or endangered plants and animals historically occurred within the project area, and some are still found within Weld County or nearby counties. While most of
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the species have not been seen in the study area in recent years, individuals or seeds could potentially reenter the area in the future.
Colorado Butterfly Plant The Colorado butterfly plant is federally listed as threatened. This plant is normally found in moist areas of floodplains. One population has been identified in Weld County. Habitat in Weld County, Colorado was excluded from “Critical Habitat” designation in 2004 because the city of Fort Collins signed a conservation agreement with the USFWS. The species is not known to occur in the project area; however, seeds could recruit to the project area in the future.
Ute Ladies’-Tresses Ute ladies’-tresses is federally listed as threatened. It is not found in the project area at this time. Populations have been found elsewhere in the state. The Ute ladies’-tresses orchid occurs in seasonally moist soils in wet meadows, springs, lakes, ponds, riparian areas, and old oxbows. Most sites are sub-irrigated and seasonally flooded, remaining moist into the summer.
Preble’s Meadow Jumping Mouse This species is federally designated as threatened. The mouse lives in heavily vegetated, shrub- dominated riparian habitats and immediately adjacent upland habitats along the foothills of the Front Range. The range includes Weld County, within the South Platte River basin. The mouse is not found in the project area at this time. The recovery plan for the Preble’s meadow jumping mouse describes their habitat as riparian areas within grassland, shrub land, forest, and mixed vegetation where dense herbaceous or woody vegetation occurs near the ground level, where available open water exists during their active season, and where there are ample upland habitats of sufficient width and quality for foraging, hibernation, and refuge from catastrophic flooding events. Although the mouse no longer exists within the study area, restoring riparian habitat that would be suitable for it as a result of this project and future projects may allow for the return of the species.
Mexican Spotted Owl Mexican spotted owls are listed as threatened. The owls favor secluded canyon bottoms and mixed coniferous forests, especially ponderosa pine with an understory of smaller pines or shrubs, more typical of mountainous terrain. Coniferous vegetation is sparse throughout the project area and Mexican spotted owls are not known to be present.
Bald Eagle While previously listed as threatened under the Endangered Species Act (ESA), the bald eagle was de-listed in 2007. However, this species is still protected under the Bald and Golden Eagle Protection Act as well as the Migratory Bird Treaty Act. These birds tend to construct their nests in mature trees near aquatic habitats, especially in cottonwood trees, and do nest in Weld County. One nest has been reported within approximately two miles of the project site, and the area provides year-round habitat for bald eagles. Additional riparian habitat and other habitat improvements could benefit existing bald eagles. 6.11.2 State-Listed Species The CPW website lists 19 bird species as threatened, endangered or of special concern in Colorado (2009). For Weld County, the list includes the state-threatened bald eagle, state-
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threatened burrowing owl, which would be found in prairie dog colonies near the Cache la Poudre River, state-special concern ferruginous hawk, state-special concern greater sand-hill crane, federal and state-threatened northern Great Plains piping plover, federal and state- endangered interior least tern, state-special concern long-billed curlew, state-special concern yellow-billed cuckoo, state-special concern mountain plover, state-special concern peregrine falcon, state-special concern western snowy plover, state-special concern swift fox, the federally threatened Preble’s meadow jumping mouse and endangered black-footed ferret, state-threatened river otter, state-special concern midget faded rattlesnake, state-special concern common garter snake, state-special concern northern cricket frog, state-special concern northern leopard frog and state-imperiled cylindrical papershell mollusk.
Figure 9. State special concern yellow-billed cuckoo
The bird species listed above primarily nest in riparian habitats and may benefit from establishment of multi-story riparian habitat within the study area. Non-avian species listed above are known to use riparian habitats, as well as wetland and open water habitats.
A state-listed species that could possibly be impacted is the burrowing owl. Fields that support prairie dog colonies may serve as home to the state-threatened burrowing owl. Burrowing owls nest in abandoned burrows within active prairie dog colonies. The burrowing owl is migratory and is typically found in northern Colorado between March 15th and October 31st of each year. Any construction must ensure that the owls are not present when the work is done. It is not known whether burrowing owls are now present on the proposed project footprints. Surveys would need to be done prior to construction.
The northern harrier hawk is a bird that is listed as a sensitive species by both the USFWS (in its list of Birds of Conservation Concern) and Colorado Partners in Flight. During field surveys, a northern harrier hawk was identified at the western end of the study area.
The northern leopard frog is a state species of concern. The voice of a northern leopard frog may have been heard on May 17, 2009; however, the lack of a confirmation sighting qualifies this as only a tentative identification.
6.12 Hazardous, Toxic and Radioactive Waste (HTRW) Considerations
No information is known that would indicate existence of HTRW concerns in the proposed project areas. One preliminary ecosystem restoration site was identified as a former auto
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junkyard, and the resulting potential for HTRW at that site contributed to the site’s elimination from consideration. An Environmental Condition of Property survey will be conducted.
6.13 Air Quality
Air quality in the region is influenced by a combination of factors, which include climate, meteorology, and density and geographic distribution of local and regional air pollution sources. The dispersion of pollutants is influenced by the properties of the pollutants as well as the way air masses interact with the regional topography. The U.S. Environmental Protection Agency (EPA), as a part of its requirement to enforce the Clean Air Act (CAA), uses six “criteria pollutants” as indicators of air quality and establishes a maximum concentration above which would adversely affect human health. These thresholds are called National Ambient Air Quality Standards. A designation of non-attainment indicates that an area does not meet these standards. In 1997 and 2008, Weld County was in a non-attainment zone for one pollutant within a designated timeframe and that was 8-hour ozone measurements. The EPA states these non- attainment measurements were marginal indicating they barely exceeded the standards threshold (2014). The county has been in attainment (meeting air quality standards) for all other measured pollutants. The state of Colorado does have a state implementation plan to meet the requirements of the CAA with regards to the interstate transport of the 8-hour ozone standard. State reports conclude that the transport of ozone and ozone precursors from Colorado does not cause or significantly contribute to non-attainment in, or interfere with maintenance by, any other state with respect to the 8-hour ozone standard.
6.14 Cultural Resources
Beginning in 1869, Greeley has produced numerous properties of local, state, and national historic significance. To date, within the Greeley area there are 17 individual properties and one district listed on the National Register of Historic Places (NRHP). The individual properties include churches, businesses, schools, courthouses, and the historic district of downtown Greeley. The Colorado State Register contains two individual properties and one district from the Greeley area. The Greeley Historic Register contains 85 properties. Of these 85 properties, 83 are individual properties and two are historic districts.
Forty-three properties have been identified in or near the proposed project area that may meet the criteria for listing on the NRHP. The Colorado Office of Archaeology and Historic Preservation have made official determinations on eight properties within the project area. One property is determined eligible for listing on the NRHP, seven properties are determined not eligible for listing on the NRHP, and the remaining properties are unevaluated. The properties within the project area consist of railroad lines, irrigation ditches, and residential properties.
A cultural resource survey is pending on the proposed project areas.
6.15 Social and Economic Resources
6.15.1 Demographics Greeley had a 2010 population of approximately 93,000; that is a 21-percent increase from the 2000 census, compared to a 17-percent increase in the state and a 10-percent nationwide. Weld
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County had a 2010 population of approximately 253,000, an even more robust 40-percent increase from 2000. The Front Range of Colorado has been undergoing rapid population growth over recent decades and is projected to continue similar growth. The following information reflects 2010 census data.
Minority ethnic groups comprise a larger portion of Greeley’s population than is the average in the state or the nation. Non-Hispanic whites are 59 percent of the population compared to 70 percent in the state and 63 percent nationwide. Greeley’s population is 36 percent Hispanic. Census tract 6, which contains most of the proposed FRM action area, is 67 percent Hispanic, compared to 21 percent in the state and 17 percent nationwide.
Per capita income in Greeley is approximately 78 percent of the national average and 71 percent of the state average. Median household income in Greeley is $41,845, which is 74 percent of state average and 80 percent of the national average. Median household income in the main proposed FRM area is $32,557, which is 58 percent of state average and 63 percent of the national average. Greeley has a poverty rate of 22 percent, and the proposed FRM area had a poverty rate of 35 percent compared to 12 percent for the state and 14 percent nationwide.
Rental properties are approximately 40 percent of Greeley residences. The homeownership rate is 60 percent compared to 68 percent in the state and 67 percent nationwide. In 2014, affordable housing is in very short supply, due to oil and gas development and September 2013 flooding in neighboring communities which displaced people and increased demand for housing. 6.15.2 Land Use A land use study for Greeley and vicinity was completed in June 2006. The study identified residential, commercial, public, and industrial land uses within the FEMA 0.2 percent ACE (500- year) floodplain, and an additional two-foot contour interval beyond that flood level. A land use survey gathered data on structure use, type of construction, structure size, condition, ground elevation, first-floor elevation, depreciated replacement value, and content value for each structure. Residential structures comprise 73 percent of total structures, while 27 percent of the land use in the study area is non-residential. These data were used to determine expected annual flood damages under existing without-project conditions.
In addition to existing conditions, most likely future conditions were forecast. The base year is the year when a project would be complete and first operational. The subsequent 50 years is the period of analysis, with the mean year for those future conditions being 25 years. Greeley’s 2020 Comprehensive Plan suggests it is unlikely that there would be significant changes in floodplain land use in the next 25 years. Future development will concentrate on the community fringe and outlying areas, outside the floodplain. No floodplain redevelopment was assumed because no projects were identified with a high likelihood of implementation, a firm location, or established commercial information. Thus, for purposes of this analysis it is assumed that existing level of development will remain the same for the next 25 years under future-without project conditions. Therefore, the economic existing conditions were carried through the base year and future conditions without change.
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6.15.3 Economic Damages Physical flood damages Under current conditions, approximately 450 structures, over half residential, show damage in the 0.2 percent ACE (500-year) flood; and 250 structures, show damage in the 1 percent ACE (100-year) flood event. Using forecast future water surface profiles, nearly 470 structures show damage at the 500-year event, and 285 show damage at the 100-year event.
Emergency and Disaster Relief Costs In addition to physical damages, there are non-physical costs associated with flood events. Emergency costs include those expenses that would not be incurred in the absence of flooding. Examples include emergency evacuation, increased costs of police, fire, military or medical services, flood fighting, and clean-up costs.
FEMA disaster response costs through the public assistance program include all or parts of emergency protective measures, road systems and bridges, water control facilities, public buildings, public utilities, parks, recreational and other activities of a governmental nature.
FEMA provides grants to assist individuals and families to find suitable housing when they are displaced in cases of federally-declared disasters. This assistance, being directly attributable to the disaster and being an expenditure that would not be undertaken except for the disaster, falls clearly under the emergency costs guidance of E-19(3)(c.) in Engineer Regulation 1105-2-100. Therefore funds expended by FEMA for temporary relocation assistance or reoccupation of a flood plain in the event of flooding are National Economic Development (NED) flood damages.
Total Annual Equivalent Flood Damages Equivalent annual damages were calculated using FY 2014 price levels, an interest rate of 3.5 percent, and a 50-year period of analysis. As computed in the HEC-Flood Damage Reduction Analysis (FDA) model, the expected annual damages for the entire study area under existing conditions are $1.275 million. The majority of those damages occur within the high damage reach.
In projecting future damages, the expected annual damage for each year in the analysis period is computed, discounted back to present value at the beginning of the base year and annualized to get equivalent value over the period of analysis. Equivalent annual damages are based on FY 2014 price levels, an interest rate of 3.5 percent, and a 50-year period of analysis. Estimated equivalent annual damages, which include future conditions, are $2.07 million for the study area.
6.15.4 Regional Economic Development (RED) Considerations Regional economic development (RED) considerations are factors affecting the regional economy while not necessarily affecting national economic outputs. Business shutdowns can last for weeks in large floods, causing sizable and even ruinous losses. Usually, business outputs lost due to floods can be replaced within a reasonable time by other locations of the company or other companies in the same industry. If production losses cannot readily be replaced, there can be an NED effect. Particularly affected would be construction jobs, which have been a strong part of the Greeley jobs base.
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Additionally, a flood event could cause the Island Grove Park area to cancel events. One of the largest events is the Greeley Stampede Rodeo. This annual ten-day event coincides with Independence Day; and features concerts, a professional rodeo, demolition derby, parade, fireworks show and more. It is estimated that over the ten-day period, two-hundred and fifty thousand local and out of town people attend and provide an impact of roughly $75 million to the local economy. 6.15.5 Public Safety More than 1,000 residents and more than 250 homes are in the 1 percent ACE floodplain. Dangers related to flooding can take the form of drowning, electrocution, illness from contaminated flood waters, and delay of ambulances or fire trucks due to road closures or inundation.
Greeley is located a considerable distance from the mountains where the significant snowmelt runoff originates; this allows days of warning time for evacuation of threatened areas before mountain snowmelt waters reach Greeley. Also, Greeley is located on a broad plain. As a result, by the time mountain runoff waters arrive they typically are broadly distributed and are greatly attenuated in depth and velocity.
Although floods originating from high mountain snowmelt would have ample warning time, the potential exists for flash flooding from rainfall runoff over the plains area. This area has been urbanizing rapidly and is projected to continue developing which will increase the frequency of flooding from rainfall events. This increased impervious area will increase runoff from rainfall events and increase the potential for flash flooding particularly along tributaries. Historically, there have been no reports of loss of life from flash flooding in Greeley. However, surrounding areas along the Front Range have a history of significant loss of life due to flash flooding as evidenced in the floods of 1935, 1965, 1973, 1976 and 1997.
6.15.6 Other Social Effects Possible social effects of chronic flooding of a community include:
Effects on emergency preparedness Long-term productivity effects, including maintenance and enhancement of resources for use by future generations Effects on the fiscal condition of the state and local sponsor Effects on real incomes Urban and community impacts Effects on population distribution and composition Displacement of people, businesses, and farms Effects on educational, cultural, and recreation opportunities
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6.16 Recreation
The Poudre River Trail is a concrete, 10-foot wide pedestrian and bicycle trail along the Cache la Poudre River. It is a regional trail, extending upstream to Windsor, and beyond into Larimer County, in total over 21 miles of continuous trail. Several trailheads are located along the trail. Within the Corps project area, it runs between Island Grove Park and the Poudre Learning Center just west of the Corps project area at 83rd Avenue. The Poudre Learning Center is used for environmental education for students in kindergarten through 12th grade from four area school districts, for college students from the University of Northern Colorado, and for the general population. The facility is also the headquarters of the Poudre Heritage Alliance, the managing entity for the Cache la Poudre River National Heritage Area. Sheep Draw Trail is another local trail, which runs along Sheep Draw and through the Hunters Cove West Natural Area.
Greeley has several plans for expansion of recreational facilities, independent of this study. A plan entitled City of Greeley Conceptual Trails Plan was prepared by EDAW, Inc. in 2002. The report provided conceptual trail alignments to guide future development and infrastructure improvements. The city plans to extend the Sheep Draw Trail to connect to the Poudre River Trail. Also, an extension of the Poudre River Trail is to be constructed between the confluence of the Cache la Poudre River and South Platte River, and Island Grove Park which is now the terminus of the trail. However, Greeley currently has no plans to develop trails into any of the areas proposed in this study for ecosystem restoration or similar areas. Without Corps ecosystem restoration, it is assumed that trail extension into these natural areas may not occur. Existing Poudre River Trail use has raised public interest in ecosystem resources and restoration, indicating these features would further support ecosystem restoration.
7. PLANNING CONSTRAINTS
No project specific constraints were identified for FRM planning. A number of limiting conditions were encountered, as described later regarding the screening and evaluation of measures.
A single constraint was identified for ecosystem restoration planning: avoiding the reach of the river near the Greeley-Weld County Airport.
No constraints were identified in recreation planning.
8. FRM PLAN FORMULATION
8.1 FRM OBJECTIVES
An overall goal of this study is to define a cost-effective flood risk management plan that promotes national economic development. Specific objectives for the planning period are:
Identify the NED Plan that maximizes net economic benefits for the study area. Reduce the risk of flood damages in Greeley.
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Minimize the long-term economic burden on Greeley and state of Colorado resulting from flooding.
8.2 FRM MEASURES
Measures that were investigated in feasibility included the following:
No Action: Corps taking no action and implementing no project. Upstream Dams: Store potential flood water in upstream reservoirs. Diversion Channels: Excavate a diversion channel from upstream of Greeley or the high damage area to downstream of Greeley. Gravel Pit Storage: Store potential flood water in completed gravel pits in the floodplain. The gravel pits would be maintained in an empty state, by lining them to prevent groundwater influx, and maintenance pumping. Channel Widening: Excavate channel banks wider to improve conveyance. Channel Sediment Removal: Excavate sediment from the channel upstream of bridges to improve conveyance. Bridge Replacement: Replace bridges with longer and higher bridges to increase conveyance. Levees: These would be focused along the high damage reach, but could be any configuration that would provide sufficient benefits. They would involve floodwalls where needed, and temporary closure structures to be installed in emergencies, across roads and railroads that the levees needed to cross. Elevate Structures: Move vulnerable properties above flood level by elevating them in place. Flood proof: Protect building walls and contents without elevating the buildings. Berms and Floodwalls: Build small berms or floodwalls. Buyout/relocation: Buy properties and remove structures, providing relocation as needed.
8.3 FRM PRELIMINARY SCREENING
Some measures were screened out without detailed economic evaluation and before being combined into alternatives. 8.3.1 Screening criteria The four Corps of Engineers’ planning criteria - completeness, effectiveness, efficiency and acceptability - are categorical criteria that characterize which measures to pursue. Examples of the application of the four criteria include:
Low Benefits: Obvious low benefits in terms of dollar value may mean a plan is not effective, not worth pursuing. Non-effective: Some measures can be readily recognized as being inadequate, or not effective in addressing study objectives. Engineering Feasibility: Technical impracticality indicates a plan is probably not effective or efficient. High Costs: Obvious high first costs may mean a plan is not efficient, not cost-effective, and this can eliminate some alternatives.
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Water Rights: These rights are fully appropriated in the area, are costly to acquire, and may lead to litigation. This is a consideration for measures which would require water rights or affect others’ water rights, impacting completeness and acceptability. Induced Damages: Adding levee protection in one area may induce damages in other areas, which can require costly mitigation in order to be complete. This high cost can be a screening factor. Sustainability: Operation and maintenance requirements should not be unreasonably high and unsustainable. This would indicate an inefficient plan. 8.3.2 Upstream Dams Building a large dam upstream would not be cost effective due to the high costs of the real estate and construction involved, as compared to the modest expected annual damages (EAD) in the 17-mile study reach. In addition, the environmental impacts of placing a large dam on the main channel of the Cache la Poudre River would be inconsistent with regional goals for restoration of the river. Further, dams would likely receive significant public opposition from agencies and other stakeholders concerned with environmental values. The Cache la Poudre River is the last major tributary to the Platte River System without main stem dams. Similar limiting factors would apply to large dams on major tributaries. Therefore, upstream dams were not carried forward. 8.3.3 Upstream Diversions Diversion of flood waters around Greeley would not be practical due to terrain and right of way issues. The Cache la Poudre River lies within a broad valley; therefore, large canals would be needed to carry excess floodwater around the community. Furthermore, bypassing the entire community would require diverting flood flows well upstream of Greeley, resulting in canals many miles long. Diversion would also require multiple wide crossings under the transportation infrastructure in the area. These requirements would incur large real estate costs as well as construction costs, which would clearly be disproportionately high relative to the estimated annual damages calculated for the community. Therefore, upstream dams were not carried forward. 8.3.4 Bypass Channel - Highway 85 Expressway Bypass The Highway 85 Expressway embankment is the main cause of backwater during floods downstream of the Union Pacific Railroad embankment and is the reason why channel widening alone could not be effective in that reach. An excavated bypass channel would branch off the Cache la Poudre River between 6th Avenue and the U.S. Highway 85 bypass, flow under the expressway through a bridge or large culverts, and rejoin the Cache la Poudre River downstream from the wastewater treatment plant. Several possible routes for a bypass channel were considered. A diversion structure would be required to control flow into the bypass channel.
Based upon initial economic analysis, it appeared unlikely that this bypass channel could be justified. Very low net annual benefits were computed for levee alternatives focused downstream from the diversion point. The additional benefits that would be captured in the upstream reach, by the bypass channel, were incrementally insufficient to support the much larger costs of the bypass channel, including excavation and associated four-lane bridge or large culverts. The bypass channel was not carried forward.
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8.3.5 Channel Sediment Removal The Greeley reach of the river is generally aggrading through sediment deposition in the channel. Aggradation will cause higher flood stages compared to current conditions. The sediment could be mechanically removed to maintain channel capacity and limit increases in future flood stages. However, sedimentation is a perennial process, so sediment removal would need to be done indefinitely. This would involve removing large volumes of sediment at a high cost that would be burdensome and perhaps unsustainable. In addition to the high cost associated with sediment removal, minimal benefits at less frequent floods would be realized. Therefore, this measure was not carried forward. 8.3.6 Bridge Replacements Bridge replacements would remove flow restrictions and thus reduce flood stages in specific reaches. However, the distribution of costs and benefits for the high damage reach indicated that no bridge replacement would be justified by the flood damage reductions. As a result, bridge removal was not evaluated. For future bridge replacements that are dictated by other reasons, increasing the span to accommodate a wider channel should be considered by the design agency.
8.4 FRM PLAN EVALUATIONS
After the preliminary screening, the remaining measures were evaluated in greater detail to more closely assess feasibility. Measures carried forward for further screening included:
No Action: Corps taking no action and implementing no project. Gravel Pit Storage: Store potential flood water in abandoned gravel pits in the floodplain. The gravel pits would be maintained in an empty state, by lining them to prevent groundwater influx, and maintenance pumping. Channel Widening: Excavate channel banks wider to improve conveyance. Levees: These would be focused along the high damage reach, but could be any configuration that would provide sufficient benefits. They would involve floodwalls where needed, and temporary closure structures to be installed in emergencies, across roads and railroads that the levees needed to cross. Elevate Structures: Move vulnerable properties above flood level by elevating them in place. Flood proof: Protect building walls and contents without elevating the buildings. Berms and Floodwalls: Build small berms or floodwalls. Buyout/relocation: Buy properties and remove structures, providing relocation as needed. 8.4.1 No Action Alternative This is the alternative of the Corps taking no action and implementing no project. In the absence of a Corps project, and perhaps even with some types of Corps projects, the primary role in flood risk management will be played by local governments. Actions expected include floodplain management, emergency management, public education, and flood fights. Floodplain management through regulation as discussed in a previous section would be part of the no action alternative. Greeley has an established Emergency Operations Management program. Other components are discussed here.
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Emergency management can include public education, flood warnings, evacuations, advance measures and other flood fighting, and cleanup and recovery. Greeley will continue to “flood fight” future Cache la Poudre River floods. The Corps of Engineers has not participated in advance measures at Greeley. Flood fighting in previous floods has consisted largely of evacuations and construction of ring levees around selected buildings; this action would be expected in future events. The length of protection needing sandbags, for the high damage reach and other areas of the city, complicates successful flood fighting, and the outcomes of future flood fights are unpredictable. Additionally, the long duration of major flooding makes underseepage a threat to flood fight success. Also, extended closure of many city streets could have economic impact similar to inundation of the streets. For these reasons, the flood fight alternative is incomplete, ineffective, and inefficient.
This measure was carried forward for further analysis. 8.4.2 Gravel Pit Off-Channel Flood Storage The potential to store significant portions of flood hydrographs in off-channel reservoirs upstream of the high damage reach was investigated. This alternative involved constructing a concrete weir to divert the flood peak from the river, into gravel pits 20 to 40 feet deep, upstream of the high damage reach. The pits would be lined with concrete to exclude groundwater. A pump would dewater the gravel pits after floods; this could take 30 days, and this duration of detention might require a water right.
The volume of water that could be diverted off peak discharge was computed for floods of various return periods. Table 8 lists the volumes needed to reduce peak discharges to a lower return period for several flood and storage scenarios.
Table 8. Volumes needed to reduce peak flows to a lower return period Storage Needed to Lower Volume to Corresponding Return Period (acre-feet) 20-Year 10-Year 5-Year 2-Year Return Period / Flow (4,880 cfs) (3,920 cfs) (3,020 cfs) (1,810 cfs) 100-Year (10,100cfs) 13,000 48,100 ------50-Year (7,420 cfs) 5,660 28,900 ------20-Year (4,880 cfs) ------7,520 30,300 ------10-Year (3,920 cfs) ------14,180 47,600
It was determined that gravel pit space available was significantly insufficient to capture the 100- year flood, and other measures would still be needed. Reducing a 50-year event volume to a 10- year event volume, or a 20-year event to a 5-year event volume, would require approximately 1,000 acres of gravel pits with average 30-foot depth. Construction and real estate costs to modify the gravel pits would be disproportionately large. Gravel pit storage would be impractical and not cost-effective. 8.4.3 Channel Widening Channel widening was modeled, to evaluate the potential decrease in flood stage by excavating wide benches above the two-year peak flood stage. Channel widening was found to have benefits, although not sufficient to serve as a stand-alone measure. It would not move the 100-
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year floodplain away from existing residents and businesses. Water surface elevations could be lowered somewhat at many locations. Stage reduction on the improved high damage reach averaged approximately 0.4 feet for the 10-year event to nearly 0.5 feet for the 100-year event. Maximum stage reduction was at the 50-year event, with an average of 0.6 feet.
The main restraint on channel widening potential is the many bridges along the reach. The city acted on some of the recommendations of a 1986 Warzyn report and raised elevations of several major bridges when they came up for replacement. However, the widths remain narrower than channel widening would be designed. These bridge openings, and the bridge approach embankments across the floodplain, still significantly raise stages in a major flood event. The road embankments and bridges would negate most of the gain in conveyance that could be obtained by widening the channel upstream of those bridges. Channel widening would be ineffective alone. 8.4.4 Levees Numerous levee configurations were formulated at the conceptual level. For all levee alternatives, a channel improvement component was included, as a bench terrace cut just above the two-year stage. These levee concepts were screened based on criteria such as length of reach improved or protected, width of channel improvements needed, and level of protection provided. A total of eight levee alignments were ultimately evaluated in some detail.
The design assumed for analysis included interior drainage features. Levees may prevent drainage of interior runoff that would normally drain to the river. To prevent flooding inside the levee by local runoff, a drainage structure, ponding area, and in some cases a pump, were included in levee costs. The drainage structures were sized to not significantly increase expected annual damages from interior flooding compared to without-project conditions.
Three alternatives known as 1, 1A, and 5 were partly located in the regulatory floodway (Figure 10). This invoked the FEMA requirement to mitigate any building impacted by increased base flood (1 percent annual probability flood) profiles due to development in the floodway.
8.4.4.1 Levee Alternative 1 Alternative 1, the shortest levee alternative, focused on the two damage reaches with the highest EAD, from 8th Avenue to near 17th Avenue. Tie-offs extend laterally from the river to prevent flanking.
8.4.4.2 Levee Alternative 1A Alternative 1A includes Alternative 1 and an additional left bank levee to prevent induced damages from the right bank levee.
8.4.4.3 Levee Alternative 5 Alternative 5 includes all features of Alternative 1a with an added right bank levee continued downstream to just upstream of the Highway 85 Bypass. The levee was aligned such that it could be constructed in phases.
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Figure 10. Floodway levee alignments
Preliminary estimates showed that none of the three plans would be economically feasible. Subsequent findings regarding interior drainage requirements indicate that those initial costs would need to be adjusted upward substantially, and the levees would be even less feasible than originally estimated.
Additional levee alignments set back from the floodway were formulated. More than a dozen right bank levee concepts were identified along the high damage reach; these were screened down to a few by comparing relative gains in each to the relative cost increases. All alignments were essentially the same in the eastern portion of the levee; they differed in the alignment of their western portions. Some of the alternative alignments are shown in Figure 11 below.
Figure 11. Setback levee alignments
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8.4.4.4 South Levee Alignment The South Levee Alignment Alternative was an approximately 1.36-mile long levee with two road closure structures and one road raise. North 14th Avenue would be closed at the levee. It would extend from east of North 8th Avenue on the downstream end to North 16th Avenue on the upstream end. Underseepage control would be provided by toe drains.
8.4.4.5 Short South Levee Alignment After a review of benefits and cost of the South Levee Alignment, it became evident that there were fewer benefits to be had west of 12th Avenue, but that considerable cost in land acquisition and construction would be encountered with interior drainage issues related to the 14th Avenue storm sewer basin. A shorter levee alignment, which ties off to high ground near 12th Avenue was developed. Structures west of the tie-off would be considered for nonstructural flood risk reduction.
8.4.4.6 Middle Levee Alignment The Middle Levee Alignment Alternative was an approximately 1.39-mile long levee with four road closure structures and one road raise. It extends from east of North 8th Avenue on the downstream end to North 16th Avenue on the upstream end. One major feature of this levee was that it crosses D Street and does not require the taking of houses on the south side of D Street. Including that additional area behind the levee requires an additional closure structure across D Street. With this levee alternative, North 14th Avenue would remain open, and there would be another diagonal road closure structure across the intersection of North 14th Avenue and D Street. Underseepage control would be provided by toe drains.
8.4.4.7 North Levee Alignment The North Levee Alignment Alternative adjacent to the Grandstand Alternative was an approximately 1.60-mile long levee with three road closure structures and one road raise. It extends from east of North 8th Avenue on the downstream end to North 17th Avenue on the upstream end. The major feature of this levee was that it includes most of the Island Grove Facility inside the levee. A fourth closure structure was designed to be installed through the Island Grove arena, running just behind the grandstand. The grandstand closure structure would largely be out of sight and would be erected when flooding was imminent. With this levee alternative, North 14th Avenue would remain open. Underseepage control would be provided by toe drains.
8.4.4.8 North Levee Alignment With Floodway Shift At the request of the sponsor, a fifth concept was developed to keep Island Grove Park protected. This placed a levee in the floodway but the concept included intentionally shifting the floodway north, to the left overbank area where development was minimal. This involved channel excavation and lowering portions of the berms around two old non-operational gravel pits. A significant cost was the need to acquire the two gravel pits, which have been lined in anticipation of a water storage application.
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Preliminary estimates were prepared for real estate costs (Table 9). Annualized estimates of damages, benefits and costs assumed the FY 2014 federal interest rate of 3.5 percent and a period of analysis of 50 years. All cost estimates were expressed in FY 2014 prices. The calculated benefit/cost ratios showed that none of the plans were economically feasible.
Table 9. Benefit/cost calculations for setback levees Structural Alternatives S outh Short South Middle North Shift PROJECT BE NEFITS: Equivalent Annual Da mages: Without Project $2,068.33 $2,068.33 $2,068.33 $2,068.33 $2,068.33 Equivalent Annual Da mages: With Project $1,196.19 $1,252.93 $1,210.65 $1,125.65 $1,117.57 TOTAL ANNUAL PROJECT BENEFITS $872.14 $815.40 $857.68 $942.68 $950.76
First Construction Costs $11,599.63 $10,487.60 $13,246.82 $15,300.92 $13,753.01
Pla nning, Engineering, and Design $1,043.97 $943.88 $1,192.21 $1,377.08 $1,237.77 Administration Service Costs $695.98 $629.26 $794.81 $918.06 $825.18 Construction Continge ncy (30%) $3,479.89 $3,146.28 $3,974.05 $4,590.28 $4,125.90 Subtotal: Construction Costs: $16,819.46 $15,207.01 $19,207.89 $22,186.34 $19,941.87
Land, Easements, Relocations, Real Estate, Disposals (LERRDS) $3,559.80 $3,315.78 $3,705.74 $3,886.20 $4,524.88 LERRDS Contingency Costs (30%) $1,067.94 $994.74 $1,111.72 $1,165.86 $1,357.46 P.L. 9L646 Relocation Costs (contingency included) $526.42 $526.42 $225.02 $225.02 $225.02 Subtotal: First Investment Costs $21,973.62 $20,043.96 $24,250.38 $27,463.42 $26,049.23 Interest during Construction (2 years at 3.5%) $675.89 $616.53 $745.92 $844.75 $801.25 Total First Investment Costs $22,649.50 $20,660.49 $24,996.29 $28,308.16 $26,850.48
Total Annua lized Investment Cost (50 years, 3.5%) $965.63 $880.83 $1,065.68 $1,206.88 $1,144.74 Annual OMRR&R $31.23 $31.23 $31.23 $31.23 $31.23 TOTAL ANNUAL PROJECT COSTS $996.86 $912.06 $1,096.91 $1,238.11 $1,175.97
NET ANNUAL BENEFITS ($124.72 ) ($96.66 )($239.24 ) ($295.43 ) ($225.20 )
BENEFIT/COST RATIO 0.87 0.89 0.78 0.76 0.81
8.4.5 FRM Nonstructural Alternatives - Residential Modifications Nonstructural measures are those which reduce flood risk by changing characteristics of the population and property at risk, rather than changing characteristics of the flooding. Physical measures are modifications to buildings to make them less vulnerable to flood damages, or the outright removal of the buildings from the flood hazard area.
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8.4.5.1 Screening Measures that could be considered for residential buildings include dry flood proofing of the building, ring levees or floodwalls, raising the buildings in place, relocating the buildings, and buyout and removal of buildings. Only elevating in place was evaluated as the appropriate measure for residences. No other measures would meet NFIP requirements and so would not lower insurance costs for owners. Also, berms or ring levees would be too large for most residential lots. Floodwalls would have disproportionately high cost relative to the values of the houses. Relocation would require available lands outside the floodplain and could have community cohesion impacts. Therefore, elevating in place and buyout were the measures evaluated for residences.
Initial consideration was given to mobile homes, especially the mobile home park on 11th Avenue adjacent to the river. Roughly half of these existing mobile homes are in the designated floodway. Elevating these structures would constitute a substantial improvement and would not be permitted in the floodway. The underlying property on which these units rent lots is valued as income property, making its acquisition cost prohibitive.
8.4.5.2 Design Design assumptions used for elevating in place varied according to the foundation type of each specific residential building. Structures on a crawl space or slab would be raised in place on a new foundation, and the foundation area would be filled with clean run fill material. For structures on an existing basement, but with a first floor above a particular flood level and not subject to damage, then the only measure would be to convert the basement to non-living space, by filling it with sand. This would involve relocating any basement utilities to the elevation above flood level, by providing a 50-square-foot addition, with the main floor. The basement area would be filled except for a small storm shelter space. However, if the first floor of a basement house was below flood levels and subject to damage, then the house would be raised as well as filling the basement as described above. Garages and sheds would not be modified and would remain vulnerable to flooding. Figure 12 provides examples of elevated structures.
Figure 12. Samples of a residence elevation in place
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8.4.5.3 Costs The cost to elevate residential buildings was estimated by utilizing equations based upon building square footage, flood proofing height and foundations type. The main cost factor in elevating houses is the actual raising of the house. This involves placing beams under the house, jacking these up slowly, and placing cribbing beneath; also new foundation walls with vents, steps and landings, and utility extensions would be needed. Estimates for a crawlspace foundation type were the least costly. Upward adjusted factors were used to reflect the higher costs involved in raising slab or basement foundation types. For all foundation types, elevating cost for each house was based on the square footage of the house, and was adjusted upward proportional to the actual height it was being raised. Height of elevation needed was based on future water surface profiles at each specific house. In addition to the house raising cost, other cost factors for basement type houses were the utility elevating cost, basement fill cost, and storm shelter cost. For all houses being elevated, a temporary housing cost was estimated for residents to be accommodated elsewhere during the work.
The equation for computing residential elevation costs is a modification by Omaha District Cost Engineering of a cost estimate procedure developed by FEMA’s Hazard Mitigation Grant Program (HMGP) and given in: “Office of Community Development, Disaster Recovery Unit, Hazard Mitigation Grant Program, Procedure Number 1, Revision Number 11, 01/15/2013.” The Omaha District Cost Engineering formula for determining costs for elevating a residential building for flood risk reduction is:
Elevation Cost = (HCF + AUC + SRC) x ACF x SF, Where:
HCF = FEMA HMGP cost per square foot, based on foundation type and height of raise AUC = Additional utility cost per square foot SRC = Site restoration cost per square foot ACF = Area cost factor SF = Footprint of residence to be raised, square feet
Open foundation costs are applicable to buildings on basements walls or on foundation walls with a crawl space. Slab separation is a technique for raising a slab on grade residence by separating the building superstructure from the foundation slab. Slab raise involves raising the foundation slab and the superstructure as one unit.
Buyout costs would include the value of the property, Corps and sponsor administrative costs, housing assistance for low-income tenants, lot clearing, and long term maintenance by the city. 8.4.6 FRM Nonstructural Alternatives - Nonresidential Modifications
8.4.6.1 Screening Measures that could be considered for nonresidential commercial or public buildings include dry and wet flood proofing of the building, ring levees or floodwalls, relocating buildings, and buyout and removal of buildings. Raising in place is not normally feasible, due to these buildings’ size, and the need to provide for vehicle access such as at garages or loading docks.
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Relocation is highly problematic in the need to provide similar suitable location and infrastructure. Berms or ring levees often do not fit within the property lines without diminishing the business’ productive property area. Floodwalls are disproportionately costly for most businesses in the affected areas. Therefore, dry and wet flood proofing were the measures evaluated for commercial structures, while a floodwall was considered for a cluster of public buildings.
8.4.6.2 Design All potentially feasible (cost-justified) commercial buildings were surveyed to determine their specific design, type, and external configuration. The choice whether to estimate use of dry or wet flood proofing was based on those factors. Some structures deemed suited to wet flood proofing were also assumed to contain a smaller interior area that would be dry flood proofed, to provide protection for such valuables as critical records or valuable inventory or equipment. Dry flood proofing would include waterproofing the exterior wall, constructing a masonry veneer over that water seal, closure panels for doors and other openings, a sump pump inside the building, and sewer anti-backflow valves.
Wet flood proofing would include modifying interior walls to water proof them, insulation, wainscoting, raising of electrical utilities, flood vents, and sewer anti-backflow valves. Because this method allows water to flow through a building and to contact contents, no sump pump is needed.
Some buildings inventoried have metal exterior walls. To provide sufficient wall strength, new concrete “short walls” would be built on a new foundation immediately outside the steel walls. Waterproof sealant would be applied to the concrete wall and closures for openings would be built into the wall.
To be considered nonstructural, flood barriers such as a floodwall cannot raise the water surface elevation of the 1-percent ACE flood by any more than 0.00 foot, and should be constructed to no higher than five feet above grade. The floodwall for the three county buildings was designed to approximately three feet tall. Floodwalls may require drainage systems and pumps to evacuate seepage and interior drainage, but this was not determined for structures in this analysis. Figure 13 provides an example of a floodwall and dry flood proofing.
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Figure 13. Samples of floodwall and dry flood proofing
8.4.6.3 Costs Construction costs were estimated for each design element described above. Each building’s size, as determined by survey, determined the length of waterproofing, wall veneer, and number and size of closure panels to be estimated for that building. In the case of the cluster of three Weld County buildings, the needed length of floodwall was based on approximate measurement. The needed height of each building’s waterproofing treatment and of the floodwall was based on future water surface profiles at each specific structure. Each structure was estimated separately from others on a given property, except for the three county buildings treated as one unit. Cost factors included in the floodwall cost were earthwork, concrete floodwall, footing and foundation wall, and closure panels.
No real estate cost was included; only a temporary right of entry for construction would be needed, at minimal cost. It is assumed that business locations justified for flood proofing would remain in operation and continue to conduct business while the work was being completed. 8.4.7 FRM Nonstructural Alternatives – Floodplain Management Measures Non-physical, nonstructural measures consist of programs, systems, or activities such as flood insurance, flood warning and evacuation, floodplain regulations preventing unsuitable development in flood hazard areas, and flood preparedness planning. Only floodplain management and zoning would remove potentially damaged structures from the floodplain.
Floodplain Management and Zoning – As described under the no action alternative, Greeley is currently practicing solid floodplain management and uses zoning to prevent development in the floodplain from creating new hazards. Some undeveloped land remains in the Special Flood Hazard Area (SFHA) of the Cache la Poudre River that is not in the regulatory floodway. The city’s regulations will require that nonstructural measures be used to reduce the potential future
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flood damages to any new building to be built in the SFHA. The most effective nonstructural measure is likely to be construction of the first floor of buildings to at least one foot above the 100-year flood elevation. Commercial buildings could be elevated and flood proofed to the minimum requirement. Since this measure is currently being used extensively and it is anticipated that it will be used in the future, it is considered to be part of the existing and future conditions scenario, rather than a measure for implementation within the context of a formulated plan.
More potentially can be done through nonstructural flood damage reduction efforts at some of the more vulnerable properties. Properties in the floodway can be purchased and removed. Properties in the floodplain and flood fringe can be flood proofed and elevated.
Flood Warning and Evacuation – Due to the relatively long warning that Greeley has for a major out of bank flood, flood warning as a standalone measure would not be highly productive. Flood warning systems are typically implemented when there is a significant threat to life and minimal time to react to a hydrometeorologic event. The situation in Greeley is much the opposite. The threat to life is minimal due to the relatively shallow flood depths and long warning times provided by floods which overtop the banks of the Cache la Poudre River. Flood warning as a measure potentially could be used on tributary streams in Greeley, or in conjunction with any recreational trails that are located under bridges, where more rapid rises in stage may pose a threat to life. 8.4.8 FRM Nonstructural Evaluation Using future condition water surface profiles, nearly 470 structures show damages at the 500- year flood event, and 285 show damages at the 100-year event. For these, a simple minimum cost/maximum-affordable project (based on EAD) calculation was made, using the HEC-FDA model’s structure detail report. Structures with minimal or no damages were screened out from further analysis. Costs were developed for the remaining 190 structures that had greater damages, and these were modeled in HEC-FDA. These included approximately 115 residential structures and 75 non-residential structures. For non-residential which contained both wet flood proofed and dry flood proofed portions, the two methods were estimated separately and summed together for one building cost. Separate buildings on one property were evaluated separately, and as a result, often differed in justification. Of the 190 structures evaluated, the evaluation identified up to 70 structures with a positive benefit/cost ratio (BCR) greater than 1.0.
Buyout costs were evaluated for every residential structure that showed a positive BCR for elevating in place. The calculated buyout cost would exceed cost for elevation in place, in every instance evaluated. Therefore, only elevating in place was carried forward in the final array, for optimization of the most cost-effective level of flood protection for residential structures. Due to its location in the designated floodway, one of those houses could not be raised in place, but would be offered a buyout instead. The estimated cost of buyout for this property still produces a positive BCR for this property.
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8.5 FRM COMPARISONS – OPTIMIZATION
Project benefits were modeled for a range of flood protection levels, to determine at which level the project would provide highest net annual economic benefits (Table 10). For this analysis, the HEC-FDA model was run with risk and uncertainty for levels of protection at the 2 percent (50- year), 1 percent (100-year) and 0.2 percent (500-year) ACE events. When a given flood level was run, all buildings were assumed to be protected at the same level. The “structure detail out” report of the HEC-FDA model was used to calculate EAD for individual structures. This did not include the Corps’ required risk and uncertainty analysis, because HEC-FDA does not allow for ready application of the process on every individual structure in a large plan. Instead, risk and uncertainty analysis was applied later in the aggregate on the final three nonstructural alternatives.
Only individually justified structures would be included in the plan at each level of protection. Any plan would thus be collectively justified; the only variables are the structures included and the cost and benefits. The calculation of costs and benefits at each flood level indicated 70 structures are economically justified at the 50-year level, 69 at the 100-year level, and 64 at the 500-year level. There is some slight change among these, in which structures are included in each group, as described below.
Some houses justified for the 2 percent (50-year) ACE level protection required only filling of their basements; this is because their first floors are estimated to not be inundated at the 2 percent (50-year) ACE level of flooding. Moving up to the 1 percent (100-year) ACE flood level, five of those residences then receive first floor flooding, so require being raised, and become infeasible. However, another four structures were added at the 1 percent (100-year) ACE level because they would receive enough damage to justify elevation. These included one residence and four nonresidential structures, three of which are the Weld County buildings to be surrounded by one floodwall.
Moving up to the 0.2 percent (500-year) ACE flood level, another four residences would receive first floor flooding, so require being raised, and become infeasible. However, the higher flood level would produce higher damages on the other buildings, while the elevating costs would increase at a lower rate than the damages. Therefore, the 0.2 percent (500-year) ACE level of protection provides the highest annual net benefits, indicating the optimal level of flood to address is the 0.2 percent (500-year) ACE level.
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Table 10. Optimization data for three flood levels ANALYSIS WITH RISK AND UNCERTAINTY 0.2 (50 yr) 0.01 (100 yr) 0.002 (500 yr) PROJECT BENEFITS: Equivalent Annual Damages Without Project $2,068.33 $2,068.33 $2,068.33 Equivalent Annual Damages With Project $1,682.78 $1,631.19 $1,551.81 TOTAL ANNUAL PROJECT BENEFITS $385.55 $437.14 $516.52
First Construction Costs $3,288.41 $3,715.47 $3,755.72 Land, Easements, Relocations, Real Estate, Disposals (LERRDS) $557.93 $541.26 $520.42 Subtotal: Construction and Real Estate $3,846.34 $4,256.73 $4,276.14 Contingency Costs (20%) $769.27 $851.35 $855.23 Total Construction and Real Estate $4,615.61 $5,108.08 $5,131.37 Planning, Engineering, and Design (9%) $415.40 $459.73 $461.82 Supervisory and Administrative (6%) $276.94 $306.48 $307.88 Subtotal: First Investment Costs $5,307.95 $5,874.29 $5,901.07 Interest during Construction (1 year at 3.5%) $69.17 $76.55 $76.90 Total First Investment Costs $5,377.12 $5,950.84 $5,977.97
TOTAL ANNUAL PROJECT COSTS (50 years @ 3.5%) $229.25 $253.71 $254.86
NET ANNUAL BENEFITS $156.30 $183.43 $261.66 Number of structures:706964 BENEFIT/COST RATIO 1.68 1.72 2.03 8.6 FRM TENTATIVELY SELECTED PLAN / NATIONAL ECONOMIC DEVELOPMENT PLAN
The 0.2 percent (500-year) ACE nonstructural FRM plan has the highest annual net benefits, and so is the tentatively selected NED Plan. The 64 eligible structures in the plan include 44 residences, 17 commercial structures, and 3 county buildings. None of the commercial properties proposed are engaged in a business allowed by Colorado law that is contrary to Federal Law. The 64 eligible properties are found across an eight-mile reach, but are highly concentrated in the high damage reach, with 52 being within a one-mile square area (Figure 14). One of the eligible residences is in the designated floodway and would be offered a buyout rather than elevation (Figure 15).
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Figure 14. Concentration of TSP structures near Rodarte neighborhood
Floodway buyout candidate
Concentration of eligible structures shown in Fig. 14.
Figure 15. 0.2 percent (500-year) ACE floodplain and structures included in the TSP
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9. ECOSYSTEM RESTORATION (ER) PLAN FORMULATION
The Cache la Poudre is a nationally significant ecosystem. In particular, the Cache la Poudre as a Front Range river provides critical habitat linkages from the Rocky Mountains to plains river systems and habitats. Especially critical habitats include riparian corridors that provide migration, breeding, and rearing habitat for numerous bird and native species. Riparian areas account for only three percent of Colorado’s land area according to USFWS, or less than one percent according to CPW; yet they form essential habitat for over 50 percent of Colorado’s bird species. This region has experienced significant habitat losses with losses of over 70 percent of riparian forest and 50 percent of wetlands state-wide with even higher percentages in urban areas. Restoration of wetland and riparian resources can provide critical floodplain and river corridor connections including wetland habitat, riparian habitat, habitat for state-listed threatened and endangered species, and international migratory bird habitat.
Prior to European settlement, the Cache la Poudre River was characterized by high spring flows, thunderstorm runoff in early summer, and significantly lower flows later in the year. This flow regime perennially reworked the form of the channel and floodplain, creating diverse channel and riparian habitats, to which native species were adapted.
After European settlement, multiple developments began altering and degrading the natural communities. Wood cutting, clearing for farming, stream channelization, irrigation diversions, dams, gravel mining, and levee-type systems have resulted in erosion, degradation, and destruction of riparian and wetland habitats. This can be expected to continue for the foreseeable future as the population and commercial development continue to increase.
In 1998, Greeley began an effort to retain areas with natural ecosystems for Greeley and its surrounding Weld County growth area. Through an Open Space Advisory Committee, Greeley produced the Greeley Open Space System Plan and Implementation Program. This set out objectives to restore many of the riverine and riparian resources: the river/floodplain connection, wetland habitat, riparian habitat, habitat for federally-listed threatened and endangered species, National Heritage Program Species, state species of concern, migratory bird habitat, and a connective corridor between the South Platte River and the Front Range. It also sought related ecosystem education opportunities.
9.1 ER OBJECTIVES
The following are meant to be specific and measurable actions which would restore habitat that is in the federal interest. 9.1.1 Migratory Bird Habitat Objectives Reestablish a hydrologic connection to riparian habitat areas; surface or groundwater. Increase density and canopy cover of woody vegetation near water. Reestablish plains cottonwood and peachleaf willow trees as well as native riparian shrubs, herbs, and grasses. Remove Russian olive and Siberian elm in riparian areas where they are decreasing habitat value.
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Reestablish trees, shrubs, and understory in order to create a multi-story habitat structure in riparian zones. Establish small and large patches of riparian habitat adjacent to open water and wetland and grassland habitats to create a mosaic of habitat types. By accomplishing the above objectives, reduce habitat fragmentation and increase connectivity of riparian habitat along the riparian corridor. Minimize impact from adjacent human activity. Develop a riparian corridor along the Cache la Poudre River, increasing connection between the ecosystem of the South Platte River to the east and the mountainous ecosystem of the Front Range to the west. 9.1.2 Wetland Objectives A limiting factor in the study area is the rarity of water that is not already appropriated for non- ecosystem purposes. Virtually all surface water in the river basin, even during very high discharges, is appropriated to water rights holders through a state system. Therefore, an objective to increase watered area, by surface impoundment or excavation to groundwater, could infringe on existing water rights. Water rights are difficult and costly to acquire, and easily become the subject of litigation. Therefore, increased surface water wetlands were ruled out as an objective. However, floodplain wetlands also take the form of temporary, seasonal, intermittent, and groundwater-supported wetlands. The objective for wetlands, therefore, was to increase the quantity and quality of those types of wetlands.
Restore wetland hydrology in degraded wetlands such as oxbows and swales, whether by surface water or groundwater. Restore a variety of hydrologic regimes within target areas, to increase diversity of vegetation and wildlife benefits. Restore diverse native wetland species. Establish small and large patches of wetland habitat adjacent to open water and riparian and grassland habitats to create a mosaic of habitat types.
9.2 ER MEASURES
Measures that were considered for achieving the objectives above, for restoring the various lost and degraded habitats, include:
Excavate to restore river hydrologic connection to oxbows; use diverse elevations to achieve diverse hydrologic conditions. Install river diversion structures to divert river water to floodplain areas. Excavate to restore river meanders. Supplement floodplain hydrology by using storm water. Excavate below groundwater for permanent wetlands. Excavate and grade to increase runoff into historically wet depressions. Plant and seed riparian and wetland plants. Establish plains cottonwood and peachleaf willow as well as native riparian shrubs, herbs, and grasses in multi-story communities. Rely on natural recruitment of cottonwoods and willows following restored hydrology.
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Re-grade the river bank to more natural contours. Excavate near groundwater for riparian habitat. Remove invasive vegetation of low value; Russian olive, Siberian elm, reed canary grass. Construct fencing to exclude livestock from restored habitat and from river and banks. Convert an old floodplain reservoir to a mixture of riparian wetlands and buffer habitat.
9.3 ER OPPORTUNITIES AND SCREENING
Existing habitat types, and wetland and riparian restoration opportunities, were identified, quantified, and mapped. Existing habitat was classified as shown in Table 11 below.
Table 11. Habitat types within the study area
Habitat Type Acres Open Water - River Channel (Area within OHWM) 92
Gravel/Sand Bars within River (also located within 34 OHWM) Open Water - Ponds, Lakes, Reservoirs 477 Open Water - Regional Irrigation Ditches 18 Cattail-Rush-Sedge Wetland 125 Reed Canary grass Wetland 39 Shrub Riparian Wetland 29 Riparian Forest 292 Exotic Riparian Forest 15 Grass/Forb Mixed Rangeland 300 Ruderal Rangeland 1,630 Agricultural 2,202 Disturbed 1,485 Developed 1,028 Residential 634
Table 12 shows the measures applicable to achieving the objectives, and the metrics for measuring success in the objectives.
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Table 12. Relating objectives to measures and performance criteria Monitoring criteria / Objectives Measures Performance metrics Restore cottonwood / Remove invasive species willow tree & shrub Percent of area canopy cover Plant trees/whips cover, 100 meters near within 100 meters of water Create conditions for natural succession river Excavation, to diverse elevations Percent cover w/in 1 meter Restore oxbows, wet Water diversion of shoreline swales, and other riparian Slow conveyance of runoff water to river Suitable hydrology wetlands Plant hydrophytes and adjacent riparian Percent native hydrophytes and grassland plants
Increase habitat Increase extent and proximity of suitable Measure areas of suitable connectivity habitat habitat and spacing
Increase species diversity Remove invasive species Floristic Quality Index, and habitat integrity Plant native species number of species / diversity
Structural diversity Plant variety of emergent, shrub and trees Document and map strata
9.3.1 ER Constraints or Limiting Factors Some areas and measures were screened out without detailed economic evaluation and before being combined into alternatives. The Greeley-Weld County Airport is adjacent to the most downstream reach of the Cache la Poudre River. Due to concerns over airplane bird strike risks, it was determined to avoid any ecosystem restoration activities in that reach of the river (Figure 16). The airport and Federal Aviation Administration (FAA) have approved the remaining restoration study area.
A large gravel pit area immediately north of Greeley was screened out due to multiple existing development plans that would compete with and complicate a restoration project (Figure 17). Mined pits are increasingly being used for residential development and water storage.
Removal of the airport reach and gravel pit reach screened the study area down from 17 miles to approximately 9 to 10 miles.
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Figure 16. Greeley - Weld County Airport reach
Google Earth
Figure 17. Gravel pit area avoided 9.3.2 Screening criteria The remaining areas were screened to identify primary opportunity areas, using the criteria in Table 13.
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Table 13. Criteria in identification of primary opportunities for restoration
Criteria for Comments Primary Opportunity Proximity to existing wetland or Close proximity to existing habitat increases wildlife values, riparian habitat but has no effect on flood storage value. Proximity to river channel or to Close proximity to water source decreases costs/efforts open water necessary to provide water to wetland/riparian habitat projects and improves wildlife values. Within or adjacent to abandoned Abandoned oxbows have alluvial soils suitable for recharge and oxbow storage of flood waters. These sites are also attractive for wetland or riparian restoration due to grading and proximity to Evidence of surface flows Sites thatd naturally receive and concentrate runoff from flood or storm events may have a greater aptitude for establishment of the wetland hydrology necessary for wetland or riparian restoration .
This screening identified 482 acres of primary opportunity sites and 540 acres of secondary opportunity sites (Figure 18). Potential restoration areas were defined by aggregating the best primary and secondary opportunities into nine areas, named A through I (Figure 19).
Google Earth
Figure 18. Primary (red) and secondary (yellow) opportunity sites and designated Area A.
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Google Earth
Figure 19. Nine areas identified as best opportunities for ecosystem restoration
9.4 ER ALTERNATIVE SITE PLANS
Multiple alternative site plans were identified for these nine areas, with a minimum of two site plans per location, as illustrated in Figure 20 below. Measures combined for these site plans are those listed in Table 14. More details for all site plans which include aerials, existing habitat delineation and restored conditions are presented in Appendix E. There were 16 different existing conditions among these site plans, as the footprint for some alternatives at a given location varied slightly due to land ownership and land use constraints.
Figure 20. Example of site plan alternatives – Area A
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Table 14. Descriptive summary of alternative site plans Site Plans Restoration Description Acres A1 Place two rock weirs in the Cache la Poudre River to divert flows into an abandoned 21.03 meander which has become overgrown with undesirable vegetation (reed canary grass and cattails). The weirs would be set to an elevation that would divert flows at least once every two years. Emergent hydrophytic vegetation would be planted adjacent to and within the restored meander. Scrub-shrub wetlands would be planted next to the emergent wetlands and finally non-native trees would be removed and native trees would be planted. A2 This site plan eliminates the diversion structures proposed in A1 and would involve 21.03 grading the oxbow to an elevation that would allow hydrophytic plants to survive. Some benefits would be lost in the mink model as a result of some of the restored areas being too far from a water source. Similar emergent, scrub-shrub and forested habitats would be planted. A3 This site plan eliminates the diversion structures proposed in A1 and would involve 21.03 grading the oxbow to an elevation that would allow hydrophytic plants to survive. Within this wetland swale, five pockets of water would be excavated to provide benefits within the mink model. Similar emergent, scrub-shrub and forested habitats would be planted. A4 This site plan eliminates one of the proposed weirs in A1. One rock weir would be 21.03 placed to restore hydrology to the oxbow and would flow at least once every two years. Similar emergent, scrub-shrub and forested habitats would be planted. B1 Remove invasive plants and restore hydrology to historically wet areas. Plant native 63.74 emergent, scrub-shrub and riparian forest habitats. B2 This site plan plants more scrub-shrub species and less emergent wetland species 71.33 which adds more benefits to the yellow warbler model. Acreage difference is a result of expanding the restoration area footprint to encapsulate the Poudre River Trail at this location. C1 Remove invasive plants and restore hydrology to historically wet areas. Plant native 97.59 emergent, scrub-shrub and riparian forest habitats.
C2 This site plan is the same as C1; however, the footprint is smaller because the concept 79.25 is truncated at the county boundary line. D1 Remove invasive plants and restore hydrology to historically wet areas. Plant native 65.89 emergent, scrub-shrub and riparian forest habitats. Restore a historical waterway in the southeastern portion of the site plan location. D2 This site plan eliminates restoring the historical waterway, increases the amount of 65.89 scrub-shrub wetlands and reduces the amount of emergent wetlands. E1 Remove invasive plants and restore hydrology to historically wet areas. Plant native 26.92 emergent, scrub-shrub and riparian forest habitats. E2 This site plan decreases the amount of riparian forested areas, but increases the 25.75 amount of scrub-shrub wetlands. No emergent wetlands are proposed within this site plan. F1 Degrade several abandoned quarry walls to allow the river to enter these pits and then 29.1 continue through a channel until finally re-entering the river. Remove invasive plants and restore hydrology to historically wet areas. Plant native emergent, scrub-shrub and riparian forest habitats.
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Site Plans Restoration Description Acres F2 This site plan eliminates the notch and channel. Instead, an emergent wetland would 25.23 collect and convey water back to the river. Scrub-shrub wetlands and riparian forested habitat would also be planted. G1 Divert stormwater using a pump to convey water through a channel until reaching the 13.19 river. Both the former junkyard and trailer park were included within the restoration footprint. Remove invasive plants and restore hydrology to historically wet areas. Plant native emergent, scrub-shrub and riparian forest habitats. G2 This site plan would eliminate stormwater diversion; create emergent wetlands with 12.69 adjacent scrub-shrub wetlands and riparian forest species. Both the former junkyard and trailer park were included within the restoration footprint. Remove invasive plants and restore hydrology to historically wet areas. Plant native emergent, scrub- shrub and riparian forest habitats. G3 This site plan is very similar to G1; however, only restores the former junkyard site, 7.76 which means fewer acres. G4 This site plan is very similar to G2; however, only restores the former junkyard site, 7.5 which means fewer acres. G5 This site plan is very similar to G2; however, only restores the former trailer park, 5.5 which means fewer acres. H1 Place rock weir in the river to divert flows through a channel east of the railroad 16.58 tracks. Weir would be set to an elevation that would allow flow at least once every two years. Remove invasive plants and restore hydrology to historically wet areas. Plant native emergent, scrub-shrub and riparian forest habitats. H2 This site plan is very similar to H1; however, the rock weir and channel are eliminated 16.58 and replaced by a wetland swale. H3 This site plan eliminated the rock weir and channel. Stormwater is proposed to be 16.58 pumped from its current location through a wetland swale and eventually into the river. I1 Place rock weir in the river to divert water into the entire length (approximately 6,200 121.87 feet) of the abandoned oxbow. Weir would be set at an elevation that would allow flow at least once every two years. Remove invasive plants and restore hydrology to historically wet areas. Plant native emergent, scrub-shrub and riparian forest habitats. I2 Restore smaller portion (approximately 2,300 feet) of historical oxbow. Other habitat 121.87 restoration is similar to I1. I3 This site plan is very similar to I1 as the rock weir and channel restoration remain the 121.87 same. This site plan has much more excavation associated with creating scrub-shrub and emergent wetlands. I4 This site plan is very similar to I2 as the rock weir and channel restoration remain the 121.87 same. More riparian forested areas and less wetland is the main difference between I4 and I2.
Some of the 26 site plan alternatives were screened out before detailed evaluation. The four Corps of Engineers’ planning criteria - completeness, effectiveness, efficiency and acceptability - helped identify which measures to pursue. Examples of the application of the four criteria include:
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High Costs: Obvious high first costs may mean a plan is not efficient, not cost-effective, and this can eliminate some site plans. Low Benefits: Obvious low benefits may mean a plan is not effective, not worth pursuing. Non-effective: Some measures can be readily recognized as being inadequate, or not effective in addressing study objectives. Engineering Infeasibility: Technical impracticality indicates a plan is probably not effective or efficient. Low sustainability: Operation and maintenance requirements should not be unreasonably high and unsustainable. This would indicate an inefficient plan. Water Rights: These rights are fully appropriated, are costly to acquire, and may lead to litigation. This is a consideration for measures which would require water rights.
Area G site plans were screened out due to a determination that half the area could hold hazardous materials. It was previously used for a number of years as an automobile junkyard, and federal ecosystem restoration projects avoid using potential hazardous waste sites. Also, half of Area G would require very costly purchase of commercial property and relocation of multiple mobile home households. Several Area I site plans were screened out when it became obvious their costs would be disproportionately high. This left 18 site plans at 8 areas. All site plan concepts are described in Table 14.
9.5 ER ALTERNATIVE EVALUATIONS AND COMPARISONS
The 18 alternatives were evaluated using Habitat Evaluation Procedures (HEP) developed by USFWS. This multiplies the area of habitat by its quality, to provide a “Habitat Unit” (HU). The habitat quality is calculated using Habitat Suitability Index (HIS) models, for one or more indicator species. For this study, mink and yellow warbler were the riparian and wetland indicator species chosen, in cooperation with state and federal agencies, as these species’ needs include the desired federally-significant wetlands and riparian habitat; and HSI models were available for these species. HSI models for these species were approved in the 2008 CECW-CP Memorandum, and the modified mink model used here was approved on February 25, 2014. Use of these models for this study was approved by USFWS.
Suitability for mink is determined by water and cover conditions, so it is reflective of wetland values; it also reflects suitability for migratory birds and possibly some of the special status species. The yellow warbler model considers the quality of shrub and tree habitat near water, so it reflects habitat needs of a variety of migratory birds, as well as for some special status species. These models measure habitat quality in terms of vegetative cover, density, height of vegetation, and proximity to water.
Connectivity is a secondary objective and is partially evaluated by the above models, which measure the percent of an area having cover, and thus the proximity of habitat elements to one another within the area. Connectivity can also be evaluated by proximity of each area to the nearest available quality habitat, whether existing or restored.
For the study, the ecosystem restoration benefits are expressed in non-monetary terms as the net average annual equivalent habitat units (AAE HUs) over the 50-year period of analysis. Each
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site plan’s AAHUs were calculated as the average of the two species-specific AAHUs, for each target year (years 0, 1, 10, 25, and 50). These AAHU values for each site plan, along with the average annual cost for each site plan, were entered into the decision support software, Institute for Water Resources Planning Suite, Version 2.0.6.0 (IWR-Plan; USACE certified 22 September 2010). Costs included construction costs, value of land interests required, real estate administrative costs, construction engineering and design, construction management (supervision and administration), and contingencies. Costs were amortized over the 50-year period of analysis using a 3.5 percent interest rate (FY14 federal rate).
IWR-Plan generated alternative plans, through combining the site plans into every possible combination. Next, IWR Plan evaluated those alternative plans and identified the cost-effective plans; i.e., those plans which produce a given level of habitat output for the least cost. Plans producing the same amount of habitat for higher cost, or less habitat for the same cost, were eliminated. The cost-effective plans were then arranged in order of increasing output. Moving from one plan to the next higher output plan, the rise in cost is compared to the gain in output. Plans giving the largest gain in output for the least rise in cost are best buy plans. Of the 151 cost effective plans, CE/ICA identified 13 best buy plans, including the no-action alternative.
Using IWR-Plan an incremental cost analysis of the best buy alternative plans was completed. The best buy alternatives were arranged in order of increasing incremental cost per incremental output, as shown in Table 15 (as well as Figure 15). Alternative B2 (or Plan 1) is the first best buy plan and so it’s the most cost-efficient plan at providing environmental output. As shown in Table 15, moving from Plan 1 to Plan 8, each next best buy plan involves the addition of one additional restoration area, until all 8 sites are included in Alternative Plan 8. After this, each best buy plan involves the substitution of one site plan for an alternate site plan. This indicates that for the Greeley GI, restoring additional area is more cost-effective than spending more at one particular site.
Table 15. Best buy plans in order of outputs and costs INCREM. AA COST ALTERNATIVE BEST NET AA COSTS AA COST / INCREM. TOTAL FIRST Plan # BUY PLANS AAHUs ($1,000) / NET AAHU AAHU COSTS 0No Action 0$ -$ - $ - $ - 1 B2 43.4$ 140,380 $ 3,238 $ 3.24 $ 2,585,300 2 B2C1 109.0$ 389,990 $ 3,577 $ 3.80 $ 7,661,400 3 B2C1H2 121.7$ 458,340 $ 3,765 $ 5.39 $ 9,128,600 4 B2C1H2I4 190.6$ 856,390 $ 4,492 $ 5.78 $ 17,638,300 5 B2C1E1H2I4 203.1$ 928,590 $ 4,573 $ 5.82 $ 19,174,900 6 A2B2C1E1H2I4 213.4$ 991,450 $ 4,646 $ 6.06 $ 20,492,400 7 A2B2C1D2E1H2I4 241.3$ 1,191,450 $ 4,938 $ 7.46 $ 25,129,400 8* A2B2C1D2E1F2H2I4 259.8$ 1,373,850 $ 5,287 $ 9.41 $ 29,054,600 9 A2B2C1D2E2F2H2I4 263.3$ 1,412,810 $ 5,367 $ 11.40 $ 30,043,700 10 A2B2C1D2E2F2H1I4 263.5$ 1,416,490 $ 5,376 $ 15.74 $ 30,104,400 11 A4B2C1D2E2F2H1I4 263.5$ 1,417,650 $ 5,379 $ 22.04 $ 30,131,600 12 A4B2C1D2E2F1H1I4 265.6$ 1,704,900 $ 6,420 $ 141.30 $ 36,616,600 * NER Plan
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9.6 ER TENTATIVELY SELECTED PLAN / NATIONAL ECOSYSTEM RESTORATION (NER) PLAN
IWR-Plan plotted the incremental cost analysis for the best buy plans, as shown in Figure 15 below. Each added plan, from Plan 1 to the plan circled in red (Plan 8: A2B2C1D2E1F2H2I4), presents a rather uniform or gradual increase in incremental cost per incremental output for the first 8 alternative plans. All 8 restoration sites are included before one site plan is exchanged for a different site plan.
The appearance of all eight areas in the best combination demonstrates that, while habitat restoration can greatly improve an area, at some point it is more efficient to restore an additional area, rather than restore more habitat at the same area. This effect, which engages multiple areas cost efficiently, is also supportive of the objective to provide geographic connectivity within a proposed plan, and to improve the connection between the reaches upstream and downstream of the study area.
Figure 21. Incremental cost display of best buy plan combinations
Based on these analyses, the tentatively selected NER plan is Plan 8. This plan would increase riparian forest from 80 acres to 198 acres, and wetlands from 11 acres to 179 acres, as detailed in Table 16 and Figure 22. It would reduce acres of poor quality disturbed rangeland, other agricultural land, and disturbed areas an equivalent amount, approximately 286 acres.
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Table 16. Without project (WO) and with project (WP) habitat, year 50 Percent Acres Tree or shrub Deciduous Shoreline cover Hydrophytic Riparian Emergent Scrub-Shrub canopy w/in shrub crown w/in 1m of water shrubs Forest Wetland Wetland 100m of water cover WO 15% 22% 4% 75% 80.3 9.0 2.1 TOTAL WP 89% 93% 40% 92% 197.9 83.8 95.6 WO 35% 10% 8% 75% 6.4 1.1 1.0 A2 WP 90% 95% 38% 89% 11.2 5.6 4.2 WO 10% 20% 19% 75% 8.0 0.2 0.6 B2 WP 85% 95% 41% 93% 19.3 2.1 11.5 WO 5% 10% 1% 75% 5.6 0.7 0.0 C1 WP 75% 90% 60% 97% 25.7 36.1 35.8 WO 0% 50% 1% 75% 39.7 0.3 0.0 D2 WP 100% 95% 38% 92% 39.8 14.6 7.0 WO 8% 70% 2% 75% 1.9 0.5 0.4 E1 WP 90% 95% 18% 80% 19.3 4.8 2.9 WO 46% 5% 1% 75% 0.5 0.5 0.1 F2 WP 90% 95% 54% 98% 10.0 3.8 9.1 WO 1% 5% 1% 75% 0.0 0.1 0.0 H2 WP 90% 95% 38% 96% 8.1 4.9 3.7 WO 14% 5% 2% 75% 18.3 5.6 0.0 I4 WP 90% 85% 32% 88% 64.5 12.0 21.5
Figure 22. Bar graph of NER Plan change in acres of desired habitat types
10. RECREATION PLAN FORMULATION
Recreation features are an ancillary objective of Corps projects; they may be included, to a limited degree, in the context of a larger project for ecosystem restoration. Features and uses
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studied and proposed for this project would fit within relevant Corps policies (Engineer Regulation 1105-2-100 and Engineer Pamphlet 1165-2-1).
Recreation features and use would only be oriented toward ecosystem experience. Features and use would be compatible with and have minimal impact to the ecosystem restoration outputs. Recreation use would be day use only. The recreation measures would be drawn from among those listed in Corps guidance, Engineer Regulation 1105-2-100, E-49, Exhibit E-2. Features would be of basic or modest construction design, but durable. Recreation features would add no real estate requirements to the project beyond the ecosystem restoration area. BCRs would be greater than 1.0 for each recreation area. Recreation measures would be cost-shared 50-50 with the nonfederal sponsor. The federal share of recreation cost would not increase total federal costs more than 10 percent over the federal share of ER cost.
10.1 RECREATION GOALS AND OBJECTIVES
Goals for environmental-related recreation are to provide recreational benefits through access to the restoration areas in a manner that minimizes impact to the habitat and to inform visitors about the environmental value and significance of the habitat areas.
Objectives include: expanding upon the opportunities and experiences already provided by the existing Poudre River Trail providing nature-based recreation experience and interpretation at the ecosystem restoration areas protecting ecosystem resources and providing sustainable access by establishing formal paths and interpretive guidance
Access, intimate nature experience, and education are deemed important locally to engage the populace with the ecosystem and to develop a sense of ownership and stewardship, thus helping sustain and build upon the restoration work.
10.2 RECREATION OPPORTUNITIES AND MEASURES
Paved segments of the Poudre Trail are currently sited near and parallel to the boundaries of proposed ecosystem restoration areas A, B, C, D, E, and F, with 35,000-65,000 visits annually near Areas A, B, and C. The existence of this regional 22-mile trail provides an opportunity to develop trail linkages, connecting footpath trails proposed as part of the recreation alternative to the Poudre River Trail for Areas A, B, and C. Areas D and E are not good candidates for the recreation plan, because the Poudre River Trail and Greeley, is on the other side of the river and there is no existing access. Area F was excluded because the Poudre River Trail already abuts the southern boundary of this site, and this was deemed to be sufficient as the site is very linear. Areas H and I are currently undeveloped but on the same side of the Poudre River as Greeley; so
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proposed ecosystem restoration features would provide a new recreation opportunity for Areas H and I.
Figure 23. Alignment of Poudre River Trail near ecosystem restoration areas
The recreational features developed as part of the Corps recreation alternative are oriented towards providing trail access to the restored areas, compatible with the ecosystem restoration objectives. Trails within NER areas would be designed to minimize human disturbance to plant and animal communities, therefore soft-surface trails are planned. Trail experience would be enhanced and resource stewardship would be supported by adding interpretive signage along the trails. These features were considered for all areas A, B, C, H, and I. As noted above, there is currently not access to Areas H & I, so new trailhead facilities and a parking lot are considered for each of those sites. Simple shelters and sanitary features were considered appropriate at each of these trailheads. The trail alignments evaluated are shown in the figures below.
Figure 24. Proposed walking trails in Areas A, B, and C
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Figure 25. Proposed walking trails in Areas H and I
10.3 RECREATION PLAN DEVELOPMENT AND EVALUATION
The summary of proposed recreation features by area is shown in Table 17. Costs were developed for the proposed features, based on Greeley area costs for similar features, and estimated quantities needed for the proposed recreation plan, and are shown in Table 18. As shown in Table 18, total estimated cost for the proposed recreation plan is approximately $784,000 dollars.
Table 17. Summary of features by area Feature A B C H I Crusher fines trail X X X Packed earth trail X X X X X Boardwalk X X X X Signs X X X X X Parking Lot X X Trailhead X X X X X Notes: (1) Dollars in 2014$ (2) Cost estimates per feature do not include contingencies factored into total costs (3) Trailhead features include 2 shelters, 2 picnic tables, 2 benches, trash receptacles and sanitary toilets.
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Table 18. Recreation facilities cost estimate by area (FY2014) Item A B C H I Total Construction Cost $29,893 $51,550 $99,613 $81,457 $193,468 $455,982 E&D, S&A, Site Prep, and $20,626 $35,570 $68,733 $56,205 $133,493 $314,627 Contingency Estimated Total: $50,519 $87,120 $168,346 $137,663 $326,961 $770,609 IDC (1 yr, 3.5%): $880 $1,520 $2,930 $2,390 $5,690 $13,410 Investment Cost: $51,399 $88,640 $171,276 $140,053 $332,651 $784,019 Annualized $2,191 $3,779 $7,302 $5,971 $14,182 $33,426 Investment Cost: Annual OMRR&R: $2,563 $4,575 $8,790 $5,779 $11,415 $33,122 Total Annual Cost: $4,755 $8,354 $16,093 $11,750 $25,597 $66,548
As directed by the Planning Guidance Notebook (PGN) (ER 1105-2-100), recreation benefits are measured as the recreation users ‘willingness to pay’ for the recreation opportunity. Benefits of existing recreation opportunity (without project) are compared to the benefits of recreation under the with-project conditions. Based upon the criteria outlined in Figure E-10 in the PGN, Appendix E, the evaluation method selected for estimating recreation benefits is the unit day value (UDV) method.
The UDV calculation is based on two parts: an estimate of annual visitation and a value per visit. The visitor estimate was developed from existing data collected by the city of Greeley on Poudre River Trail usage. A survey of Poudre River Trail users was completed in 2009 and 2012, which determined the number of visitors to the Poudre River trail on a daily basis. Working closely with city of Greeley staff familiar with the Poudre River Trail survey data, estimates of visitor usage by recreation area were developed along with an estimate of the quality of the recreation experience both for the future-without and future-with project condition. The criteria published in the Economic Guidance Memorandum (EGM) 14-03, including: recreation experience, availability of opportunity, carrying capacity, accessibility and environment were the basis of the quality score estimate. Additional information about the UDV method and analysis is provided in the Recreation Appendix (Appendix G).
The results of the UDV estimate by restoration area, along with the estimated cost (total and annual) are provided in Table 19. The resulting benefit/cost ratios range from 44:1 at Area A and 24:1 at B, to approximately 5:1 at H. Because areas H and I would each include parking lots increasing the recreation cost, benefit/cost ratios are lower.
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Table 19. Summary of benefits and costs by area A B C H I Total Investment Cost: $51,399 $88,640 $171,276 $140,053 $332,651 Total Annual Cost: $4,755 $8,354 $16,093 $11,750 $25,597 $66,548 Annual Recreation Benefits: $211,069 $202,013 $155,830 $60,172 $157,629 $786,713 Benefit/Cost Ratio: 44.4 24.2 9.7 5.1 6.2 11.8 Notes: (1) Dollars in 2014$, (2) Total costs includes pre-construction engineering and design (PED), supervision and administration, and other contingencies.
The federal share of recreation cost, estimated at $386,000, would increase federal costs approximately 2.1 percent over the federal share of the ER cost, which is estimated at $18.4 million.
10.4 RECREATION Tentatively Selected Plan
The proposed recreation plan is: Area A: Nature trail, wetland boardwalk, interpretive signs, 2 benches near signs Area B: Nature trail, wetland boardwalk, 5 interpretive signs, 6 benches near signs Area C: Nature trail, wetland boardwalk, 3 interpretive signs, 3 benches near signs Area H: Trailhead parking lot, sanitary toilet, bollard, trash receptacle, nature trail, wetland boardwalk, 2 interpretive signs, 2 benches near signs Area I: Trailhead parking lot, gate, bollard, trash receptacles, sanitary toilet, 2 shelters, 2 picnic tables, nature trail, equestrian trail, wetland boardwalk, 6 interpretive signs, 6 benches near signs
Greeley’s experience has shown that public appreciation and use of trails is high. Greeley also found that the Poudre River Trail raised public interest in ecosystem resources and restoration, indicating that the proposed new features would be used and would further support ecosystem restoration.
In summary, increased access would further public understanding of nature and ecosystem restoration project. Signage would educate visitors and enhance their appreciation of the environment. The Poudre Learning Center could use the new access for nature education programs. Natural areas and access to them may generally contribute to quality of life in Greeley and appeal as a community.
11. DESCRIPTION OF TENTATIVELY SELECTED PLAN (PROPOSED ACTION)
11.1 PLAN COMPONENTS
The proposed flood risk management plan consists of nonstructural measures to minimize flood damages up to the 500-year flood event elevation, for cost-justified and owner-willing properties. The result will be added sustainability and economic viability to the area most affected. The proposed plan includes:
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Filling the basement of three houses and relocating basement utilities to main floor level. Elevating 40 houses in place by extending the foundation, filling the area below first floor, and relocating utilities. Buyout of one house located within the designated floodway, clearing the land and keeping it in flood compatible use. Dry and wet flood proofing 17 commercial buildings. Constructing a nonstructural floodwall around a group of three county buildings. Real estate required would consist of temporary rights of entry for construction, and temporary housing for residential occupants. Operations, maintenance, repair, replacement and rehabilitation (OMRR&R) responsibility with the city, performed in practice by property owners, with city oversight through permitting regulations.
The proposed ecosystem restoration plan consists of measures to restore wetlands and migratory bird habitat, increasing habitat connectivity, at eight areas totaling 446 acres. The proposed plan includes: Excavating and grading to detain precipitation and runoff, and to bring vegetation zones nearer to groundwater, in oxbows, swales, and other depressions. Planting and seeding herbaceous wetland plant communities within one meter of the river or other surface water. Planting woody wetland plant communities in proximity to the emergent communities. Planting woody riparian plant communities within 100 meters of the river or other surface water. Removing exotic plant species. Diverting river flows greater than two-year level into a historic river meander on one site. Real estate required would consist of fee title excluding mineral rights with restrictions on surface use, temporary work easements, and road easements for access. OMRR&R responsibility with the city.
The proposed recreation plan consists of basic measures at five restoration areas. Ancillary to ER provisions, recreation amenities will provide increased opportunity for people to reconnect, appreciate, and support important riparian corridor habitat, as well as contributing to quality of life aspects of the community. The proposed recreation plan includes: Crusher fines trails at areas B, C, and I. Packed earth trails at all areas. Boardwalk over wetlands at areas A, B, C, and H. Signs at all areas. Parking lots at areas H and I. Trailheads at all areas. No additional real estate interests required. OMRR&R responsibility with the city.
The combination of the NED Plan and the NER Plan with proposed recreation features (as shown in Figure 26) is both the federally-recommended plan and the sponsor’s preferred plan.
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Figure 26. All proposed FRM, ER, and recreation areas in the plan
11.2 PLAN FEASIBILITY
In the conduct of all Corps feasibility studies, alternative plans are formulated within the context of considering four fundamental planning criteria: completeness, effectiveness, efficiency and acceptability.
1. Completeness is the extent to which a given alternative plan provides and accounts for all necessary investments or other actions to ensure the realization of the planned effects. This may require relating the plan to other types of public or private plans if the other plans are crucial to realization of the contributions to the objective. 2. Effectiveness is the extent to which an alternative plan alleviates the specified problems and achieves the specified opportunities. 3. Efficiency is the extent to which an alternative plan is the most cost-effective means of alleviating the specified problems and realizing the specified opportunities, consistent with protecting the Nation’s environment. 4. Acceptability is the workability and viability of the alternative plan with respect to acceptance by state and local entities and the public and compatibility with existing laws, regulations and public policies.
Alternatives are compared based on contributions to these fundamental criteria in addition to how effectively each meets the planning objectives and whether or not they adhere to or violate the planning constraints. Table 20 summarizes the contributions the proposed plan makes towards the planning criteria, objectives, and constraints.
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Table 20. Comparison of proposed plan to planning criteria, objectives, and constraints INSTITUTIONAL PLANNING PLANNING PLANS COMPLETENESS EFFECTIVENESS EFFICIENCY ACCEPTABILITY OBJECTIVES CONSTRAINTS
NONE LOW 1. Ongoing flood risk is not 1. At risk properties remain at N/A LOW acceptable to Greeley. risk. Continued floodplain 1. Flood risk persists and 1. Flood risk remains and 2. Degraded environment and management could contribute increases over time. increases into the future. threat of future degradation NO to reduced risk through attrition 2. Natural areas continue to 2. Degraded ecosystem does not align with city goal of 1. No flood risk reduction, N/A over time. decline. remains and continues to increased open space and ecosystem improvement, or 1. No action proposed, no No Action 2. Ecosystem restoration not 3. Recreation continues to focus decline into the future. natural habitat areas. recreation experience in constraints applicable. likely to be implemented by on existing facilities and would 3. Recreation goals partially 3. Recreation development selected areas. others without federal lack quality of experiencing met with existing limited to existing facilities and assistance. restored native environmental facilities. does not fulfill city plans to 3. Recreation experience would habitats. improve recreational likely utilize existing facilities. experience. HIGH 1. 0.2% ACE level of risk reduction is acceptable to city HIGH of Greeley. 1. Proposed plan reduces flood HIGH 2. Proposed plan is compliant risks up to the 0.2% ACE flood 1. B/C ratio over 2.0. Only MODERATE with federal, state, and local YES event (500-year). structures individually cost- 1. Flood risks reduced for 64 of floodplain management 1. Reduces flood risks. 2. Residual risks abated through justified included in the N/A NED Plan 190 structures within the 0.2% regulations (> 1.0 foot above 2. Maximizes net economic floodplain management plan to proposed plan. ACE flood event (500-year). 1% ACE flood level). benefits. include flood warning, 2. 75% reduction in equivalent 3. No significant environmental evacuation routes, public annual damages. impacts under NEPA, no education and awareness. mitigation needed and full compliance with environmental laws.
HIGH YES 1. Proposed plan restores 446 HIGH 1. Proposed ecosystem restoration YES 1. Cost effectiveness / plan is acceptable to Greeley. 1. Restores hydrologic conditions MODERATE acres of riparian habitat: incremental cost analysis 2. Proposed plan is supported by improving habitat quality. 1. Ecosystem restoration on 446 emergent wetland acreage technique identifies the cost- federal, state, and local 2. Increases abundance and YES acres of 8,400. increased by 800% efficient best buy plans. resource agencies. diversity of riparian wetland 1. Proposed plan avoids airport NER Plan 2. Proposed plan strings together scrub-shrub wetland 2. The most cost-efficient 3. No significant environmental and woodland habitats. reach. restored habitat along a acreage increased by combination of best buy plans impact under NEPA, no 3. Increases connectivity within continuous 3-mile reach. 4,400% is selected as the proposed mitigation needed, full restored areas and along Cache riparian migratory bird plan. compliance with environmental la Poudre corridor. habitats acres by 146% laws.
YES HIGH HIGH 1. Improves recreation experience 1. Adjoins to existing regional 1. Very high B/C ratios (range MODERATE YES opportunities along existing trail at 3 sites increasing from 5.1 to 44.4 with net of 1. Provides recreation opportunity 1. Proposed recreation plan is regional trail. potential visitation and use. 11.8) due to significant demand in 5 of the 8 ecosystem areas. acceptable to Greeley. 2. Opportunities to interpret 2. Provides parking and new and proximity to existing N/A REC Plan 2. Provides linkage to existing 2. Proposed plan aligns with project restoration areas for access for recreation use at 2 regional trail. recreation trail and learning existing local recreation plans education and stewardship. isolated sites. 2. Incremental cost increase of center. for Greeley and Weld County. 3. Compliments restoration by 3. Provides multiple miles of soft $784,019 ($387 federal share raising visibility with minimal trails in 5 areas. or 2.1% increase) impact on ecosystem outputs.
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11.3 RISK MANAGEMENT
11.3.1 FRM Risk Management
11.3.1.1 Planning and design risk Planning and design risks include lack of detailed existing building design information for developing building-specific flood proofing costs for the buildings in the proposed plan. Assessor’s data, economic land-use inventory data, and exterior visual surveys were conducted for all residential and nonresidential structures. Standardized unit cost methodologies were used to estimate flood proofing costs based on these data. This methodology is standard practice and is considered to be an accurate method for determining residential foundation type, and nonresidential wall construction. Therefore, the type of house elevation, or nonresidential measures needed, was determined with low risk of error. Commercial building interiors are largely unknown, which is accounted for in the cost risk.
11.3.1.2 Hydrologic engineering risk Hydrologic risks include inaccurate data, inaccurate forecasts, and inaccurate modeling. The hydrologic analyses used stream gages with long periods of record and standard forecasting methods and approved models to minimize these risks. Accommodations for the risks were made in the uncertainties which were factored into the risk and uncertainty analysis.
11.3.1.3 Implementation risk Implementation risks include uncertainty as to which property owners would participate in the flood proofing since the plan would be voluntary. Variations in individual participation would affect both total costs and both total and net benefits accrued by the project. However, the overall plan would still be economically justified since each and every structure in the pool of eligible properties was economically justified by the plan, minimizing the financial consequence of this risk.
There is minimal risk that elevating residences would not be effective. There is a possibility that a few of the residences may not be amenable to the solution or that the solution would need to be customized due to occupants’ needs, such as addition of ramps for accessibility or site-specific adaptations for non-residential properties. This risk will be minimized during design phase investigations.
11.3.1.4 Cost risk Exterior dimensions for residential and non-residential buildings were available from public data or were estimated remotely as the basis for developing flood proofing costs. Non-residential interior floor plans, materials, and contents are not well known and may be more varied than for residential buildings which could affect final designs and costs. Detailed data for all properties will be collected during the design phase.
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11.3.1.5 Residual flood risk The proposed FRM plan would reduce flood risk for its eligible participants, without inducing flood risk on nonparticipating properties. Due to voluntary project participation, non- participating at-risk properties would remain at-risk during future flood events. The ineligible, economically-infeasible structures would also continue to be at-risk to future flood damages. However, the long warning times, relatively shallow depths, and low velocities of the flood waters would pose a low life safety risk. None of these risks are increased by the proposal, and could be further managed through implementing a comprehensive Floodplain Management Plan (FPMP) incorporating flood warning and designated evacuation routes.
The risk of potential project non-performance is considered very low. Non-performance for a nonstructural FRM project might include failure of flood proofing to keep water away from vulnerable property, failure of participants to place closure structures, or the unlikely failure of new foundations of elevated houses. Since these risks are distributed among each of the participating properties; one failure would not affect multiple properties and thus consequences would not be expected to be widespread.
A potential induced life safety risk would be that building occupants might be more tempted to shelter within a flood-proofed structure during a flood, rather than evacuate, due to an increased sense of security. Accessibility would be compromised in the event that a fire, injury, or illness required attention. Additionally, a major flood with elevations that rise above the level to which an individual structure was modified would result in some damages, however the damages would be greatly reduced from the without project condition. These residual risks could be addressed by warning and evacuation procedures within the FPMP.
General flood risks within the floodplain risk would continue to be managed through administration of floodplain management programs of Greeley and Weld County. Adoption and enforcement of city and county ordinances related to floodplain management and implementation of a FPMP would be responsibilities of the sponsor. The FPMP would be developed by the sponsor with guidance and assistance from the Corps. Floodplain regulations would be required to meet both federal (FEMA) and state of Colorado’s minimum standards in order for Greeley to maintain eligibility within the NFIP. The FPMP could expand outreach and education programs to communicate and maintain public awareness of flood risk and life safety actions to take in advance of flood events, and establish flood warning and emergency evacuation plans. The FPMP could also establish long-term planning objectives to increase conveyance at highway and railroad bridges to lower water surface profiles.
11.3.2 ER Risk Management
11.3.2.1 Planning and design risks Planning and design risks include some uncertainty regarding depths to groundwater which will support the wetland and riparian vegetation proposed in the plan. Groundwater can fluctuate annually and seasonally, but for planning purposes depths to groundwater were estimated based on observed water levels in existing nearby wetlands. Variation in the depth could affect Cache La Poudre River at Greeley, Colorado 66 Draft Feasibility Report and EA April 11, 2014
excavation quantities and costs, but would be covered by contingencies, and final design would verify this data element prior to construction.
11.3.2.2 Hydrologic engineering risk Hydrologic risks include inadequate groundwater information, inaccurate data, inaccurate forecasts, and inaccurate modeling. The hydrologic analyses used stream gages with long periods of record and standard forecasting methods and approved models to minimize these risks.
11.3.2.3 Implementation risk Implementation risks include uncertainty as to whether some of the real estate property required by the project may not become available. The sponsor has strong preference to implement the project on a “willing seller” basis for the real estate. The consequence of this risk would be limited to each individual area rather than the entire project, since each area is formulated functionally separable from the others
There is a low risk of encountering potential adverse site conditions which could impact implementation. An example is the possible presence of contaminated soils on a site, however, this risk is considered very low. Most of the areas are alluvial floodplain soils which have historically been used only for agricultural and recreational purposes. In a few instances, oil and gas well development could affect isolated portions of an area.
Maintenance risks include unforeseen maintenance requirements on ecosystem features that could result from high flows, erosion, sedimentation or other impacts. This risk is low due to the resiliency and self-sustainability aspects which will be incorporated into the final design of the ecosystem restoration features and rare frequency of severe floods which could cause substantial sedimentation.
11.3.2.4 Cost risk Preliminary designs and cost estimates were developed using detailed topographic mapping and best available data on groundwater and existing vegetation and soil conditions. Variation in the final geotechnical excavation quantities may vary with final design, but has been addressed through contingencies in the cost estimates. Detailed design data will be collected during the design phase.
11.4 DESIGN AND CONSTRUCTION CONSIDERATIONS
Participation in nonstructural FRM would be voluntary by owners. The project cost that would be provided for authorization assumes 100 percent participation.
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11.5 REAL ESTATE CONSIDERATIONS
11.5.1 Ownership and estates
11.5.1.1 FRM Real Estate Interests Real estate interests to be secured by the city for the FRM work include temporary work easements for all structures being worked on, and temporary lodging for most residence occupants.
11.5.1.2 ER Real Estate Interests The real estate interests proposed for ecosystem restoration would be standard Corps estates. Examples of the estates are included in Real Estate Appendix I.
Fee excluding minerals (with restriction on use of the surface), Temporary work area easement, and Road easement to develop access to the project areas where public access is lacking.
The primary estate would be fee title excluding minerals, with restriction on use of the surface. This recognizes that, in this area, mineral rights are typically severed from surface rights, and that the Corps project needs only surface rights. The sponsor would acquire surface rights for the designated footprints, adjusted for any uneconomic remnants or other needed variations. The estate would not allow surface access by mineral rights holders, therefore the sponsor would negotiate appropriate off-site access for mineral rights holders to develop minerals. Where the mineral rights were severed prior to sponsor acquisition, a separate subordination agreement will be required to restrict access to the surface and subordinate the mineral rights to the requirements of the ecosystem restoration. Sand and gravel are acquired and controlled as part of surface rights under Colorado law.
Greeley currently owns approximately 84 acres of the proposed 446-acre ER project area:
Area B 66.73 acres Area E 3.01 acres Area F 10.86 acres Area I 3.00 acres
Weld County owns approximately 80 acres of Area C, and 18 acres of Area F. The remainder is owned by private entities. The sponsor will be entitled to receive credit for the fair market value of the minimum estates identified for the construction, operation, and maintenance for the project.
No water right needs are anticipated for the project.
A preliminary land value was estimated for the lands proposed for inclusion in the ER project. The total value was approximately $8,561,659, including a contingency, for 446 acres. The Corps has prepared a gross appraisal and is currently reviewing it. The preliminary land value Cache La Poudre River at Greeley, Colorado 68 Draft Feasibility Report and EA April 11, 2014
estimates will be updated with the completed gross appraisal numbers at a later date. The gross appraisal is anticipated to come in at a value less than the preliminary estimate. The final land value that would be credited would be dependent upon the final footprint used, and upon further evaluation through a tract appraisal conducted by the sponsor and approved by the Corps.
No added real estate interests would be needed for the recreation component. 11.5.2 Hazardous substance review An Environmental Condition of Property survey will be conducted on all proposed properties.
11.6 OPERATION AND MAINTENANCE CONSIDERATIONS
FRM project OMRR&R would largely consist of maintaining the modifications to properties, in fully functional condition, for the life of the structures. For a residence buyout, the evacuated property would be maintained as open space or for recreation activities approved as compatible with flood risks.
ER project OMRR&R would include annual weed management, upkeep of beaver and deer protection for woody plants, fencing repair and replacement as needed, and repair and adjustment of the diversion weir as needed.
11.7 SUMMARY OF ENVIRONMENTAL AND SOCIAL EFFECTS (ENVIRONMENTAL EFFECTS)
Numerous alternatives were formulated to reduce flood risk and restore the riparian ecosystem. The nonstructural flood risk management plan is cost effective and is in the federal interest. The ecosystem restoration plan cost effectively restores resources of federal significance.
11.7.1 PRINCIPLES AND GUIDELINES ACCOUNTS
11.7.1.1 National Economic Development (NED) The study quantified benefits, costs, and net benefits for multiple FRM alternatives. The proposed nonstructural FRM plan would provide positive net benefits and the highest net economic benefits of all alternatives, and is the NED Plan. It would reduce equivalent annual damages by approximately 25 percent.
11.7.1.2 Regional Economic Development (RED) No substantial RED impacts of Greeley floods were identified in this study. Economic impacts are primarily local or have the potential to be replaced regionally within a reasonable time period. The proposed plan would nonetheless improve the ability of the regional economy to avoid impacts due to floods.
11.7.1.3 Environmental Quality (EQ) An EQ evaluation was done, including defining resources, inventorying and forecasting resource conditions, and assessing and evaluating effects on those resources. No significant adverse Cache La Poudre River at Greeley, Colorado 69 Draft Feasibility Report and EA April 11, 2014
effects would occur to significant EQ resources. Significant beneficial effects would occur to international migratory bird habitat and wetlands. These and other effects are described in Section 11.7.2 on environmental impacts.
11.7.1.4 Other Social Effects (OSE) Life safety would not be substantially affected. This study recognized that at least one community of mobile homes adjoins the river, posing a concern. Also, future urbanization in the county could increase risk of flash flooding along the river. However, the proposed plan, with accompanying emergency preparedness by the city, would not increase these risks and would not induce new risk to life safety.
The proposed FRM plan would have minimal effect on local emergency preparedness, long-term productivity, governmental fiscal condition, incomes, community character, population distribution and composition, stability, or cultural opportunities. It would provide flood risk reduction benefits to a substantial number of residents who are below average income and are primarily of minority ethnic origin. The proposed buyout of a house located in the floodway would displace one residential unit. The proposed ER plan would be a substantial financial commitment for the sponsor; the standard financial capability analysis required during feasibility studies will identify the sponsor’s financing plan. The proposed residential features would complement local plans and existing recreation features and would enhance community recreation experiences. 11.7.2 Environmental Impacts The following analysis pertains only to the no action alternative and the proposed action after dismissing all alternatives that were considered from undergoing detailed environmental consequences analysis because of rationale provided in earlier chapters.
This section separately addresses the FRM and ER components of the no action and preferred action alternative, and assesses potential impacts to resources described in Chapter 5.
11.7.2.1 FRM Non-Structural Plan Effects All of the structures that would be protected from nonstructural measures exist within the highly urbanized portions of Greeley, Colorado. Due to the lack of anything “natural” being present and all surroundings being modified for human use, the environmental consequences of all resources are described together in the following paragraphs.
No Action
No change to the geology, soils, fisheries, vegetation communities, wetlands, wildlife, federally- and state-listed species, land use, HTRW, air quality, noise, environmental justice, and hydrology would occur as a result of doing nothing to meet the purpose and need of the project. Essentially, the nonstructural measures are proposed in a highly urbanized environment where humans have already significantly altered the environment due to permanently converting natural riparian areas into residential, commercial and industrial properties. This existing permanent impact would likely not change if no project is undertaken to protect property from flood damage Cache La Poudre River at Greeley, Colorado 70 Draft Feasibility Report and EA April 11, 2014
and any threat to human life from flooding in the project area. However, the area most impacted by flooding is relatively poorer and with a higher minority population. Susceptibility to damage from flooding would continue to act marginally as a depressant on property values and economic activity in general.
No significant impacts would result from not doing anything to meet the purpose and need of the project as it relates to flood risk reduction.
Proposed Action
Implementing the nonstructural FRM measures would not have an impact on the geology, soils, fisheries, vegetation communities, wetlands, wildlife, federally- and state-listed species, land use, HTRW, and hydrology within the project area. This is primarily due to all work being done on impervious surfaces that are present due to the construction of residential and commercial buildings in the project area. The protection of structures by using nonstructural construction techniques would only mimic other construction activities that take place in the city on a daily basis. No natural habitat exists surrounding the properties proposed to be protected and any affect that measures taken to protect property and lives would not further degrade any resources or impact the quality of the human environment. The area most impacted by flooding is relatively poorer and with a higher minority population than Greeley or the state. Decreasing susceptibility to damage from flooding could only enhance property values, economic activity, and community sustainability and viability, thereby rendering some benefit in terms of environmental justice.
Any hazardous, toxic, radioactive, or otherwise controlled materials may eliminate an area or structure from inclusion in the final plan. Removal of any such materials from the property would be required before inclusion of the property. It is a project sponsor’s obligation to ensure all such materials are removed from sites before they are included. Asbestos, lead, and possibly other hazardous materials are assumed to be present in older structures. However, management of these materials would be handled by appropriate construction specifications.
Some minor and temporary impacts associated with construction machinery would occur through emissions from exhaust and noise associated with these machines. Weld County was designated as a non-attainment area for 8-hour ozone requirements in 2008; however, it has not recently exceeded these thresholds. The operation of work vehicles, generators, etc. that likely already are used daily in Weld County to complete construction work elsewhere would not negatively attribute to the overall air quality in Greeley. All construction would take place during regular work hours, Monday through Friday so impacts to noise levels should be negligible.
11.7.2.2 Ecosystem Restoration Effects The ecosystem restoration measures would be implemented in both urban and more rural areas. Therefore, the analysis of environmental consequences on individual resources (grouped together where logical) is broken out by resource below.
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Geology and Soils
No action Because no work would be completed, it is anticipated that no change to the geology of the area would occur under the no action alternative. Soils may be permanently disturbed and the surfaces may be converted into a future development if no action is taken to restore the proposed areas. Increased soil erosion may occur during the developments of these hypothetical projects.
Proposed action Excavation associated with the restoration of the NER plan would only disturb near surface soils and is not anticipated to have any effect on the geology of the project area. Soil disturbance would result from site clearing, excavation and restoration activities throughout the Project Area. None of the areas proposed to be restored are considered prime farmland because they are currently not irrigated. All of the ecosystem restoration areas involve some excavating to increase the ability of hydrophytes to persist on restored wetland areas through groundwater interaction or the collection and slow conveyance of precipitation and runoff back to the Cache la Poudre River. Excavated topsoil would be stockpiled and spread out and revegetated with native plants. Areas that included monocultures of cattails, purple loosestrife, reed canary grass, phragmites and other invasive species would have to have the topsoil through the root zone removed and disposed of offsite in order to successfully eradicate these species. Some topsoil may have to be hauled in if there isn’t at least 12 inches available from excavation at any given site.
There is the possibility as with any construction activity of spilling fuel, hydraulic fluid, or other unnatural materials. Care would be taken to inspect machinery, repair leaks and refuel at approved locations to minimize the likelihood of such accidents. A measurable loss in soil productivity and a contribution to air or water degradation would not occur as a result of implementing the proposed action.
Fisheries
No action It is anticipated if areas proposed for restoration are not restored than they may be susceptible to residential, commercial, agricultural or industrial development. Depending on the exact type of land use these areas develop into, especially locations A through E, increased impervious surfaces and hazardous fluids and other pollution associated with any development may enter the river and further degrade water quality. Some species that currently inhabit the river may not be able to tolerate these conditions.
Proposed action Most of the sites propose completing restoration above the top of banks of the Cache la Poudre River. Only one ecosystem restoration location (Location I) proposes to temporarily disturb the channel of the Cache la Poudre River. An approximate three-foot deep trench would have to be excavated from the river and approximately 200 linear feet of rock would be placed to create a weir at this location. The weir would be set to an elevation that would divert high river flows at
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least once every two years, which would restore hydrology to an abandoned oxbow. The physical construction of the weir is anticipated to take less than a day to complete. Impacts to the water column, substrate, turbidity and fish are not anticipated to be significant and would only be temporary in nature. It can be assumed that when high flows enter into the oxbow that fish would be present. These fish should have enough time to reenter the river as flows gradually decrease and return to only the main channel.
Although not specifically formulated for, some incidental increases in water quality would likely occur as a result of restoring riparian wetland habitats that filter nutrients from upland stormwater runoff through both rural and urban areas.
There is the possibility, as with any construction activity of spilling fuel, hydraulic fluid, or other unnatural materials, that they may drain into the river. Care would be taken to inspect machinery, repair leaks and refuel at approved locations to minimize the likelihood of such accidents.
Significant effects to fisheries as a result of implementing the proposed project are not expected.
Riparian habitat, vegetation and wetlands
No action If no action is taken to restore the prospective areas, it is likely that invasive and ruderal vegetation species will continue to out compete and take over these areas due to their ability to tolerate extreme variations in climate. Invasive and ruderal species provide little to no habitat value for wildlife that currently inhabit the areas. It is also anticipated if areas proposed for restoration are not restored than they may be susceptible to residential, commercial, agricultural or industrial development. An overall decrease in riparian habitat, vegetation and wetlands is likely to occur in order to facilitate this development.
Proposed action The purpose of the ecosystem restoration is to improve the riparian habitat within the study area through the primary means of removing noxious, invasive and non-native vegetation and restoring it to a more native natural condition by planting native species. This proposed project would increase riparian forest from 80 acres to 198 acres, and wetlands (both emergent and scrub-shrub) from 11 acres to 179 acres, as detailed in Table 16. It would reduce acres of ruderal rangeland, other agricultural land, and disturbed areas an equivalent amount by approximately 286 acres. The floristic quality and associated beneficial functions of wetlands, such as filtering pollutants, nutrients, pesticides, trapping sediment, and stabilizing soils would increase throughout the project area. Temporary impacts may occur to existing wetlands as excavation occurs to remove invasive species and grade to target elevations that are needed to provide adequate hydrology to support planted native hydrophytes. This work would be completed under Section 404 Nationwide Permit #27, which allows the Corps to complete ecosystem restoration work under certain regional and special conditions. The state of Colorado inherently certifies this action under its 401 water quality certification for all work completed under Nationwide Permits. No significant negative impacts to the riparian habitat, vegetation communities,
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including wetlands, are expected as a result of implementing the proposed ecosystem restoration project.
Wildlife
No action It is anticipated if areas proposed for restoration are not restored than they may be susceptible to residential, commercial, agricultural or industrial development. This would have the most negative impacts to wildlife in the non-developed proposed restoration locations A through E. If these areas were to be developed, the availability of any riparian habitat along the river within the project area would be reduced and wildlife would likely relocate to more suitable locations within the Front Range of the Rocky Mountains.
Proposed action One of the primary objectives of restoring the ecosystem at the proposed locations is to increase the availability of suitable habitat within the project area. Replacing invasive species with natives and planting more trees, shrubs and emergent vegetation will provide the habitat wildlife needs to forage, breed and rear their young. Temporary construction impacts to wildlife resulting from noise, disturbance and displacement would occur during excavating and planting activities. All construction activities would take place outside of nesting seasons of migratory birds in order to minimize any impacts to nesting birds. No significant negative impacts to wildlife would occur as a result of implementing the proposed action.
Federally- and State-Listed Species (Biological Assessment)
No action No federally-listed species are known to inhabit the project area and any effect, both positive and negative, are not anticipated. Several state species of concern are noted as potentially being present in the project area. Environmental consequences would be similar to those described under the wildlife no action heading above.
Proposed action No direct or indirect negative effects to federally and state threatened, endangered or state special concern species would result from implementing the ecosystem restoration project.
The Colorado butterfly plant and Ute ladies’-tresses can occur in habitats such as those found in the area. However, none were identified during field surveys of the area. Additional field surveys would be conducted by a qualified biologist prior to undertaking any construction. If these plants were observed, the USFWS would be contacted and no construction would occur until a resolution was reached which would not affect the species. Therefore, the proposed action would have no effect on these plant species.
The Preble’s meadow jumping mouse can be found in habitat such as that which occurs in the project area. However, no Preble’s jumping mice have been recently documented on the Cache la Poudre River within the study area. USFWS has concluded that the mouse has been extirpated
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from the project area. The Colorado National Heritage Program’s (CNHP) Biodiversity Tracking and Conservation System search has also identified the Preble’s meadow jumping mouse as known or likely to occur within the study area (CNHP, 2008). However, despite a number of trapping efforts, no mice have been recently documented on the Cache la Poudre River, between Fort Collins and the river’s confluence with the South Platte River east of Greeley (Armstrong, 1972). Therefore, the proposed action would have no effect on the Preble’s meadow jumping mouse.
Mexican spotted owls are not known or expected to occur in the area, although it is considered part of their historical range. If the owls were observed during preconstruction surveys, USFWS would be contacted and no construction would occur until a resolution was reached which would not affect the species. Therefore, no effect is anticipated.
The USFWS has identified additional listed species that should be considered in an effects analysis if specified conditions exist. The specified condition is when water-related activities could specifically affect depletion of flows to the Platte River. As the proposed project only diverts water at one location (I) on a very infrequent basis, no more than once every two years, and because it proposes to restore only historical wetlands, no effect is anticipated for the following Platte River species: pallid sturgeon (endangered), western prairie fringed orchid (threatened), interior least tern (endangered) and the piping plover (threatened).
Significance
The restoration of the scrub-shrub riparian habitat along the Cache la Poudre River may be vitally important and federally significant for the potential return of the extirpated Preble’s meadow jumping mouse. The draft recovery plan for the species indicates that the species was historically present in areas that have undergone extensive urbanization, but are currently absent (Ryon, 1996). Although the project area is not explicitly referenced in the plan, the conditions of extreme loss of suitable riparian habitat due to urban development is cited as rationale for the USFWS to clear historical ranges of the species in highly urbanized areas, such as: Denver, Adams and Arapahoe Counties (Compton & Hugie, 1993; Ryon, 1996). The USFWS refers to this as block clearance, which essentially means that due to loss of habitat, the USFWS believes the mouse is no longer likely to exist in these areas. This determination is caveated by stating that if they are found in these areas they would be fully protected under the ESA. The Cache la Poudre has several areas of critical habitat upstream of the project area, which means the mouse is present in the Cache la Poudre watershed where suitable habitat is available.
Completing the ecosystem restoration work described in the proposed action would contribute to providing connected habitat from the South Platte River to areas upstream of the project area. Restoration of riparian lands to emulate the natural habitat that once existed prior to urbanization may prove critical for the species to possibly return to its historical range as documented by the USFWS, which would be institutionally significant in support of the ESA. Additionally, the USFWS believes that the presence of invasive species contribute to the decline of the species, especially Russian olive (Selleck et al., 1962). The project proposes to remove these invasive
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species; therefore increasing the suitability of the restored riparian area to be suitable for the Preble’s meadow jumping mouse.
Land use
No action Land use for restoration sites F through I would likely remain the same if no restoration work is completed. Location I may be further developed for oil and gas use. Locations A through E are more natural areas than where the habitat has been degraded from modifications to the Cache la Poudre River and other anthropogenic disturbances. If no action is taken to restore these areas commercial, residential or industrial development may occur as the “open” areas are near Greeley and are located in a desirable setting next to the river. If left undeveloped, the existing vegetative communities would likely further degrade by the formation of monocultures of invasive vegetation.
Proposed action Implementing the restoration measures for locations A through E would restore these undeveloped areas and may prevent certain personal land uses with the exception of location B, which is already owned by Greeley. Location F is currently used as an equestrian park. This land use would be converted to a emergent wetlands, scrub-shrub wetlands and riparian forested area. Limited access would be provided on a trail that would abut the southern end of the site. Location H would be converted from fallow land dominated by ruderal species to more native vegetative communities. Location I’s current land use consists of industrial, including numerous oil and gas wells, and residential development. This use would change if the restoration work were completed by converting this parcel into a more natural area.
Environmental justice
No action Low-income, minorities or subsistence populations would experience no more adverse effects from the no action plan than any other human that may benefit from the restored areas. The universal impact would likely be the lack of being able to enjoy the restored areas. This may prevent all citizens from feeling connected to the river or caring about the riparian ecosystem.
Proposed action The human health or environmental effects to the residents in the proposed project area have not been identified to be disproportionately high or adverse on minority and low-income communities and Native American groups. The proposed action would not displace any residents. Although there are relatively low-income and high-minority populations in parts of Greeley, they would not be expected to be disproportionately affected by the proposed ER.
Cultural resources
No action
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No historic properties would be affected. One historic resource, the Greeley No. 3 Irrigation Ditch, is located near but separated by approximately 10 meters and a dirt road from the project area.
Proposed action This action in the wetlands would cause no affect to historic properties. There are no known archeological sites or historic structures within the project area. The project area soils are greatly disturbed due to natural (floods, river meanderings), and human (farming, borrow sites, and development) activities, therefore any historic properties that may have been there will not contain the necessary criteria for significance.
Air quality and noise
No action Air quality and noise would remain at current levels if no action is taken to restore the ecosystem within the project areas because the level of human activity is not influenced by the proposed action.
Proposed Action Some minor and temporary impacts associated with construction machinery would occur through emissions from exhaust and noise associated with these machines. Weld County was designated as a non-attainment area for 8-hour ozone requirements in 2008; however, it has not recently exceeded these thresholds. The temporary operation of construction machinery (scrapers, front- end loaders, all-terrain vehicles, trucks, etc.) would not negatively attribute to the overall air quality in Greeley. All construction would take place during regular work hours, Monday through Friday so impacts to noise levels should be negligible.
11.7.2.3 Environmental Statute Compliance Fish and Wildlife Coordination Act (FWCA) Discussions with USFWS under the provisions of the FWCA began in September 2011. Coordination included selection of a suitable habitat model and review of the application of the models. In a letter dated May 14, 2012, the USFWS states, “We support the application of HEP to the Greeley Project and consider the mink and yellow warbler HSI models appropriate choices to reflect habitat improvements.” On July 30, 2013, an email was sent to the USFWS to allow for considerations to resources within the project area. The USFWS responded on August 5, 2013 and stated due to funding and staffing issues, the agency was currently not reviewing impacts to any other resources for Corps projects that do not negatively affect threatened and endangered species.
Section 401, 402 and 404 of the Clean Water Act
Section 404 of the CWA governs the placement of dredged or fill material into waters of the United States. A majority of the restoration work would be completed above the OHWM of the Cache la Poudre. Only one alternative (I4) may place incidental material into the Cache la Cache La Poudre River at Greeley, Colorado 77 Draft Feasibility Report and EA April 11, 2014
Poudre (which is a waters of the U.S.), and this work would be authorized under Nationwide Permit (NWP) #27. NWP #27 is a Section 404 permit revised by the Corps every five years which authorizes work to restore aquatic ecosystems, if completed in accordance with the general and special conditions attached to it. Although not explicitly required when a project is completed using a NWP, an additional 404 (b) (1) analysis (Appendix E) was completed to document if any negative impacts to water resources would occur under the proposed action. A summary of findings is presented below.
No wetlands would be permanently negatively impacted. Some excavation of non-native species is expected to occur in order to plant natives at all locations. Placement of the rock weir proposed at Alternative I4 location would require excavating approximately three feet deep by 200 feet long on the bank of the river for the rock to be placed in. All excavated material would be disposed of at an upland site void of sensitive resources. The work would is anticipated to take less than a day and would occur during low flows which should prevent any material from entering the river. A very low probability of a temporary and minor effect on the aquatic food web and other fisheries and wildlife may occur as some soil may fall into the river while excavating the bank.
In the state of Colorado, Section 401 Water Quality Certifications are attached to any Nationwide Permit that a project is completed under. No additional permit application or documentation is needed to meet Section 401 requirements. Discharge of storm water resulting from construction activities that would disturb more than one acre of surface area requires a National Pollutant Discharge Elimination System permit under Section 402 of the CWA. A Stormwater Pollution Prevention Plan would be prepared prior to commencement of construction activities. The plan would address practices and measures required to control and reduce the amount of pollutants in storm water runoff.
Endangered Species Act The proposed project would have no effect on federally-listed species as described in Section 11.7.2.2.
Wild and Scenic Rivers Act Essentially, the Wild and Scenic Rivers Act protects and preserves wild and scenic rivers from development that would substantially change their wild or scenic nature. Portions of the Cache la Poudre River are designated as being wild and scenic; however, these areas are well upstream of the project area and start at the headwaters and end about eight miles west of Fort Collins. As such, no significant impacts would occur as a result of implementing the proposed action.
Clean Air Act Air quality in the Greeley area is “good,” which means for all pollutants measured the air quality index is less than 50. Air quality is projected to remain the same or degrade slightly due to increases in urbanization and associated commercial/industrial construction over the 50-year period of analysis. The proposed action and all alternatives would have minimal and temporary adverse effects on air quality, due to exhaust from mobile construction equipment, over a period of one year.
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Hazardous, Toxic, and Radioactive Waste Considerations A Level 1 Environmental Condition of Property survey will be conducted on all proposed ecosystem restoration areas, before completion of this study. Any hazardous, toxic, radioactive, or otherwise controlled materials may eliminate an area or structure from inclusion in the final plan. Removal of any such materials from the property would be required before inclusion of the property. It is a project sponsor’s obligation to ensure all such materials are removed from sites before they are included.
National Historic Preservation Act (NHPA) In compliance with the National Historic Preservation Act of 1966, as amended and all applicable regulations, the Corps conducted a review of the NRHP as well as information from the Colorado State Historic Preservation Office (SHPO) and Greeley Historic Register. Using information from the Greeley Historic Preservation Office, the Corps identified 54 recorded historic and cultural sites near the project area. The closest recorded site is the Greeley No. 3 Ditch, which has been determined to be eligible for listing on the NRHP.
Beginning in 1869, Greeley has produced numerous properties of local, state, and national historic significance. To date, within the Greeley area there are 17 individual properties and one district listed on the NRHP. The individual properties include churches, businesses, schools, courthouses and a historic downtown district. The Colorado State Register contains two individual properties and one district from the Greeley area. The Greeley Historic Register contains 85 properties. Of these 85 properties, 83 are individual properties and two are historic districts. The proposed project will not encroach on the Greeley No.3 Ditch, nor any recorded eligible or listed properties. In the proposed plan, the project footprint is separated from Greeley No.3 Ditch by a tow-track road, a minimum of ten meters.
The Corps is conducting a historical and architectural reconnaissance survey to identify any unrecorded eligible historic properties. Once complete, the Corps will contact the SHPO and provide an opportunity to comment on the project.
Noise Control Act According to EPA (2011), “the traditional definition of noise is ‘unwanted or disturbing sound’”. The units used in identifying noise are decibels (dB) on a logarithmic scale. Since human hearing is not equally sensitive to all sound frequencies, certain frequencies are given more “weight.” These frequencies for human hearing are measured on the A-weighted scale (dBA). The EPA has set values that should not be exceeded. While the primary responsibility of regulating noise was transferred from the EPA to state and local governments in 1981, the Noise Control Act of 1972 and the Quiet Communities Act of 1978 are still in effect. The EPA published its Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety in 1974 to provide state and local governments with information to develop their own ambient noise standards.
The construction of the proposed project would be conducted during typical working hours and is expected to cause temporary increases in ambient sound within and adjacent to the project area. The use of heavy equipment or trucks would be the primary noise source during
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construction and excavation. The level of impact would vary by equipment type, duration of construction activity and the distance between the noise source and the receptor. No significant impacts are expected to occur as a result of implementing the proposed action.
Bald and Golden Eagle Protection Act The National Bald Eagle Management Guidelines provide recommendations for avoiding disturbance to nesting sites consistent with the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. In this area, the nesting season runs from November 1st to July 31st. Accordingly, during this period, construction would avoid active nests by a maximum distance of 660 feet if the activity would be visible from the nest (USFWS, 2007b). A qualified biologist would coordinate with the USFWS Colorado Ecological Services Field Office in Denver, Colorado, to survey the area prior to clearing and construction efforts, as well as if a nest is suspected in the project area. No adverse impacts are anticipated.
Farmland Protection Act According to the U.S. Department of Agriculture (2014) area soils are poorly drained and may be considered prime farmland if they are drained, or protected from floods during the growing season, or irrigated. A CPA‐106 assessment was made for prime farmland presence, and no impact was determined. The form was sent on February 3, 2014 to the Natural Resources Conservation Service (NRCS), requesting concurrence. A representative of the NRCS responded, but the conversion worksheet calculations concluded that the project would not exceed any significant impact thresholds primarily because the soils within the project area are either not prime farmland or are prime farmland only if they are irrigated, which none of them appeared to be using 2013 aerial photography. A copy of the emails and the Farmland Conversion Worksheet are in Appendix E.
Executive Order 11988 Floodplain Management EO 11988, Floodplain Management Guidelines, May 24, 1977 outlines the responsibilities of federal agencies in the role of floodplain management. Each agency shall evaluate the potential effects of actions on floodplains and should avoid undertaking actions that directly or indirectly induce growth in the floodplain.
Flood profiles and floodplain boundaries were analyzed to determine if any negative impacts would occur within the proposed project area. The flood profiles provide a comparison of the water surface elevations, and the floodplain boundaries compare the extent of flooding for each flow. The FRM features will be in compliance because they do not change flood profiles or promote development in the flood hazard areas. The ecosystem restoration is to be designed such that it would not result in an increase in fill in the floodplain, and therefore would also be in compliance.
Migratory Bird Treaty Act The Migratory Bird Treaty Act (16 U.S.C. 703-712: Ch. 128 as amended) provides protection to migratory birds and prohibits the destruction of their active nests or nestlings. Construction activities that would otherwise result in the taking of migratory birds, eggs, young, and/or active nests should be avoided and be completed outside the primary nesting season. Cache La Poudre River at Greeley, Colorado 80 Draft Feasibility Report and EA April 11, 2014
The active nesting season for most migratory bird species in Colorado is between April 1st and August 15th, which coincides with the peak construction season. However, some birds are known to nest outside of the primary nesting period, and construction activities may occur any time of the year. Specific Colorado nesting seasons to consider include the bald eagle (November 1st – July 31st), cliff nesting raptors (February 1st – July 31st), burrowing owls (March 15th – October 31st), osprey (March 15th – September 10th) and ground nesting birds (May 1st – July 31st).
Care would be taken during construction to avoid any disruption to migratory birds. Clearing and grubbing would be scheduled to occur outside the primary nesting period, August 16th to March 31st. If construction of the project has to occur during the primary nesting season or at any other time that may result in the taking of nesting migratory birds, a qualified biologist would conduct a field survey of the affected habitats to determine the absence or presence of nesting migratory birds. Surveys would be conducted during the nesting season and immediately preceding the proposed construction activities. Should nests or nestlings of migratory birds be identified, construction activities would be modified to avoid disturbance and the USFWS Colorado Ecological Services Field Office in Denver, Colorado, would be contacted immediately for further guidance and assistance. If nests are active, activities that would directly impact the nest, or that would encroach close enough to cause adult birds to abandon the nest during the breeding season, would be restricted. No significant impact is anticipated, and the potential of an overall, long-term benefit to these species is anticipated.
The CPW recommends that any proposed destruction of prairie dog burrows be scheduled between November 1st and March 14th, in order to avoid impacts to the state-listed burrowing owl or that, if destruction of the burrows must occur between March 15th and October 31st, a protocol survey first be performed in order to ensure the absence of burrowing owls from the proposed grading/impacts (CPW, 2008).
Environmental Operating Principles (EOPS) The Corps has seven EOPs which are to be integrated in all Corps projects.
Strive to achieve environmental sustainability. Environmental sustainability will be advanced here by increasing the ability of the river corridor to perpetually inundate and form new habitat on flood plain lands, enabling plant community regeneration. Monitoring and adaptive management plans have been included to help achieve success.
Consider environmental consequences. This feasibility study has considered environmental consequences not only by proposing restoration of past habitat values, but also through National Environmental Policy Act (NEPA) evaluation of any potential adverse effects of the final array of alternatives. This report contains a complete integrated environmental assessment of the proposed action and primary alternatives.
Seek balance and synergy. The ER project would seek balance and synergy by restoring hydrologic connectivity between the river and its floodplain riparian community, so that
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it can interact beneficially with the riparian community. The FRM project would impose no structures in the floodplain that would change the characteristics of floods.
Accept responsibility. Accountability has been established by stating clear objectives to be met for each proposed project measure, by identifying the respective responsibilities of the Corps and the sponsor in this report, and by providing for monitoring and adaptive management which allow Corps action to ensure project success.
Mitigate impacts. Both the proposed ER and FRM projects have been formulated to require no formal mitigation. The ER project would instead improve environmental conditions at the site.
Understand the environment. Improved understanding of environmental and cultural conditions was obtained from coordinating with a variety of expert resources such as the USFWS, CPW, city of Greeley staff, and others. The proposed ER and recreation project would increase public understanding of the environment.
Respect others’ views. The study effort respected others’ views by inviting input from the general public and from affected agencies, and by incorporating to the extent feasible the input of those agencies and public who did provide input to this study.
11.7.2.4 Socioeconomics and Environmental Justice EO 12898 (Federal Actions to Address Environmental Justice in Minority Populations and Low- Income Populations) requires federal agencies to make achieving environmental justice part of its mission by identifying and addressing disproportionally high and adverse human health or environmental effects on minority and low-income populations. For this report, minority populations are defined as ethnic origins that include African Americans, American Indians or Alaska Natives, Asians, Hispanics or Latinos, and Native Hawaiian or other Pacific Islanders. Low-income populations are people living below the national poverty level.
The proposed project would not permanently displace any residents and would not disproportionately, adversely affect low-income, minority, or subsistence populations. In contrast, a low-income and minority population may benefit specifically from the FRM project; the residents of the primary FRM area are disproportionately from minority ethnic groups and have lower than average income.
11.7.2.5 Cumulative Effects Cumulative impacts are those that result from the added incremental effects of an action when taken in the context of the past, present and reasonably foreseeable future actions within a region. Cumulative impacts can result from individually minor but collectively significant actions taking place over a period of time. For this discussion, the cumulative impact assessment area (CIAA) includes the riparian area of the Cache la Poudre River from where it descends into the front range of the Rocky Mountains until it reaches its confluence with the South Platte River.
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Effects of Past and Present Land Use The dominant past and present land uses include farming, grazing, oil and gas development, rural and urban development, industrial operations and recreation. These uses have affected the following resources in the past or currently: soils, water resources, wetlands, threatened and endangered species, vegetation and invasive species, socioeconomics, wildlife, noise, cultural resources, and recreation.
Soils, vegetation and wetlands of the area have been disturbed by past and present farming, urban development and industrial operations (sand and gravel mining). These activities have lead to elimination or degradation of the riparian habitat by converting natural herbaceous, shrub and forested communities into farms, ranches, urban environments, oil wells and quarries. More specifically, farms and ranches remove native vegetation, drain wetlands, apply chemicals, contribute to pollution (manure) in the river and overall contribute to declines in water quality and habitat availability. The primary impact of urbanization is the conversion of natural vegetation communities to impervious surfaces. These impervious surfaces nearly abut the river and provide conduits for sources of urban pollution to directly enter the river because of the lack of any riparian vegetative buffer. By developing oil and gas wells within the CIAA, the risk of potential accidental releases of hazardous wastes increases and may cause environmental harm if an incident occurs. This effect is further exacerbated by the lack of riparian vegetative buffers that may prevent some pollution from entering the river. Sand and gravel mining contributes negatively to the availability and quality of riparian habitat. These mining operations typically locate next to rivers because the alluvium is most suitable to supply market demand. Excavating wetlands and other woody riparian habitat and replacing them with open water features does not provide the diversity of habitat needed to support the foraging, breeding and rearing young habitat desired by many species known to inhabit riparian areas within the CIAA.
Several, threatened and endangered species, including the Preble’s meadow jumping mouse, are identified to historically be present within the CIAA; however, none have been observed within the project areas. It can be assumed that the conversion of natural riparian habitats to urban areas and the consequential reduction of connected suitable habitat of riparian scrub shrub and emergent habitats along the Cache la Poudre, South Platte River, and other tributaries along the urbanized front range between Denver and Greeley is likely responsible for the extirpation of these species. This species still exists in these types of habitats both north and south of this extensively urbanized area.
The Cache la Poudre has been channelized within urban areas and water from it has been diverted to irrigate agricultural fields. These modifications coupled with agricultural, ranching, wastewater treatment, recreation (concrete trails located immediately adjacent to river), pollution (contaminated runoff in urban areas, trash and debris disposal) associated with urban environments have reduced the water quality of the river and the overall availability of suitable riparian habitat within the CIAA. A decline in the presence of native fish species is probably attributed to increases in water temperature, degradation of water quality, altered flow regimes, loss of spawning habitat and the presence of migration barriers (Davies, 2008). Riparian habitat is generally unavailable to wildlife within the urbanized areas due to the conversion of natural habitats to impervious surfaces and buildings. Agricultural use in rural areas has further
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fragmented suitable habitat by draining wetlands and removing native vegetation in order to plant crops. This has likely caused local population declines or shifts for some native wildlife and plant and animal species that prefer disturbed habitats.
Noise levels have risen commensurate with the level of farming, urban development and recreation within the CIAA, and encroached into what used to be relatively quiet riparian habitats. Socioeconomics have benefited from development activities and recreational opportunities in the area.
Although outside the CIAA, it should be noted that the Corps is involved in other restoration efforts that cumulatively improve the habitats within the front range of the Rocky Mountains. The Goose Creek restoration project in Boulder is restoring approximately one mile of wetlands and riparian habitat. Lower Boulder Creek in Boulder County will restore a meandering stream and riparian habitat for approximately one mile. These projects and others that may be proposed combined with the proposed action all have additive beneficial effects to the degraded riparian habits along rivers within the CIAA and beyond.
Effects of Reasonably Foreseeable Future Actions The types of land uses in the CIAA are expected to be similar in the future, but the levels of use may change. Urbanization, industrial operations and water supply are the most likely categories of development that would have the most effects on natural resources because they directly remove vegetation, increase the intensity and duration of human presence and permanently modify riparian habitat. The resources likely to be most affected by cumulative future land uses include water resources, vegetation and wildlife as a result of development that continues to encroach on more undisturbed riparian habitat. Farming, grazing, and the present level of rural, urban and industrial development are expected to stay at about the same growth levels, mostly restricted by the landforms of the area and the availability of land.
Projects under consideration by others would withdraw or store flows for municipal water supply and irrigation. Chief among these is the NISP and the accompanying reservoirs, which would intercept snowmelt near the mouth of the Poudre Canyon. The potential for the implementation of the NISP project upstream of Greeley would impact the natural flow regime along the Cache la Poudre River. In all proposed alternatives as listed in the April 2008 draft environmental impact statement (EIS) for NISP, water would be diverted from the Cache la Poudre. A reduction in peak flows could potentially lead to increased sedimentation within the study reach, which would in turn promote further colonization of non-native species and a reduction in natural riparian areas.
Greeley is in the process of building a 30-mile, 60-inch finished water transmission pipeline that will carry water from its Bellvue Filter Plant located northwest of Fort Collins to Greeley’s drinking water distribution system. The new pipeline will provide additional transmission capacity to Greeley’s existing system. The water transmitted by the 60-inch pipeline may include some water stocks that Greeley has historically treated at the Bellvue Filter Plant, as well as anticipated new water supply sources. These water sources include Cache la Poudre River water stored in a planned reservoir expansion, trans-mountain water from the Laramie and
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Colorado Rivers, and water from the north fork of the Cache la Poudre River. Some of these sources will require future water rights changes. Greeley is going to construct a wetland mitigation site as mitigation for wetland impacts resulting from the construction of the Bellvue pipeline project between ecosystem restoration areas “C” and “D.” While the wetland mitigation was created to offset impacts associated with the pipeline project, the context of the mitigation to restoration sites related to this project will be mutually beneficial by increasing total acres of habitat in the area and creating a more complexly connected corridor.
It is likely that gravel mining will continue within the project area, and that many gravel mines will be converted to water storage lakes following mining. It is not possible to accurately predict the specific location of gravel mines because the timing and location of the mining are subject to market forces. However, it can be confidently forecasted that the mining will continue to occur along the river because the alluvium of the river is gravel, which is the resource prospectors are looking to harvest. As such, these sites tend to be very impacting to riparian corridors because that is where they necessarily need to be. These sites are typically converted to water supply ponds also as a result of their relative position to the water source. Because of these factors, riparian corridors throughout the metro areas within the CIAA have been heavily denuded of riparian vegetation with a shift to fringe wetlands associated with open water sandpits. These habitats do provide some value, but have created a major shift in habitat types, leading to significant impacts to riparian corridors and the wildlife that inhabits them. Because there are so many species in Colorado reliant on riparian habitats, this has had a significant negative cumulative effect.
Recreation amenities including future trails, pedestrian bridges and interpretive signs would likely continue to be developed within the project area. Construction of these recreation features would depend primarily on land availability, funding, and community interest. Forecasting these three variables is difficult to predict; however, it is assumed that construction of these facilities would be designed to avoid any direct, indirect or cumulative effects on the resources being considered.
Effects of the Proposed Action Implementing both the nonstructural flood risk reduction measures and restoring the ecosystem within the project area are expected to have negligible negative cumulative effects on the human environment. Positive cumulative effects are anticipated. This assumption is based on the non- intrusive methodology to protect people and property from flood damages and inherent good that the ecosystem component proposes to do.
All of the flood risk reduction construction would take place in the urbanized portion of Greeley, where the natural resources affecting the quality of the human environment have already been degraded. Short-term and temporary effects associated with construction activities such as an increase in noise levels and air pollution from the movement of heavy equipment is not expected to be significant. Economic benefits would be realized by the reduction of the frequency of damages caused by flooding. Levees were looked at as alternatives to control flood damages for this project; however they are not being built in this project. Therefore, there should not be
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induced growth like often occurs within levee protected areas. The proposed action represents a responsible way to address flood risk along the Cache la Poudre.
The ecosystem restoration component would restore riparian and wetland habitat on 446 acres in eight areas along the Cache la Poudre River, over a distance of nine miles. Within the total acres available at all eight sights, the project would increase riparian forest from 80 acres to 198 acres, and wetlands from 11 acres to 179 acres, while reducing low quality rangeland and other land approximately 286 acres. The project would restore habitat that was previously lost as a result of the cumulative effects of the activities mentioned in this report. These restored habitats in and of themselves provide significant benefits to species that depend on riparian areas. Should additional restoration be pursued in this region, significantly more benefits would be expected, and potentially have synergistic effects.
Although threatened and endangered species are no longer found within the project area, restoring suitable habitat known to support these species along with other restoration work that may occur upstream within the CIAA may provide the opportunity for these species to return to areas within their historical range. Wildlife would likely receive direct, indirect and cumulative benefits from the increase in quantity and quality of riparian habitat within the project area and upstream through the CIAA. By removing invasive species and planting native species, the project would directly, indirectly, and cumulatively contribute to the increase in quality riparian habitat available for macroinvertebrates, flora and fauna that inhabit the CIAA.
Recreation features proposed to complement the ecosystem restoration locations would directly, indirectly and cumulatively benefit both the residents of Greeley and the CIAA. These new trails and interpretive signs would allow the community to directly interact with and develop a sense of responsibility for the Cache la Poudre, the riparian habitat and ultimately nature by allowing residents to experience and learn about the restored areas. Nature can provide a welcome refuge from the stresses of modern urban life, yet nature is getting farther away from where people live and recreate. The proposed amenities would allow those who live in an urbanized area a way to receive this refuge and improve their overall quality of life.
In summary, no negative cumulative impacts are anticipated as a result of implementing the flood risk reduction measures, ecosystem restoration components and recreation features described under the proposed action.
12. PLAN IMPLEMENTATION
12.1 INSTITUTIONAL, LEGAL, AND POLICY REQUIREMENTS AND ISSUES
Current authority is for the study only. Implementation of the proposed project would need further authorization and appropriations from Congress. Intervening steps toward specific authorization by Congress would include Corps approval of the project, and a Chief of Engineers Report to the Assistant Secretary of the Army for Civil Works (ASA/CW). Subsequently, Congress could pass authorization language, in legislation such as a Water Resources
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Development Act (WRDA). Congress could provide appropriation of federal Construction General funding in a fiscal year budget bill.
Alternatives to specific authorization for each component are discussed in the FRM Implementation and ER Implementation sections below.
Greeley through its City Council would need to approve the project for city sponsorship.
There are no other known obstacles to project implementation, within existing and expected local, state, regional, national, and international policies and regulations.
12.2 COSTS AND COST-SHARING
Tables 21 and 22 illustrate both the costs and the benefits of the proposed plan components.
Table 21. FRM project costs and accomplishments Economic Data – January 2014 Price Levels; 50-Year Project Life; Interest Rate = 0.035 (Excludes Feasibility Study Costs) $’000s Construction Cost $4,312 Engineering and Design $388 Construction Management $259 Contingencies for Above Items $942 Non-Federal Real Estate Acquisition, Admin., and Legal Costs (incl. contingencies) $229 Federal Real Estate Administrative/Legal Costs (incl. contingencies) $0 Interest During Construction $77 Total First Costs $5,902 Annualized Costs (50 years, 3.5% interest) $255 Annual Project Benefits $516 Net Annual Benefits $262 Annual Non-Federal OMRR&R Costs $0 Total Annual Economic Costs $322
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Table 22. ER and REC project costs and accomplishments Economic Data – January 2014 Price Levels; 50-Year Project Life; Interest Rate = 0.035 (Excludes Feasibility Study Costs) $‘000s Construction Cost $15,250 Engineering and Design $1,373 Construction Management $915 Contingencies for Above Items $3,508 Non-Federal Real Estate Acquisition, Admin., and Legal Costs (incl. contingencies) $8,677 Federal Real Estate Administrative/Legal Costs (incl. contingencies) $85 Interest During Construction $810 Total First Costs $29,807 Annualized Costs (50 years, 3.5% interest) $1,433 Annual Non-Federal OMRR&R Costs $107 Annualized Monitoring Costs $28 Net Average Annual Habitat Units (Net AAHUs) 260 Cost/Net AAHU $5.5 Recreation Annual Net Benefits $787
The fully funded estimate (Tables 23 and 24) for the selected plan includes price escalation using Office of Management and Budget inflation factors. A contingency was used. Economic cost data, which comprised the costs used in the CE/ICA and which include interest during construction (IDC; an economic cost but not a financial cost included in cost sharing) are shown in Table 24. Table 23. FRM fully funded estimate
PROJECT FIRST COST Civil Works Work Breakdown Structure ESTIMATED COST TOTAL PROJECT COST (FULLY FUNDED) (Constant Dollar Basis)
Program Year (Budget EC): 2014 Effective Price Level Date: 1 OCT 13 Spent Thru: WBS Civil Works COST CNTG CNTG TOTAL ESC COST CNTG TOTAL 1-Oct-11 COST CNTG FULL NUMBER Feature & Sub-Feature Description ($K) ($K) (%) ($K) (%) ($K) ($K) ($K) ($K) ($K) ($K) ($K) ABCDEFGHIJKLMNO
06 FISH & WILDLIFE FACILITIES $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0 14 RECREATION FACILITIES $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0 19 BUILDINGS, GROUNDS & UTILITIES $2,811 $562 20% $3,373 0.0% $2,811 $562 $3,373 $0 $2,990 $598 $3,588 19 BUILDINGS, GROUNDS & UTILITIES $1,286 $257 20% $1,543 0.0% $1,286 $257 $1,543 $0 $1,368 $274 $1,642 02 RELOCATIONS $215 $0 0% $215 0.0% $215 $0 $215 $0 $229 $0 $229 ______CONSTRUCTION ESTIMATE TOTALS: $4,312 $819 $5,132 0.0% $4,312 $819 $5,132 $0 $4,587 $872 $5,459
01 LANDS AND DAMAGES $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0
30 PLANNING, ENGINEERING & DESIGN $388 $74 19% $462 0.0% $388 $74 $462 $2,611 $435 $83 $3,128
31 CONSTRUCTION MANAGEMENT $259 $49 19% $308 0.0% $259 $49 $308 $0 $275 $52 $328
PROJECT COST TOTALS: $4,959 $942 19% $5,902 $4,959 $942 $5,902 $2,611 $5,297 $1,007 $8,915
CHIEF, COST ENGINEERING, xxx ESTIMATED FEDERAL COST: 65% $5,795 PROJECT MANAGER, xxx ESTIMATED NON-FEDERAL COST: 35% $3,120
CHIEF, REAL ESTATE, xxx ESTIMATED TOTAL PROJECT COST: $8,915
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Table 24. ER and REC fully funded estimate
PROJECT FIRST COST Civil Works Work Breakdown Structure ESTIMATED COST TOTAL PROJECT COST (FULLY FUNDED) (Constant Dollar Basis)
Program Year (Budget EC): 2014 Effective Price Level Date: 1 OCT 13 Spent Thru: WBS Civil Works COST CNTG CNTG TOTAL ESC COST CNTG TOTAL 1-Oct-11 COST CNTG FULL NUMBER Feature & Sub-Feature Description ($K) ($K) (%) ($K) (%) ($K) ($K) ($K) ($K) ($K) ($K) ($K) ABCDEFGHIJKLMNO
06 FISH & WILDLIFE FACILITIES $14,608 $2,922 20% $17,530 0.0% $14,608 $2,922 $17,530 $0 $15,613 $3,123 $18,735 14 RECREATION FACILITIES $642 $128 20% $770 0.0% $642 $128 $770 $0 $693 $139 $831 19 BUILDINGS, GROUNDS & UTILITIES $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0 19 BUILDINGS, GROUNDS & UTILITIES $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0 02 RELOCATIONS $0 $0 - $0 - $0 $0 $0 $0 $0 $0 $0 ______CONSTRUCTION ESTIMATE TOTALS: $15,250 $3,050 $18,300 0.0% $15,250 $3,050 $18,300 $0 $16,305 $3,261 $19,566
01 LANDS AND DAMAGES $8,762 $0 0% $8,762 0.0% $8,762 $0 $8,762 $0 $8,680 $0 $8,680
30 PLANNING, ENGINEERING & DESIGN $1,373 $275 20% $1,648 0.0% $1,373 $275 $1,648 $0 $1,588 $318 $1,906
31 CONSTRUCTION MANAGEMENT $915 $183 20% $1,098 0.0% $915 $183 $1,098 $0 $977 $195 $1,173
PROJECT COST TOTALS: $26,300 $3,508 13% $29,807 $26,300 $3,508 $29,807 $0 $27,551 $3,774 $31,325
CHIEF, COST ENGINEERING, xxx ESTIMATED FEDERAL COST: 65% $20,361 PROJECT MANAGER, xxx ESTIMATED NON-FEDERAL COST: 35% $10,964
CHIEF, REAL ESTATE, xxx ESTIMATED TOTAL PROJECT COST: $31,325
The total project design and implementation cost would be shared between the Corps and the local sponsor, according to the cost-share rates specified in law for each project purpose, as shown in Table 25 below. The federal share of FRM and ER costs is 65 percent, and 50 percent for recreation.
Table 25. Total estimated project costs and cost shares Sponsor Ratio TOTAL Federal Total Implem'n LERRD Cash OMRR&R Flood Risk Management 65:35$ 5,869,000 $ 3,815,000 $ 2,054,000 $ 624,506 $ 1,429,494 $ - Ecosystem restoration 65:35$ 29,028,000 $ 18,868,000 $ 10,160,000 $ 8,564,000 $ 1,596,000 $ 107,000 Recreation 50:50$ 771,000 $ 386,000 $ 386,000 $ - $ 386,000 $ 11,400 TOTAL $ 35,668,000 $ 23,069,000 $ 12,600,000 $ 9,188,506 $ 3,411,494 $ 118,400
12.3 DIVISION OF PLAN RESPONSIBILITIES
This feasibility study phase is cost-shared 50-50 between the Corps and Greeley as the non- federal study sponsor. Study cost-sharing accounts will be balanced and closed at the end of the study.
Before the conclusion of this study, Greeley, as the intended implementation sponsor, would provide a Letter of Intent to accompany the final feasibility report, expressing support for the recommended project, and attesting that it is ready, willing, and able to sponsor the project, including providing all LERRDs necessary for the recommended project. Greeley would also sign a Statement of Financial Capability, stating that it is aware of the financial obligations of sponsorship for the project and would have the financial capability to satisfy those obligations in accordance with the project funding schedule. Greeley would submit to the Corps a Financing Plan, describing how it plans to meet its financial obligations for the project in accordance with Cache La Poudre River at Greeley, Colorado 89 Draft Feasibility Report and EA April 11, 2014
the project funding and OMRR&R schedules. Greeley would also provide the Corps a summary of the pertinent statues and laws prepared by its attorney, which describes the City's authority to act as a sponsor.
The Corps would prepare all design plans and specifications, with potential work in-kind by the sponsor. Preconstruction Engineering and Design (PED) would be cost-shared 65% federal, 35% non-federal until the point at which the project is authorized by Congress and a Project Partnership Agreement (PPA) is executed. The PPA would identify cost-sharing requirements for the remainder of design and construction of the project in accordance with cost-sharing percentage based on project purposes.
The sponsor would provide all needed real estate interests, which would be credited at fair market value, toward the sponsor share of implementation costs. The sponsor would retain the ecosystem restoration and recreation land interests in public ownership in perpetuity for project purposes. The sponsor would not need to retain any permanent real estate interests for the FRM component; however, the sponsor would need to ensure that the buyout parcel remained in a use compatible with flooding, such as ecosystem purposes or appropriate recreation use.
The Corps would advertise the construction contract, most likely using full and open invitation for bids. The Corps would supervise all construction; except that portions of the construction could be performed by the sponsor as work-in-kind, credited toward its cost share, if specified in the PPA and preapproved by the Corps.
The non-federal sponsor would also be responsible for OMRR&R of the project after completion.
12.4 FRM IMPLEMENTATION
The Corps is recommending that the FRM component of the project be moved into the Section 205 Program for design and implementation. Greeley is supportive of this approach. The transition could occur after the completion of the concurrent reviews of this draft report, but a final decision on timing of when to convert has not been made.
The Section 205 Program refers to Section 205 of the Flood Control Act of 1948, as amended, which is a Corps Continuing Authority Program for local flood risk management projects. Section 205 was established to provide for streamlined implementation of relatively small, non- complex flood risk management projects that meet economic feasibility and federal interest criteria. Section 205 projects are limited to a maximum federal share of $7 million which equates to approximately $10.8 million total project cost (based on 65/35 cost sharing). The estimated cost of the FRM component would fit within the Section 205 authorized project cost limits, and transitioning to that program would negate the need for a Chief of Engineer’s Report and future specific authorization by Congress. Cost-sharing rates and sponsorship requirements would remain unchanged.
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When a flood risk reduction project is brought to construction, a floodplain management plan, as required by Section 202 of WRDA 1996, is developed to assure that the integrity of the federal project will not be diminished during its life and that impacts of future flood events in the project area have been reduced. A FPMP for a feasible, selected alternative would be developed when a flood damage reduction project is approved and the project plans and specifications are being developed.
12.5 ER IMPLEMENTATION
The ER component of the project would be carried through approval by the Chief of Engineers and provided to Congress for consideration for specific authorization through a future WRDA. Following approval of the Chief’s Report, the Corps would consider budgeting for PED to complete design plans and specifications for the first increment of construction. Upon authorization and appropriation a PPA would be executed and construction would commence.
12.5.1 Monitoring and Adaptive Management It is a Corps requirement that ecosystem restoration projects include monitoring, for assessing performance and determining whether adaptive management is needed to attain project benefits. Monitoring would be used by Omaha District in consultation with the sponsor, federal and state agencies, and the Corps’ division office to determine any changes (adaptive management) that may be needed. Changes would need concurrence from the sponsor and would be cost shared with the sponsor. Monitoring and adaptive management are not the same as inspections or operation and maintenance, for which the sponsor would be responsible even during the monitoring period.
Monitoring sampling would occur at least twice annually for up to five years and would include hydrologic monitoring and vegetation monitoring. Monitoring is estimated to cost $28,000 per year for the monitoring period. This is part of the total project cost shared between the Corps and the sponsor. Implementation responsibilities for the monitoring plan will be identified in the PPA.
Metrics are the success criteria described earlier.
o Percent of area canopy cover within 100 meters of water: 75 percent is optimal. o Percent cover within one meter of shoreline: At least 75 percent. o Suitable hydrology: Wetlands meet at least temporarily flooded standard. o Percent native hydrophytes: At least 50 percent. o Measure areas of suitable habitat and distances between: Use a Global Positioning System to measure communities. o Floristic quality index: At least 6.0. o Species diversity: Shannon-Wiener Index value greater than 2.5.
The adaptive management (contingency) plan assumes potential minor project adjustments to improve project performance and ensure habitat outputs are achieved in accordance with the
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proposed plan. Adaptive management adjustments are expected to be minor based on the moderate scale of the project. If the metrics outlined above are not being met, then the following modifications would likely need to be implemented in order to allow the restoration areas increased chances of ecological success. The nature and cost of potential adjustment measures are described below and are encompassed within contingency costs used for the plan.
Replanting failed vegetation, approximately 1/8 of the total, at a cost of $181,798. Modification of diversion structure, equivalent to roughly half the construction amount, or approximately $15,537. Excavating and re-planting to modify deficient hydrology, at a cost of $475,654. Vegetation management techniques, such as mowing, haying, flattening, grazing, or burning, at an estimated cost of $635,086.
Corps project closeout would occur four to five years after completion of construction, under the expected scenario that monitoring indicates that ecological success had been reasonably achieved.
12.6 RECREATION PLAN IMPLEMENTATION
Recreation features would be ancillary to an ecosystem restoration project. Thus, their authorization and funding path would be the same followed by the ER Plan.
12.7 OPERATION, MAINTENANCE, REPAIR, REPLACEMENT, AND REHABILITATION
OMRR&R of the completed project is the responsibility of the sponsor. These activities are not the monitoring and adaptive management described for ER work. Operation is the control of constructed features whose regulation or other manipulation is intended and necessary to ensure the project’s performance. Maintenance is those activities of a routine nature that hold the project in a well-kept condition, to keep it functioning as intended, and to defer more damaging or costly repair or replacement needs. Repair is the resolution of unexpected failures and problems as they arise. Replacement covers those activities taken when a worn-out element or portion thereof is replaced. Rehabilitation refers to activities necessary to bring a deteriorated project back to its original condition. Repair, replacement and rehabilitation actions are to conform to the project as-built plans and specifications unless other arrangements are made with the Omaha District Commander.
When the Corps determines that the entire project or a functional portion of the project is complete except for monitoring, the Corps will notify Greeley. From that time, the non-federal sponsor will operate, maintain, repair, rehabilitate, and replace the project in accordance with the PPA. The Corps will furnish Greeley with an OMRR&R Manual and with any as-built drawings.
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For FRM, OMRR&R would include periodic inspections and reporting, and regulatory control over structure modifications. For ER, it would include occasional structure maintenance, invasive weed control, and periodic inspections and reporting. For recreation, it would include the trails, sanitary feature, shelters, signage, and parking lots.
The city as sponsor would be responsible for FRM project OMRR&R. In practice, however, it is expected that property owners would bear responsibility for the actual maintenance of the structure modifications. City activity would consist primarily of regulatory oversight to ensure property compliance.
The sponsor would be responsible for OMRR&R of ecosystem restoration features. This would include annual weed management for such species as Canada thistle, teasel, Russian olive, crack willow, and reed canary grass. It would include maintaining the protection of plantings from beaver and deer, for a number of years. It includes some fence replacement and repair over the economic life of the project. The rock weir in I2 would require occasional refurbishment due to any settling or wear or movement of the rock. Annual inspections and reports would be required. Total OMRR&R cost is estimated at $107,000 annually for the eight areas.
12.8 SCHEDULE
The proposed schedule for completion of this study, and future implementation, is shown in Table 26. FRM construction is scheduled to last one year. ER construction is scheduled to last 1.5 years.
Table 26. Proposed schedule for Greeley GI study completion
12/30/2014 Corps Chief’s Report 6/1/2015 Congressional authorization 10/1/2016 PED $ rcvd 10/1/2017 Construction starts 10/1/2018 FRM Construction ends 4/1/2019 ENR Construction ends
13. COORDINATION, PUBLIC AND AGENCY VIEWS & COMMENTS
Public involvement occurred in the reconnaissance phase, as coordination meetings with the city, various resource agencies, and other stakeholders. A summary of that public involvement is presented in the Corps’ reconnaissance report (USACE, 2004). Further public involvement meetings were held over the course of the feasibility study. Some meetings were of a general informational format and others were more specific outreach to stakeholders, as described below.
Meetings with the Poudre River Advisory Committee began in April of 2006. This group was formed during the reconnaissance phase to provide input to the study to provide a public forum for discussing the study. Additional meetings with this group were held in September 2006, May 2008, December 2008, and May 2010, and agencies, landowners, business owners, and others were included. These meetings addressed problems, opportunities, and ideas for solutions. Cache La Poudre River at Greeley, Colorado 93 Draft Feasibility Report and EA April 11, 2014
Websites were established to provide information, including project documents for download to the general public and to agencies. The Omaha web page is at: http://www.nwo.usace.army.mil/Missions/CivilWorks/Planning/EnvironmentalPlanning/DraftDo cuments.aspx
Greeley has established a robust body of information on its website.
http://www.greeleygov.com/Engineering/CacheLaPoudre.aspx
The Corps and city officials met with gravel pit operators in September 2008. Gravel pit operators and representatives were concerned about the impact of the project on current and future gravel mining operations. They explained the commercial, residential, and water right values of gravel pits, but also indicated a willingness to work with the ecosystem restoration goals of the project. The study later determined that the reach with most gravel pits should be avoided, due to the multiple competing plans and developments underway at that location.
A formal public involvement meeting was held in December 2008. Advertisements were placed in both English speaking and Spanish language media. Bilingual PowerPoint presentations and handouts were provided, and an interpreter was engaged. Discussions at the meeting covered flood risk reduction, tributary flooding, the constriction at the sewage Treatment Plant and Fern Avenue, real estate issues, flood storage in gravel pits, the need for FAA coordination, and plans for channel sediment removal.
Federal and state agencies, including those with environmental regulatory and planning authority, participated in the Poudre River Advisory Committee meetings, as well as interested non-governmental organizations (NGOs). Agencies represented at Advisory Committee Meetings in the feasibility study phase included the USFWS, CPW, Colorado Water Conservation Board and Poudre River Trail Corridor, Inc. State and local agencies and environmental NGOs are strong proponents of the GI study and its efforts to improve the riparian ecosystem.
An interagency meeting was also held in December 2008. The meeting was well attended, participation was active, and the general consensus was support for the GI study. In addition to those agencies already serving on the Poudre River Advisory Council, agencies in attendance included the CNHP (Colorado State University) and the Poudre Learning Center.
Public, agency, and other stakeholder meetings will be held during the review phase of this draft feasibility report.
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14. QUALITY REVIEWS
The study has completed multiple Corps reviews and is scheduled to complete several additional reviews (Table 27).
Table 27. Quality and vertical team reviews Date Review PAST Agency Technical Review (ATR) for July 2009 Feasibility Scoping Meeting Feasibility Scoping Meeting March 2010 In Progress Reviews (IPRs) Sept. & Dec. 2013 Value Engineering Jan. 2014 Pre-Tentatively Selected Plan (TSP) IPR Jan. 2014 TSP March 2014 PENDING Draft Report Reviews Concurrent: ATR, Independent External Peer Review, & Ongoing April 2014 Legal, Public, & Agency reviews
15. RECOMMENDATIONS
A thorough feasibility study has been conducted regarding flood risk management, ecosystem restoration, and recreation opportunities along the Cache la Poudre River at Greeley, Colorado. Justified plans have been identified which would provide benefits in the federal interest including nonstructural flood risk reduction and improvements to riparian and wetland habitats benefitting international migratory birds and native species, with ancillary recreation features. The proposed flood risk management plan would modify 44 residential and 20 nonresidential structures to reduce flood risks up to the 0.2 percent ACE (500-year) flood elevation. It would elevate 40 of the residential houses in place, fill basements in three other houses, and buy out one residence located in the designated floodway. It would dry flood proof and wet flood proof 17 commercial structures, and place a floodwall around a group of three Weld County buildings. The ecosystem restoration component would restore riparian and wetland habitat benefitting 446 acres in eight areas along the Cache la Poudre River, over a distance of nine miles. It would increase riparian forest from 80 acres to 198 acres, and wetlands from 11 acres to 179 acres, while reducing low quality rangeland and other land approximately 286 acres. Recreation features ancillary to the ecosystem restoration component would complement five of the eight restoration areas by providing roughly seven miles of trails, ½-mile of wetland boardwalk, two trailheads with parking lots, shelters, and signage.
I have given consideration to all significant aspects in the overall public interest. Aspects considered include environmental, social, and economic effects; engineering feasibility; the unique capabilities and strengths of the Corps to study, design, and implement such a project; capabilities and interests of the cost-share sponsor; and other elements. The non-Federal
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sponsor, Greeley, has stated that prior to implementation it will, through signing of the Project Partnership Agreement, agree to perform the required items of cooperation including provision of all needed real estate interests, provision of cash as needed beyond real estate values to constitute its share of total costs, and post-construction operation and maintenance of the project.
I recommend that the plan proposed herein for flood risk management be approved and transitioned to the Section 205 Program for design and implementation as a Federal project.
I further recommend that the plan proposed herein for aquatic ecosystem purposes be approved and implemented as a Federal specifically authorized project.
This recommendation reflects the information available at this time and current departmental policies governing formulation of individual projects. They do not reflect program and budgeting priorities inherent in the formulation of a national Civil Works construction program nor the perspective of higher review levels within the Executive Branch.
Joel R. Cross Colonel, Corps of Engineers District Engineer
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16. BIBLIOGRAPHY
Center for Invasive Plant Management. (2009). Invasive plant information: Worst weeds in the west. Accessed from: http://www.weedcenter.org/inv_plant_info/worst.html#cheatgrass
Colorado Department of Public Health and Environment. (2008). State of Colorado implementation plan to meet the requirements of Clean Air Act Section 110 (a)(2)(D)(i)(I) interstate transport regarding the 1997 8-hour ozone standard. Accessed from: http://www.colorado.gov/airquality/documents/deno308/Interstate%20Transport%20SIP %20-%20Final.pdf
Colorado Department of Transportation. (2008). Federally-listed species in Colorado. Accessed from: http://www.dot.state.co.us/environmental/Wildlife/THREATENED&ENDANGEREDLS T.pdf
Davies, K. Re: Fish species in the CLP near Greeley. Message to Laura Steger. 2008 Dec 4, 2:35pm [cited Threatened and Endangered List [Internet). Denver, CO: Colorado Division of Wildlife; 2007 October 15.
Hutchison, M. (1990). Vegetation management guideline: Reed canary grass (Phalaris arundinacea). Accessed from: http://www.inhs.uiuc.edu/chf/outreach/VMG/rcanarygr.html
Lyons, K. E. (1998). Element stewardship abstract for Cardaria draba (L.) Desv. Heart-podded hoary cress, Cardaria chalepensis (L.) Hand-Maz. Lens-podded hoary cress, and Cardaria pubescens (C.A. Meyer) Jarmolenko Globe-podded hoary cress. Accessed from: http://www.invasive.org/gist/esadocs/documnts/card_sp.pdf
Pierson, K. (2007). Sawtooth National Forest invasive species: Kochia. Accessed from: http://www.fs.fed.us/r4/sawtooth/botany/weeds/kochia.htm
Plant Conservation Alliance. (2009). Plant Conservation Alliance’s Alien Plant Working Group least wanted: Siberian elm. Accessed from: http://www.nps.gov/plants/ALIEN/fact/ulpu1.htm
U.S. Army Corps of Engineers, Omaha District. (2004). Section 905(b) reconnaissance study preliminary analysis Cache la Poudre River – Greeley, CO flood damage reduction and environmental restoration study.
U.S. Army Corps of Engineers, Omaha District. (April 2008). Northern Integrated Supply Project, applicant Northern Colorado Water Conservancy District, draft environmental impact statement.
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U.S. Army Corps of Engineers, Omaha District. (March 19, 2013). Cache la Poudre at Greeley, CO – Feasibility study, preliminary interior drainage analysis.
U.S. Army Corps of Engineers. (2000). Planning guidance notebook (ER-1105-2-100). Accessed from: http://planning.usace.army.mil/toolbox/library/ERs/entire.pdf
U.S. Census Bureau. (2011). Profile of general population and housing characteristics: 2010. Accessed July 20, 2011, from: http://factfinder2.census.gov/
U.S. Environmental Protection Agency. (2013). Currently designated nonattainment areas for all criteria pollutants. Accessed April 2, 2014 from: http://www.epa.gov/oar/oaqps/greenbk/ancl.html
Wikipedia. (n.d.). 2013 Colorado floods. Accessed March 24, 2014 from: http://en.wikipedia.org/wiki/2013_Colorado_floods
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