Final Design Report - East Shade Shelters.pdf

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CHERRY CREEK RESERVOIR SHORELINE

STABILIZATION – EAST SHADE

SHELTERS SITE

FINAL DESIGN REPORT

PREPARED BY

Alan Leak

Jessie Nolle

Jericho Rapp

RESPEC

720 South Colorado Boulevard

Suite 410 S

Denver, Colorado 80246

PREPARED FOR

Cherry Creek Basin Water Quality Authority

8390 East Crescent Parkway

Suite 300

Greenwood Village, CO 80111

JULY 2024

Project Number W0173.21001

FINAL Design Report i

TABLE OF CONTENTS

1.0 DESIGN TEAM

2.0 PROJECT DESCRIPTION

2.1 PROJECT OVERVIEW

2.2 PROJECT LOCATION & DESCRIPTION

2.3 PROJECT OBJECTIVES

3.0 KEY EROSION & WATER QUALITY ISSUES

3.1 SHORELINE EROSION & INSTABILITY

3.2 PEDESTRIAN SITE USE EROSION

3.3 RUNOFF EROSION & CONCENTRATED FLOWS

4.0 DESIGN RESEARCH & PROCESS

4.1 MATERIAL HEIRARCHY MATRIX

4.2 PROJECT COORDINATION

4.2.1 DESIGN SPRINT & OTHER MEETINGS

4.2.2 SITE CONSTRAINTS

5.0 RECOMMENDED DESIGN

5.1 SHORELINE EROSION & INSTABILITY SOLUTIONS

5.2 PEDESTRIAN SITE USE EROSION SOLUTIONS

5.3 RUNOFF EROSION & CONCENTRATED FLOW SOLUTIONS

6.0 CONCLUSION

6.1 SUMMARY OF PROJECT OBJECTIVES

6.2 OPINION OF PROBABLE COSTS

6.3 RECOMMENDED DESIGN IMPLEMENTATION

7.0 REFERENCES

APPENDIX A USGS WEB SOIL SURVEY ................................................................................................................................... I

APPENDIX B CHERRY CREEK RESERVOIR WATER SURFACE ELEVATIONS ......................................................................... II

APPENDIX C MATERIAL HEIRARCHY MATRIX WITH DETAIL PAGES .................................................................................... III

APPENDIX D PRELIMINARY COST ESTIMATES ...................................................................................................................... IV

APPENDIX E CONSTRUCTION DRAWING SET ........................................................................................................................ V

FINAL Design Report ii

TABLE OF FIGURES

Figure 1 – Shoreline Erosion Around Existing Concrete Staircase

Figure 2 – Bank Cut

Figure 3 – Habit Path to Shoreline from Shade Shelter

Figure 4 – Curb Cut at Edge of Roadway

1.0 DESIGN TEAM

Lead Consultant

Alan Leak – Principal

Jessie Nolle – Project Manager

Jericho Rapp – Project Engineer

Subconsultant – Environmental Permitting

Tim DeMasters – Principal / Senior Ecologist

Korby Mintken – Lead Biologist / Project Manager

Subconsultant – Landscape Architecture

Tina Bishop – Principal

Mengying Li – Landscape Designer

Subconsultant – Surveying

Aaron Murphy – Land Survey Task Manager

Shawn Clarke – Survey Project Manager

2.0 PROJECT DESCRIPTION

2.1 PROJECT OVERVIEW

The goal of the East Shade Shelters Shoreline Stabilization Project (Project) is to reduce the discharge of phosphorus and other contaminants into the Chery Creek Reservoir, located in Arapahoe County, through the means and methods of shoreline stabilization. The Cherry Creek Basin Water Quality Authority (CCBWQA) is the management, funding, and lead agency for the project. Colorado Parks & Wildlife (CPW) is a key stakeholder on the project and will also provide funding. CPW attends progress meetings, provides design input, and will own the Project, while both CPW and CCBWQA will maintain the site. Staff at the Cherry Creek State Park & Reservoir

(CCSP) represent CPW. United States Army Corps of Engineers (USACE) owns the property and will review and authorize the improvements as part of their 408 permit review of the project. The following report will cover the improvements being proposed at the ESS site.

2.2 PROJECT LOCATION & DESCRIPTION

The ESS site is located along Boat Ramp Access Road, approximately 1 mile from the East Park entrance (Parker

Road). This site is approximately 0.3 acres, located between the Swim Beach to the north, the end of the concrete access trail to the south, the edge of the roadway to the east, and the water’s edge to the west. The

ESS site includes about 400 feet of shoreline. The site experiences significant pedestrian travel, in the form of fishing access, swimming access, and other miscellaneous recreational use with parking and official recreational facilities nearby. The site features steep banks due to high erosion, ranging from completely vertical to 2H:1V, with flatter top of banks and a moderate amount of existing vegetation in the form of native grasses, shrubs, and trees. See Appendix A for soils information for the project.

2.3 PROJECT OBJECTIVES

Objective 1. Improve the water quality at the project site by stabilizing the existing shorelines and banks through restorative measures and improved vegetation cover.

Objective 2. Minimize impacts of future erosion from waves, ice, surface runoff, and pedestrian site use at the project site while protecting existing infrastructure.

Objective 3. Maintain current pedestrian access while preventing additional habit paths from forming; no enhancements to recreational facilities or uses are planned.

Objective 4. Minimize maintenance requirements of improvements while preserving long-term performance.

3.0 KEY EROSION & WATER QUALITY ISSUES

Three interactive elements drive the existing and future erodibility and water quality issues at the project site.

Those three are shoreline erosion and instability, pedestrian site use, and concentrated flow from runoff. They all influence each other and must all be addressed collectively to meet the project objectives. Erosion at the site is primarily driven wave and ice action that undercuts existing vegetation which is then further destabilized and eroded by heavy pedestrian traffic.

3.1 SHORELINE EROSION & INSTABILITY

Wave and ice action have eroded the bank at the shoreline over time and resulted in a vertical bank cut that ranges from 6 inches to 6 feet. These bank cuts occur where there is no bank armoring or vegetation with hardy roots. The erodible soil in the area means that bank cuts can lead to further instability and a high risk of future erosion. Runoff from upstream areas that passes over a bank cut can cause further toe erosion and slippage of the bank. High pedestrian use in the area has led to the establishment of unstable habit paths that are at risk for additional erosion. Every eroded location that is not stabilized risks being an opportunity for high concentrations of pollutants to be carried into the reservoir. Figure 1 shows what wave and ice action have done to the embankment around an existing concrete staircase. If left unchecked, the soils beneath the staircase will continue to be undercut and may lead to instability of the structure.

There are multiple areas of severe bank cut at the site. Figure 2 below is an example. These cuts exist west of both shade shelters and beneath a portion of the concrete access path within the project limits. There are non-cohesive exposed soils and a lack of vegetation at each of these cuts, and they are extremely susceptible to further erosion.

Figure 1 – Shoreline Erosion Around Existing Concrete Staircase

Figure 2 – Bank Cut

3.2 PEDESTRIAN SITE USE EROSION

Pedestrians at CCSP want to utilize the entirety of the park’s facilities, not just the official ones. This is especially true of the shoreline. Habit paths have been formed when pedestrians have perceived an easier or faster way to reach a park amenity than provided by official trails. High use over time results in these habit paths becoming barren of vegetation. They may become more compacted than the surrounding areas, reducing their ability to infiltrate runoff and becoming concentrated flow paths that may result in even more erosion. Alternately, the surfaces of these paths may be churned up by high foot traffic or by users dragging items such as coolers along them, leaving a high potential for erosion. If left unchecked, unstable habit paths may widen over time and grow in their susceptibility to erosion.

Figure 3 shows a habit path from a shade shelter through a bank cut down to the shoreline. This habit path and the associated erosion are circular processes. A bank cut caused by waves and wind combines with a pedestrian route to the shoreline to increase the rate of erosion through the use of the habit path loosening soils and facilitating bank degradation from wave and ice action. Note that a concrete staircase from the shelter to the shore exists not far from this habit path.

Numerous habit paths have been formed at the site to bypass the concrete staircase accesses. It is important to ensure that new bank stabilization will not be undone by unencumbered or unmitigated pedestrian access.

Stabilized access to the lower habit path along the shoreline must be provided from the shade shelters to prevent the formation of habit paths at locations determined by the whims of park users.

Figure 3 - Habit Path to Shoreline from Shade Shelter

3.3 RUNOFF EROSION & CONCENTRATED FLOWS

The site is downgradient of a large tributary area; thus it receives a relatively significant amount of runoff during storm events. Runoff from smaller events is likely infiltrated, especially where vegetative cover increases the soil’s potential for infiltration. But runoff beyond what can be infiltrated will collect and transport sediment carrying phosphorus and other pollutants into the reservoir. Healthy vegetation and intentional site grading can mitigate sediment transport, while unchecked bank erosion and habit path development can increase it, causing more pollutants to reach the water. Concentrated flow paths that form along habit paths reduce the amount of time available for infiltration and sediment settling upstream of the reservoir. The stabilization of the shoreline and protection from pedestrian overuse will minimize water quality impacts.

Figure 4 shows parking along the roadway at the ESS site and one of two curb cuts directing runoff to the flat top of bank. The top of bank features large, mature trees and slight dips in grading that act as great infiltration basins already. However, the proximity of roadway pavement to the project site means significant runoff in a major storm event will easily bypass the natural sedimentation basins and will carry sediment, phosphorus contained in already eroded soils, and other roadway pollutants to the reservoir.

The severe bank cuts at this site are unstable and may be inordinately affected by sheet flow runoff. There is also a severe bank cut beneath the concrete access path at the southern end of the ESS site. Runoff infiltrating prior to this path is likely transported under the path and could expand the cut farther under the path in the future. If this were to occur, the path may become structurally unstable.

Figure 4 - Curb Cut at Edge of Roadway

4.0 DESIGN RESEARCH & PROCESS

The first step in the design process involved compiling research into the causes of shoreline erosion. Current methods of shoreline stabilization and erosion prevention were analyzed to create a material hierarchy matrix

(MHM). The MHM guided development of conceptual alternatives that were presented and discussed at the design sprint meeting. Following that meeting, the preliminary design was focused and submitted. Steps were then taken to lower project costs while still meeting overall goals through value engineering that led to a final design submittal and report.

4.1 MATERIAL HEIRARCHY MATRIX

The MHM summarized the analysis of numerous methods of shoreline stabilization, water quality improvement, and erosion prevention. The methods consisted of both hardscape engineered methods and natural “living shoreline” methods. Each method was associated with multiple use variables or shoreline characteristics that applied to that method. Each method then received a grade or designation as to how applicable it was to certain forces of erosion, how it fit with certain site characteristics, and how it improved site conditions. When paired with the site survey received from Harris Kocher Smith (HKS) and site visits conducted by the project team, the

MHM guided the development of two alternative concept plans. See Appendix C for the MHM with detail pages explaining the methods included.

4.2 PROJECT COORDINATION

To provide the project sponsors with a range of possible options, RESPEC prepared one alternative the sought to improve all aspects of the project site with an emphasis on hardscaped methods and a second alternative that proposed solutions only at the most critical areas and featured an emphasis on natural methods. The goal of this process was to meet in the middle on a design that satisfied project goals and stakeholder input.

4.2.1 DESIGN SPRINT & OTHER MEETINGS

To focus the design and move towards preliminary construction plans, the project team met for a design sprint at the CCSP with representatives from the CCBWQA, CPW, RESPEC, Mundus Bishop, and Corvus in attendance.

The concepts and proposed methods were discussed for feasibility, maintenance, constructability, and cost. A site visit was conducted after the office meeting.

A second meeting was held after the design sprint to review the conceptual design plan for each site that had been developed after the design sprint. This design was created from feedback received during the design sprint and site visit, and considered the constraints discussed in the next section.

Another all hands meeting was held virtually after the preliminary report and construction drawing submittal. The goal was to discuss comments received on the submittal and find a path forward. This involved value engineering the design in order to make the costs more feasible for both CPW and CCBWQA. This discussion ultimately led to the hiring of an independent cost estimator, and the removal of certain design items that were included in the preliminary submittal.

4.2.2 DESIGN DECISIONS & SITE CONSTRAINTS

This section contains some of the feedback and site constraints included in the design.

Due to the heavy pedestrian traffic found at the site, both CPW and CCBWQA preferred the use of riprap protection at the toe of the bank, citing that the chaotic and unpredictable nature of the pedestrians could negatively impact the establishment of vegetation in the most critical locations. This did not rule out vegetation establishment for the entirety of the project. Instead, in areas still needing re-vegetation, temporary and permanent fencing shall be used to attempt to keep the areas free of foot traffic.

To deal with large bank cuts, CCBWQA suggested using boulder bulkhead walls as had been done previously at the reservoir. Historic water surface elevation charts guided the implementation of these at the site, as well as the joint planting proposed below the walls.

A few stabilization methods involve using live plant cuttings to establish vegetation quickly. These live cuttings require their roots to reach the reservoir mean high water mark (MHWM) to establish. Corvus suggested that live cuttings of drought-tolerant plants may be used at higher elevations to allow the proposed methods to work as intended.

CCBWQA had indicated that usually a level of water quality treatment is provided by projects like this one. It was determined that this project would not feature treatment due to the amount of maintenance required by these features and the site naturally providing some amount of infiltration at the top of bank already.

5.0 RECOMMENDED DESIGN

Design plans are in Appendix E. Discussion of the site below features a summary of the design elements used and their overall purpose. The exact benefits of the methods are detailed in subsections below.

One of the primary drivers of erosion is the heavy pedestrian site use and their propensity to form their own habit paths as opposed to using formalized or official paths that run through the site. To deal with this, a thoughtful pedestrian control plan was developed that will see the closure of certain problematic habit paths where concentrated flow paths have formed, the addition of a boulder staircase from the far north shade shelter leading to the shoreline, and a permanent fence at the stable top of bank that will path pedestrians to the staircases or more stable habit paths. To assist the fence, wayfaring signage will be installed indicating where pedestrians should be accessing the shoreline.

Where banks are severely damaged between the staircases (existing and proposed), they will be stabilized by grading back to a stable slope of 3H:1V. From the back of the main shoreline habit path, 36 inches of Type H soil riprap will be installed up to an elevation of 5555.00 feet. This elevation was chosen to ensure a severe flooding event would be contained based on the historic data mentioned above. The site will be revegetated above this elevation up to the massive rail fence; a planting fence will surround these areas until vegetation establishes. In locations that a 3H:1V slope is not feasible, a boulder wall will be installed above the riprap. To stabilize the sides of the staircases, 24 inches of Type M riprap in a 12 inch swath will be used to armor the grading and protect from pedestrians walking along the staircases. Habit paths in this area will be removed as a result of this work.

The main habit path runs along the shoreline and intersect with the landings of the two existing concrete staircases. The proposed boulder staircase shall connect to the main habit path. Where this habit path connects to the staircase landings, it will be stabilized using crusher fines to prevent further degradation around the staircase bases. An existing habit path at the north end of the site that connects between the proposed staircase and the main habit path will be regraded to feature a local slope of 10H:1V with intermittent boulder steps. This path has been identified as a popular access to swim beach, and thus it will be stabilized using crusher fines and feature similar armoring on the downslope as the staircases to prevent erosion from pedestrians dragging coolers and other containers to the beach.

On the south end of the project, south of the concrete staircase and west of the concrete access ramp, there is heavy bank cut that will be graded at 3H:1V from the curb of the access ramp to the shoreline. All existing vegetation, trees, and shrubs will remain if viable. This regraded area will feature 36 inches of Type H soil riprap, effectively cutting off the main habit path south of the furthest south concrete staircase and preventing pedestrians from continuing south along the shoreline. The official path to reach the shoreline south of the project site is the concrete access ramp.

All areas of Type H soil riprap shall feature joint planting that increases the underlying soil’s stability and aids in the aesthetic look of the project site. Once these live stakes grow, they will mask the hardscape nature of this engineering solution.

At the bottom of the middle staircase, a small boulder wall will be constructed where there is severe bank cut.

This will allow pedestrians to access the shoreline without damaging the bank and guide them along the preferred path. Fieldstone is required at the reservoir MHWM at the base of the large boulders to protect them from ice action and undercutting. In addition to that location, fieldstone will be installed anywhere along the reservoir MHWM that does not already feature riprap revetment. Fieldstone is made up of 12 inches of Type L riprap. An analysis of most probable reservoir water surface elevations guided the extent of the fieldstone installation. It was determined that fieldstone should be installed 1.5 feet above and below the reservoir MHWM of 5550.00 feet. See Appendix B for reservoir water surface variances and analysis.

5.1 SHORELINE EROSION & INSTABILITY SOLUTIONS

Repairing the severe bank cuts with large amounts of riprap and vegetation will protect against future wave and ice action. Vegetation both on the upper bank and within the riprap will have dense root systems to harden the soil and prevent undercutting of the bank.

5.2 PEDESTRIAN SITE USE EROSION SOLUTIONS

Removing the habit paths and corralling pedestrians to use the staircases with a larger access path will limit future human-caused erosion at this site. Fencing with directional signs will facilitate finding the closest shore access path. Pedestrians walking along the shore from the north will be guided along the main habit path and forced to use designated shoreline paths once reaching the southernmost staircase.

5.3 RUNOFF EROSION & CONCENTRATED FLOW SOLUTIONS

All the measures described above shall aid in runoff infiltration and reduce sediment transport. To ensure the runoff from the roadway is treated, the bioretention basins will capture and treat it before it reaches the reservoir.

6.0 CONCLUSION

6.1 SUMMARY OF PROJECT OBJECTIVES

If properly implemented, the design will meet the project objectives and have no adverse effect on adjacent shorelines or the reservoir.

Objective 1. Improve the water quality at the project site by stabilizing the existing shorelines and banks through restorative measures and improved vegetation cover.

• Establishment of vegetation in areas of previously concentrated flow and steep banks will armor the soil and lead to increased infiltration and settling of sediment. Bioretention and trench packs will act as an extra layer of water quality control while also increasing vegetation cover.

Objective 2. Minimize impacts of waves, ice, surface runoff, and pedestrian use at the project site while protecting existing infrastructure.

• Fieldstone and boulder walls installed along the shoreline will prevent wave and ice action from eroding the bank in the future. Installation of riprap will help prevent erosion caused by park users and will armor the banks against severe flooding events. Repair of erosion around existing infrastructure will protect existing structures. Rocks and riprap will armor banks from sheet runoff erosion.

Objective 3. Maintain current pedestrian site access while preventing additional habit paths from forming and without enhancing recreational facilities and uses at project site.

• Stabilization or removal of selected habit paths will maintain site access while removing potential for further erosion. Fencing and signage will help vegetation establish and further create a barrier to control pedestrians. Crusher fines will stabilize paths while remaining natural looking. A proposed trail at the site will discourage park users damaging other parts of the site.

Objective 4. Minimize maintenance requirements of proposed solutions while preserving long-term performance.

• Improvements are proposed only in critical locations. Natural materials allow for lower cost acquisition. Extensive use of rock will benefit long-term performance. Temporary irrigation will be required to establish vegetation, but less maintenance will be required to upkeep site after it is established.

6.2 OPINION OF PROBABLE COSTS

The preliminary opinion of site costs are included as an appendix to this report. Costs were computed by an independent cost estimator using current construction costs and trends in inflation.

6.3 RECOMMENDED DESIGN IMPLEMENTATION

Due to the nature of the project, a lower level of plan detail should be expected when compared to a traditional plan set. Additional data collection and site visits will be required to ensure an accurate and effective design.

Additional drawings will include a cut/fill analysis, a more detailed planting plan, and full grading, erosion, and sediment control (GESC) plans. Daily monitoring of construction will be required.

7.0 REFERENCES

United States Department of Agriculture, Natural Resources Conservation Service, August 22, 2022. “Custom

Soil Resource Report for Arapahoe County, Colorado”.

i

APPENDIX A

USGS WEB SOIL SURVEY

United States Department of Agriculture

A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants

Custom Soil Resource Report for

Arapahoe County, Colorado

Natural Resources Conservation Service

August 22, 2022

Custom Soil Resource Report Soil Map

512200 512400 512600 512800 513000 513200 513400 513600

512200 512400 512600 512800 513000 513200 513400 513600

39° 39' 19'' N

4°

1'

0' ' W

39° 39' 19'' N

4°

0'

7' ' W

39° 38' 15'' N

4°

1'

0' ' W

39° 38' 15'' N

4°

0'

7' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 450 900 1800 2700

Feet 0 100 200 400 600

Meters Map Scale: 1:9,690 if printed on A portrait (8.5" x 11") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Map Unit Polygons

Soil Map Unit Lines

Soil Map Unit Points

Special Point Features Blowout

Borrow Pit

Clay Spot

Closed Depression

Gravel Pit

Gravelly Spot

Landfill

Lava Flow

Marsh or swamp

Mine or Quarry

Miscellaneous Water

Perennial Water

Rock Outcrop

Saline Spot

Sandy Spot

Severely Eroded Spot

Sinkhole

Slide or Slip

Sodic Spot

Spoil Area

Stony Spot

Very Stony Spot

Wet Spot

Other

Special Line Features

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:20,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Arapahoe County, Colorado Survey Area Data: Version 17, Aug 31, 2021

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Jun 9, 2021—Jun 12, The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Map Unit Legend

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

AED Arents, Earthen Dam 19.9 4.7%

BvC Bresser-Truckton sandy loams, 3 to 5 percent slopes

24.2 5.7%

BvE Bresser-Truckton sandy loams, 5 to 20 percent slopes

3.1 0.7%

NlB Nunn loam, 1 to 3 percent slopes

1.6 0.4%

St Sand pits 131.9 31.2%

TrC Truckton loamy sand, 0 to 3 percent slopes

5.4 1.3%

TrE Truckton loamy sand, 5 to 20 percent slopes

0.9 0.2%

W Water 235.7 55.7%

Totals for Area of Interest 422.8 100.0%

Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit.

A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class.

Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions.

Each description includes general facts about the unit and gives important soil properties and qualities.

Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.

Some map units are made up of two or more major soils or miscellaneous areas.

These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps.

The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.

An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.

Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example.

Arapahoe County, Colorado

AED—Arents, Earthen Dam

Map Unit Setting National map unit symbol: 12f73 Elevation: 600 to 1,300 feet Mean annual precipitation: 24 to 31 inches Mean annual air temperature: 50 to 57 degrees F Frost-free period: 190 to 210 days Farmland classification: Farmland of statewide importance

Map Unit Composition Arents, earthen dam: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Arents, Earthen Dam

Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8 Hydric soil rating: Unranked

BvC—Bresser-Truckton sandy loams, 3 to 5 percent slopes

Map Unit Setting National map unit symbol: 34y5 Elevation: 4,500 to 6,800 feet Mean annual precipitation: 12 to 18 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 125 to 180 days Farmland classification: Prime farmland if irrigated and the product of I (soil erodibility) x C (climate factor) does not exceed 60

Map Unit Composition Bresser and similar soils: 55 percent Truckton and similar soils: 30 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Bresser

Setting Landform: Playas, drainageways, stream terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Noncalcareous sandy alluvium and/or noncalcareous sandy eolian deposits

Typical profile H1 - 0 to 6 inches: sandy loam H2 - 6 to 26 inches: sandy clay loam H3 - 26 to 32 inches: gravelly sandy loam H4 - 32 to 60 inches: gravelly loamy coarse sand

Properties and qualities Slope: 3 to 5 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high

(0.57 to 2.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 10 percent Available water supply, 0 to 60 inches: Moderate (about 6.7 inches)

Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Ecological site: R049XB210CO - Sandy Foothill Hydric soil rating: No

Description of Truckton

Setting Landform: Ridges Down-slope shape: Linear Across-slope shape: Linear Parent material: Eolian deposits

Typical profile H1 - 0 to 5 inches: sandy loam H2 - 5 to 20 inches: sandy loam H3 - 20 to 60 inches: sandy loam

Properties and qualities Slope: 3 to 5 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Low (about 6.0 inches)

Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: A Ecological site: R049XB210CO - Sandy Foothill Hydric soil rating: No

Minor Components

Nunn Percent of map unit: 8 percent Hydric soil rating: No

Ascalon Percent of map unit: 7 percent Hydric soil rating: No

BvE—Bresser-Truckton sandy loams, 5 to 20 percent slopes

Map Unit Setting National map unit symbol: 34y6 Elevation: 4,500 to 6,800 feet Mean annual precipitation: 12 to 18 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 125 to 180 days Farmland classification: Not prime farmland

Map Unit Composition Bresser and similar soils: 50 percent Truckton and similar soils: 35 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Bresser

Setting Landform: Drainageways, stream terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Noncalcareous sandy alluvium and/or noncalcareous sandy eolian deposits

Typical profile H1 - 0 to 5 inches: sandy loam H2 - 5 to 16 inches: sandy clay loam H3 - 16 to 28 inches: gravelly sandy loam H4 - 28 to 60 inches: gravelly loamy coarse sand

Properties and qualities Slope: 5 to 20 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high

(0.57 to 2.00 in/hr)

Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 10 percent Available water supply, 0 to 60 inches: Moderate (about 6.1 inches)

Interpretive groups Land capability classification (irrigated): 6e Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Ecological site: R049XB210CO - Sandy Foothill Hydric soil rating: No

Description of Truckton

Setting Down-slope shape: Linear Across-slope shape: Linear Parent material: Eolian deposits

Typical profile H1 - 0 to 5 inches: sandy loam H2 - 5 to 17 inches: sandy loam H3 - 17 to 60 inches: sandy loam

Properties and qualities Slope: 5 to 20 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Low (about 5.9 inches)

Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: A Ecological site: R049XB210CO - Sandy Foothill Hydric soil rating: No

Minor Components

Ascalon Percent of map unit: 10 percent Hydric soil rating: No

Nunn Percent of map unit: 5 percent Hydric soil rating: No

NlB—Nunn loam, 1 to 3 percent slopes

Map Unit Setting National map unit symbol: 2tln2 Elevation: 3,900 to 6,250 feet Mean annual precipitation: 13 to 16 inches Mean annual air temperature: 46 to 54 degrees F Frost-free period: 135 to 160 days Farmland classification: Prime farmland if irrigated

Map Unit Composition Nunn and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Nunn

Setting Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Pleistocene aged alluvium and/or eolian deposits

Typical profile Ap - 0 to 6 inches: loam Bt1 - 6 to 10 inches: clay loam Bt2 - 10 to 26 inches: clay loam Btk - 26 to 31 inches: clay loam Bk1 - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam

Properties and qualities Slope: 1 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 7 percent Maximum salinity: Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum: 0.5 Available water supply, 0 to 60 inches: High (about 9.2 inches)

Interpretive groups Land capability classification (irrigated): 3e

Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No

Minor Components

Wages Percent of map unit: 8 percent Landform: Alluvial fans, terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No

Fort collins Percent of map unit: 5 percent Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No

Haverson, very rarely flooded Percent of map unit: 2 percent Landform: Alluvial fans, drainageways, terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear, concave Ecological site: R067BY036CO - Overflow Hydric soil rating: No

St—Sand pits

Map Unit Composition Sand pits: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Sand Pits

Setting Microfeatures of landform position: Sand boils Down-slope shape: Linear Across-slope shape: Linear Parent material: Sand pits sandy

Typical profile H1 - 0 to 10 inches: sand

H2 - 10 to 60 inches: sand

Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 8s Hydrologic Soil Group: A Hydric soil rating: No

Minor Components

Water Percent of map unit: 15 percent Hydric soil rating: No

Aquolls Percent of map unit: 5 percent Landform: Marshes Hydric soil rating: Yes

TrC—Truckton loamy sand, 0 to 3 percent slopes

Map Unit Setting National map unit symbol: 2yvrl Elevation: 4,200 to 5,600 feet Mean annual precipitation: 12 to 17 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 125 to 155 days Farmland classification: Farmland of statewide importance

Map Unit Composition Truckton and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Truckton

Setting Landform: Terraces, interfluves Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Wind re-worked alluvium derived from arkose

Typical profile A - 0 to 6 inches: loamy sand Bt1 - 6 to 10 inches: sandy loam Bt2 - 10 to 16 inches: sandy loam C - 16 to 80 inches: loamy coarse sand

Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained

Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): High (2.00 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 1 percent Maximum salinity: Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: Low (about 4.4 inches)

Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 6e Hydrologic Soil Group: A Ecological site: R067BY024CO - Sandy Plains Hydric soil rating: No

Minor Components

Blakeland Percent of map unit: 8 percent Landform: Interfluves, hills Landform position (two-dimensional): Summit, shoulder, backslope Landform position (three-dimensional): Side slope, crest Down-slope shape: Convex, linear Across-slope shape: Convex, linear Ecological site: R067BY015CO - Deep Sand Hydric soil rating: No

Bresser Percent of map unit: 5 percent Landform: Terraces, interfluves Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: R067BY024CO - Sandy Plains Hydric soil rating: No

Vona Percent of map unit: 5 percent Landform: Dunes, hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down-slope shape: Convex, linear Across-slope shape: Convex, linear Ecological site: R067BY024CO - Sandy Plains Hydric soil rating: No

Urban land Percent of map unit: 2 percent Hydric soil rating: No

TrE—Truckton loamy sand, 5 to 20 percent slopes

Map Unit Setting National map unit symbol: 34zp Elevation: 4,500 to 6,500 feet Mean annual precipitation: 12 to 18 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 125 to 180 days Farmland classification: Not prime farmland

Map Unit Composition Truckton and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Truckton

Setting Landform: Gullies, drainageways Down-slope shape: Linear Across-slope shape: Linear Parent material: Sand loamy eolian sands and/or loam sandy eolian sands

Typical profile H1 - 0 to 5 inches: loamy sand H2 - 5 to 27 inches: sandy loam H3 - 27 to 60 inches: sandy loam

Properties and qualities Slope: 5 to 20 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Low (about 6.0 inches)

Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: A Ecological site: R049XB210CO - Sandy Foothill Hydric soil rating: No

Minor Components

Blakeland Percent of map unit: 13 percent Hydric soil rating: No

Bresser Percent of map unit: 5 percent Hydric soil rating: No

Samsil Percent of map unit: 2 percent Hydric soil rating: No

W—Water

Map Unit Composition Water: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit.

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Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31.

Federal Register. July 13, 1994. Changes in hydric soils of the United States.

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Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States.

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Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.

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Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580

Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section.

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United States Department of Agriculture, Natural Resources Conservation Service.

National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

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296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?

cid=nrcs142p2_053624

United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

Custom Soil Resource Report http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624 http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf ii

APPENDIX B

CHERRY CREEK RESERVOIR WATER SURFACE ELEVATIONS

0.33% 1.76% 3.65%…