coal creek and rock creek major drainageway plan

COAL CREEK AND ROCK CREEK MAJOR DRAINAGEWAY PLAN Project Sponsors:

Prepared by:

October 2014

720 South Colorado Boulevard Suite 410 S Denver, Colorado 80246 phone (303) 757-3655 fax (303) 300-1635

BOULDER COUNTY

CITY AND COUNTY OF BROOMFIELD

TOWN OF ERIE

URBAN DRAINAGE AND FLOOD CONTROL DISTRICT

CITY OF LAFAYETTE

CITY OF LOUISVILLE

TOWN OF SUPERIOR

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RESPEC Consulting & Services 720 South Colorado Boulevard, Suite 410 S

Denver, CO 80246

COAL CREEK AND ROCK CREEK MAJOR DRAINAGEWAY PLAN

October 2014 Ms. Shea Thomas Manager of Master Planning Urban Drainage and Flood Control District 2480 West 26th Avenue, Suite 156-B Denver, CO 80211 Subject: Coal Creek and Rock Creek Major Drainageway Plan UDFCD Agreement No. 12-01.17 Dear Ms. Thomas: RESPEC Consulting & Services is pleased to submit this report, titled Coal Creek and Rock Creek Major Drainageway Plan, dated October 14, 2014. We would like to acknowledge the help and support in the preparation of this report that was furnished by Boulder County, the City and County of Broomfield, the Town of Erie, the City of Lafayette, the City of Louisville, and the Town of Superior. In order to minimize the impacts of flooding, this conceptual design lays out strategies for drainage and conveyance within the study area. The recommendations improve the conveyance efficiency and water quality as well as reduce the flood hazards and erosion along Coal Creek and Rock Creek. The enclosed text and drawings present the improvements in our conceptual design for the Coal Creek and Rock Creek drainageways. These improvements consist of open channels, bank stabilization, culverts, and bridges.

Thank you for the opportunity to complete this project. Best regards, RESPEC Consulting & Services _____________________________________________________________ Rick R. Moser, P.E. Principal _____________________________________________________________ David P. Delagarza, P.E. Project Manager _____________________________________________________________ Tony H. Tran, E.I. Project Engineer _____________________________________________________________ Michael J. Bannister Project Engineer

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Executive Summary .................................................................................................... ES-1

ES.1 Purpose and Objectives ..................................................................................................................... ES-1 ES.2 Planning Process ................................................................................................................................ ES-1 ES.3 Project Area ....................................................................................................................................... ES-3 ES.4 Hydrologic Analysis ............................................................................................................................ ES-3 ES.5 Hydraulic Analysis .............................................................................................................................. ES-4 ES.6 Alternatives Evaluation ...................................................................................................................... ES-4 ES.7 Recommended Plan ........................................................................................................................... ES-5 ES.8 Selected Plan and Conceptual Design ................................................................................................ ES-5

Section 1 Introduction .......................................................................................... 1-1

1.1 Authorization ...................................................................................................................................... 1-1 1.2 Purpose and Scope ............................................................................................................................. 1-1 1.3 Planning Process ................................................................................................................................. 1-1 1.4 Mapping and Surveys .......................................................................................................................... 1-1 1.5 Data Collection .................................................................................................................................... 1-2 1.6 Acknowledgements ............................................................................................................................ 1-2

Section 2 Study Area ............................................................................................ 2-1

2.1 Project Area ........................................................................................................................................ 2-1 2.2 Land Use .............................................................................................................................................. 2-2 2.3 Reach Description ............................................................................................................................... 2-2 2.4 Flood History ...................................................................................................................................... 2-3 2.5 Environmental Assessment ................................................................................................................. 2-4

Section 3 Hydrologic Analysis .............................................................................. 3-1

3.1 Overview ............................................................................................................................................. 3-1 3.2 Design Rainfall..................................................................................................................................... 3-1 3.3 Subwatershed Characteristics ............................................................................................................ 3-1

3.3.1 Subwatershed Delineation .................................................................................................... 3-1 3.3.2 Watershed Imperviousness ................................................................................................... 3-2 3.3.3 Soils Information .................................................................................................................... 3-2

3.4 Hydrograph Routing ............................................................................................................................ 3-2 3.5 Previous Studies .................................................................................................................................. 3-2 3.6 Results of Analysis ............................................................................................................................... 3-3

Section 4 Hydraulic Analysis ................................................................................ 4-1

4.1 Evaluation of Existing Facilities ........................................................................................................... 4-1 4.2 Flood Hazards ..................................................................................................................................... 4-2 4.3 Previous Analyses ............................................................................................................................... 4-2

Section 5 Alternatives Analysis ............................................................................ 5-1

5.1 Alternative Development Process ...................................................................................................... 5-1 5.1.1 Criteria and Constraints ......................................................................................................... 5-1

5.2 Alternative Categories ......................................................................................................................... 5-1 5.2.1 Initial Screening of Alternative Plans ...................................................................................... 5-1

5.3 Roadway Crossing and Channel Stability Improvements .................................................................... 5-4 5.4 Alternative Hydraulics ......................................................................................................................... 5-4 5.5 Alternative Costs .................................................................................................................................. 5-4 5.6 Alternative Plans .................................................................................................................................. 5-5

5.6.1 Coal Creek Reach 1: Downstream Study Limit (Boulder Creek) to Kenosha Road ............... 5-15 5.6.2 Coal Creek Reach 2: Kenosha Road to East County Line Road ............................................. 5-15 5.6.3 Coal Creek Reach 3: East County Line Road to Old Railroad Tracks ..................................... 5-16 5.6.4 Coal Creek Reach 4: Old Railroad Tracks to Briggs Street .................................................... 5-17 5.6.5 Coal Creek Reach 5: Briggs Street to Cheesman Street ........................................................ 5-18 5.6.6 Coal Creek Reach 6: Cheesman Street to Erie Parkway ....................................................... 5-18 5.6.7 Coal Creek Reach 7: Erie Parkway to North of Irrigation Pond ............................................ 5-19 5.6.8 Coal Creek Reach 8: North of Irrigation Pond to South of Irrigation Pond .......................... 5-20 5.6.9 Coal Creek Reach 9: South of Irrigation Pond to Vista Parkway ........................................... 5-20 5.6.10 Coal Creek Reach 10: Vista Parkway to Taxiway Bridge Near Airport .................................. 5-21 5.6.11 Coal Creek Reach 11: Taxiway Bridge Near Airport to Boulder County/

Weld County Boundary ......................................................................................................... 5-22 5.6.12 Coal Creek Reach 12: Boulder County/Weld County Boundary to Baseline Road ............... 5-23 5.6.13 Coal Creek Reach 13: Baseline Road to Pedestrian Bridge Near Flagg Park Boundary ........ 5-24 5.6.14 Coal Creek Reach 14: Pedestrian Bridge Near Flagg Park Boundary to Boulder County/

Lafayette Boundary .............................................................................................................. 5-25 5.6.15 Coal Creek Reach 15: Boulder County/Lafayette Boundary to Confluence of

Coal Creek and Rock Creek ................................................................................................... 5-25 5.6.16 Coal Creek Reach 20: Confluence of Coal Creek and Rock Creek to Lafayette/

Boulder County Boundary .................................................................................................... 5-26 5.6.17 Coal Creek Reach 21: Lafayette City/Boulder County Boundary to Boulder County/

Lafayette Boundary .............................................................................................................. 5-27 5.6.18 Coal Creek Reach 22: Boulder County/Lafayette Boundary to Lafayette/

Boulder County Boundary .................................................................................................... 5-27 5.6.19 Coal Creek Reach 23: Lafayette/Boulder County Boundary to South Public Road .............. 5-28 5.6.20 Coal Creek Reach 24: South Public Road to Highway 287 .................................................... 5-29 5.6.21 Coal Creek Reach 25: Highway 287 to Lafayette/Louisville Boundary ................................. 5-30 5.6.22 Coal Creek Reach 26: Lafayette/Louisville Boundary to 96th Street .................................... 5-30 5.6.23 Coal Creek Reach 27: 96th Street to CC Golf Course Pedestrian Bridge .............................. 5-31 5.6.24 Coal Creek Reach 28: CC Golf Course Pedestrian Bridge to Highway 36.............................. 5-32 5.6.25 Coal Creek Reach 29: Highway 36 to McCaslin Boulevard ................................................... 5-33 5.6.26 Coal Creek Reach 30: McCaslin Boulevard to Superior/Boulder County Boundary ............. 5-33 5.6.27 Coal Creek Reach 31: Superior/Boulder County Boundary to 1.2 Miles Upstream ............. 5-34 5.6.28 Coal Creek Reach 32: 1.2 Miles Upstream to 3.1 Miles Upstream ....................................... 5-34 5.6.29 Coal Creek Reach 33: 3.1 Miles Upstream to Highway 128 ................................................. 5-35 5.6.30 Rock Creek Reach 40: Confluence of Coal Creek and Rock Creek to 120th Street............... 5-36 5.6.31 Rock Creek Reach 41: 120th Street to Drainageway F ......................................................... 5-36 5.6.32 Rock Creek Reach 42: Drainageway F to Lafayette/Boulder County Boundary ................... 5-37 5.6.33 Rock Creek Reach 43: Lafayette/Boulder County Boundary to Dillon Road ........................ 5-38 5.6.34 Rock Creek Reach 44: Dillon Road (EB) to Dillon Road (WB) ................................................ 5-38 5.6.35 Rock Creek Reach 45: Dillon Road (WB) to Highway 287 ..................................................... 5-39 5.6.36 Rock Creek Reach 46: Highway 287 to East of Stearns Lake ................................................ 5-40 5.6.37 Rock Creek Reach 47: East of Stearns Lake to 104th Street ................................................. 5-40 5.6.38 Rock Creek Reach 48: 104th Street to Brainard Drive .......................................................... 5-41

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5.6.39 Rock Creek Reach 49: Brainard Drive to Highway 36 .......................................................... 5-41 5.6.40 Rock Creek Reach 50: Highway 36 to Superior/Broomfield Boundary ................................ 5-42 5.6.41 Rock Creek Reach 51: Superior/Broomfield Boundary to Irrigation Structure.................... 5-43 5.6.42 Rock Creek Reach 52: Irrigation Structure to Superior/Boulder County Boundary ............ 5-43 5.6.43 Rock Creek Reach 53: Superior/Boulder County Boundary to Upstream Study Limit ........ 5-44

5.7 Qualitative Evaluation Procedure ..................................................................................................... 5-45 5.7.1 Benefit-Cost Analysis ........................................................................................................... 5-45

Section 6 Recommended Plan .............................................................................. 6-1

6.1 Plan Description .................................................................................................................................. 6-1 6.2 Water Quality Impacts ........................................................................................................................ 6-1 6.3 Operations and Maintenance ............................................................................................................. 6-2 6.4 Environmental and Safety Assessment ............................................................................................... 6-2 6.5 Cultural Assessment and Preservation ............................................................................................... 6-2

Section 7 Conceptual Design of Selected Plan .................................................... 7-1

7.1 Conceptual Design Overview .............................................................................................................. 7-1 7.2 Design Criteria ..................................................................................................................................... 7-1 7.3 Stream Stabilization ............................................................................................................................ 7-2

7.3.1 Bank Stabilization Criteria and Constraints ........................................................................... 7-3 7.3.2 Hard Bank Stabilization Measures ......................................................................................... 7-3 7.3.3 Soft Bank Stabilization Measures .......................................................................................... 7-3

7.4 Cost Estimate ...................................................................................................................................... 7-8 7.5 Conceptual Design Description ........................................................................................................... 7-8

7.5.1 Coal Creek Reach 1: Downstream Study Limit (Boulder Creek) to Kenosha Road .............. 7-13 7.5.2 Coal Creek Reach 2: Kenosha Road to East County Line Road ............................................ 7-15 7.5.3 Coal Creek Reach 3: East County Line Road to Old Railroad Tracks .................................... 7-17 7.5.4 Coal Creek Reach 4: Old Railroad Tracks to Briggs Street.................................................... 7-19 7.5.5 Coal Creek Reach 5: Briggs Street to Cheesman Street ....................................................... 7-20 7.5.6 Coal Creek Reach 6: Cheesman Street to Erie Parkway ....................................................... 7-22 7.5.7 Coal Creek Reach 7: Erie Parkway to North of Irrigation Pond ............................................ 7-23 7.5.8 Coal Creek Reach 8: North of Irrigation Pond to South of Irrigation Pond .......................... 7-25 7.5.9 Coal Creek Reach 9: South of Irrigation Pond to Vista Parkway .......................................... 7-27 7.5.10 Coal Creek Reach 10: Vista Parkway to Taxiway Bridge Near Airport ................................. 7-28 7.5.11 Coal Creek Reach 11: Taxiway Bridge Near Airport to Boulder County/

Weld County Boundary ....................................................................................................... 7-30 7.5.12 Coal Creek Reach 12: Boulder County/Weld County Boundary to Baseline Road .............. 7-32 7.5.13 Coal Creek Reach 13: Baseline Road to Pedestrian Bridge Near Flagg Park Boundary ....... 7-34 7.5.14 Coal Creek Reach 14: Pedestrian Bridge Near Flagg Park Boundary to Boulder County/

Lafayette Boundary .............................................................................................................. 7-36 7.5.15 Coal Creek Reach 15: Boulder County/Lafayette Boundary to Confluence of

Coal Creek and Rock Creek .................................................................................................. 7-37 7.5.16 Coal Creek Reach 20: Confluence of Coal Creek and Rock Creek to Lafayette/

Boulder County Boundary .................................................................................................... 7-38 7.5.17 Coal Creek Reach 21: Lafayette /Boulder County Boundary to Boulder County/

Lafayette Boundary .............................................................................................................. 7-39 7.5.18 Coal Creek Reach 22: Boulder County/Lafayette Boundary to Lafayette/

Boulder County Boundary .................................................................................................... 7-41

7.5.19 Coal Creek Reach 23: Lafayette/Boulder County Boundary to South Public Road .............. 7-43 7.5.20 Coal Creek Reach 24: South Public Road to Highway 287 .................................................... 7-45 7.5.21 Coal Creek Reach 25: Highway 287 to Lafayette/Louisville Boundary ................................. 7-46 7.5.22 Coal Creek Reach 26: Lafayette/Louisville Boundary to 96th Street .................................... 7-48 7.5.23 Coal Creek Reach 27: 96th Street to CC Golf Course Pedestrian Bridge .............................. 7-50 7.5.24 Coal Creek Reach 28: CC Golf Course Pedestrian Bridge to Highway 36.............................. 7-52 7.5.25 Coal Creek Reach 29: Highway 36 to McCaslin Boulevard ................................................... 7-54 7.5.26 Coal Creek Reach 30: McCaslin Boulevard to Superior/Boulder County Boundary ............. 7-56 7.5.27 Coal Creek Reach 31: Superior/Boulder County Boundary to 1.2 Miles Upstream ............. 7-57 7.5.28 Coal Creek Reach 32: 1.2 Miles Upstream to 3.1 Miles Upstream ....................................... 7-59 7.5.29 Coal Creek Reach 33: 3.1 Miles Upstream to Highway 128 ................................................. 7-61 7.5.30 Rock Creek Reach 40: Confluence of Coal Creek and Rock Creek to 120th Street............... 7-63 7.5.31 Rock Creek Reach 41: 120th Street to Drainageway F ......................................................... 7-65 7.5.32 Rock Creek Reach 42: Drainageway F to Lafayette/Boulder County Boundary ................... 7-66 7.5.33 Rock Creek Reach 43: Lafayette/Boulder County Boundary to Dillon Road ........................ 7-67 7.5.34 Rock Creek Reach 44: Dillon Road (EB) to Dillon Road (WB) ................................................ 7-69 7.5.35 Rock Creek Reach 45: Dillon Road (WB) to Highway 287 ..................................................... 7-70 7.5.36 Rock Creek Reach 46: Highway 287 to East of Stearns Lake ................................................ 7-72 7.5.37 Rock Creek Reach 47: East of Stearns Lake to 104th Street ................................................. 7-73 7.5.38 Rock Creek Reach 48: 104th Street to Brainard Drive .......................................................... 7-72 7.5.39 Rock Creek Reach 49: Brainard Drive to Highway 36 ........................................................... 7-75 7.5.40 Rock Creek Reach 50: Highway 36 to Superior/Broomfield Boundary ................................ 7-77 7.5.41 Rock Creek Reach 51: Superior/Broomfield Boundary to Irrigation Structure .................... 7-78 7.5.42 Rock Creek Reach 52: Irrigation Structure to Superior/Boulder County Boundary ............. 7-80 7.5.43 Rock Creek Reach 53: Superior/Boulder County Boundary to Upstream Study Limit ......... 7-81

7.6 Prioritizing and Phasing ..................................................................................................................... 7-82 7.7 Water Quality Impacts ....................................................................................................................... 7-82 7.8 Environmental and Safety Assessment ............................................................................................. 7-82 7.9 Operation and Maintenance ............................................................................................................. 7-82 7.10 General Recommendations ............................................................................................................... 7-82

Section 8 References ............................................................................................ 8-1

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List of Tables

Table ES.4-1 Comparison of Peak Flows to Previous Studies ......................................................................... ES-4 Table ES.7-1 Conceptual Design Improvement Cost Estimate Summary by Reach ........................................ ES-7 Table ES.7-2 Conceptual Design Improvements Cost Estimate Summary by Jurisdiction.............................. ES-8 Table 2-1 Existing Land Use Imperviousness Values ........................................................................................ 2-2 Table 2-2 Future Land Use Imperviousness Values ......................................................................................... 2-2 Table 3.2-1 Point Rainfall Depths ..................................................................................................................... 3-1 Table 3.2-2 Rainfall Area Correction Factors ................................................................................................... 3-1 Table 3.3-1 Horton Infiltration Properties ....................................................................................................... 3-2 Table 3.6-1 Comparison of Peak Flows to Previous Studies ............................................................................ 3-3

Table 4-1 Roadway Culvert Overtopping Criteria ............................................................................................ 4-1 Table 4-2 Roadway and Trail Crossing Summary ............................................................................................. 4-3 Table 5.5-1 Unit Costs ...................................................................................................................................... 5-5 Tables 5.6.1-1 to 5.6.43-1 Reach Characteristics ............................................................................... 5-15 to 5-45 Tables 5.6.1-2 to 5.6.43-2 Alternatives Cost Summary ..................................................................... 5-15 to 5-45 Table 5.7-1 Benefit Rating System for Alternatives ...................................................................................... 5-46 Table 5.7-2 Alternatives Summary Evaluation Matrix ................................................................................... 5-47

Table 6-1 Recommended Plan Cost Estimate .................................................................................................. 6-1

Table 7.3.3-1 Reach Average Velocity and Shear Stress Characteristics ......................................................... 7-5 Table 7.3.3-2 Literature Review of Bioengineering Methods .......................................................................... 7-6 Table 7.3.3-3 Bioengineering Methods Reach Applicability ............................................................................ 7-7 Table 7.4-1 Conceptual Design Improvements Cost Estimate Summary by Jurisdiction ................................ 7-8 Tables 7.5.1-1 to 7.5.43-1 Reach Cost Estimates ............................................................................... 7-14 to 7-81

List of Figures

Figure ES-1 Study Area .................................................................................................................................... ES-2 Figure ES-2 Conceptual Design: Reaches 1-11 ................................................................................................ ES-9 Figure ES-3 Conceptual Design: Reaches 12-27, 40-48 ................................................................................. ES-10 Figure ES-4 Conceptual Design: Reaches 28-33 ............................................................................................ ES-11 Figure ES-5 Conceptual Design: Reaches 49-53 ............................................................................................ ES-12 Figure 2-1 Project Area Map ............................................................................................................................ 2-6 Figure 5.6-1 Reach Alternate Figure: Reaches 1-6 ........................................................................................... 5-7 Figure 5.6-2 Reach Alternate Figure: Reaches 7-12 ......................................................................................... 5-8 Figure 5.6-3 Reach Alternate Figure: Reaches 13-23, 40-44 ........................................................................... 5-9 Figure 5.6-4 Reach Alternate Figure: Reaches 24-27 ..................................................................................... 5-10 Figure 5.6-5 Reach Alternate Figure: Reaches 28-31 ..................................................................................... 5-11 Figure 5.6-6 Reach Alternate Figure: Reaches 32-33 ..................................................................................... 5-12 Figure 5.6-7 Reach Alternate Figure: Reaches 45-50 ..................................................................................... 5-13 Figure 5.6-8 Reach Alternate Figure: Reaches 50-53 ..................................................................................... 5-14

Figure 6-1 Recommended Plan Figure: Reaches 1-6 ........................................................................................ 6-3 Figure 6-2 Recommended Plan Figure: Reaches 7-12 ...................................................................................... 6-4 Figure 6-3 Recommended Plan Figure: Reaches 13-23, 40-44 ......................................................................... 6-5 Figure 6-4 Recommended Plan Figure: Reaches 24-27 .................................................................................... 6-6 Figure 6-5 Recommended Plan Figure: Reaches 28-31 .................................................................................... 6-7 Figure 6-6 Recommended Plan Figure: Reaches 32-33 .................................................................................... 6-8 Figure 6-7 Recommended Plan Figure: Reaches 45-50 .................................................................................... 6-9 Figure 6-8 Recommended Plan Figure: Reaches 50-53 .................................................................................. 6-10

Figure 7.5-1 Major Drainageway Plan Schematic Reach 1-11 .......................................................................... 7-9 Figure 7.5-2 Major Drainageway Plan Schematic Reach 12-27, 40-48 ........................................................... 7-10 Figure 7.5-3 Major Drainageway Plan Schematic Reach 28-33 ...................................................................... 7-11 Figure 7.5-4 Major Drainageway Plan Schematic Reach 49-53 ...................................................................... 7-12 Figure 7.5.1-1 Pipeline Crossing and Existing Drop Structure at Station 23+00 on Reach 1 .......................... 7-13 Figure 7.5.1-2 Meander Cutting Into Crop Land at Station 38+00 on Reach 1 .............................................. 7-14 Figure 7.5.2-1 Bank Erosion Cutting Towards Residential Structures at Richards Court on Reach 2 ............. 7-15 Figure 7.5.5-1 Existing Drop Structure Upstream of Briggs Street on Reach 5 .............................................. 7-20 Figure 7.5.7-1 Scour from 2013 Flood at Station 260+00 on Reach 7 ............................................................ 7-23 Figure 7.5.8-1 Incised Meanders on Reach 8.. ................................................................................................ 7-25 Figure 7.5.10-1 Xcel Natural Gas Pipeline in Reach 10 ................................................................................... 7-28 Figure 7.5.10-2 Cottonwood Extension Ditch Diversion Structure and Pedestrian Bridge on

Reach 10 Before and After 2013 Flood .............................................................................................. 7-28 Figure 7.5.11-1 Channel Meander Threatening Buildings at Erie Municipal Airport in Reach 11 .................. 7-30 Figure 7.5.12-1 Typical Cross Section for Reach 12 Overbank Conveyance Improvements .......................... 7-32 Figure 7.5.13-1 Channel Bank Erosion Next to Flagg Drive Caused by 2013 Flood ........................................ 7-34 Figure 7.5.17-1 Residential Structure in Reach 21 Next to Coal Creek and South 120th Street .................... 7-39 Figure 7.5.18-1 Typical Reach 22 Overbank Conveyance Improvements Cross Section ................................ 7-41 Figure 7.5.19-1 Channel Bank Erosion on Reach 23 in Warembourg-Lafayette

Farm Caused by 2013 Flood ….. ......................................................................................................... 7-43 Figure 7.5.21-1 Channel Realignment and Bank Erosion on Reach 25 Caused by 2013 Flood ...................... 7-47 Figure 7.5.21-2 Typical Cross Section for Reach 25 Overbank Conveyance Improvements .......................... 7-47 Figure 7.5.22-1 Channel Realignment and Bank Erosion Upstream of Empire Drive

Caused by 2013 Flood ........................................................................................................................ 7-48 Figure 7.5.22-2 Bank Erosion and Scour Downstream of Empire Road Caused by 2013 Flood

at Station 914+00............................................................................................................................... 7-49 Figure 7.5.23-1 Reach 27 Channel Realignment Caused by 2013 Flood ........................................................ 7-50 Figure 7.5.25-1 Station 1080+00 Before and After 2013 Flood ...................................................................... 7-54 Figure 7.5.27-1 Station 1121+00 on Coal Creek Before and After 2013 Flood .............................................. 7-57 Figure 7.5.28-1 During the 2013 Flood, the Channel in Reach 32 Realigned Itself up to 160 Feet

Northwest of the Original Channel .................................................................................................... 7-59 Figure 7.5.29-1 Aerial Image of 1,700-Foot-Long Channel Realignment in Reach 33

Caused by 2013 Flood ........................................................................................................................ 7-61 Figure 7.5.30-1 Incised Meanders on Reach 40.............................................................................................. 7-63 Figure 7.5.30-2 Typical Cross Section for Reach 40 Overbank Conveyance Improvements .......................... 7-64 Figure 7.5.33-1 Damage to Drainageway G Channel Banks Caused by Rock Creek in Reach 43 ................... 7-68 Figure 7.5.35-1 Dillon Road Frontage Road Culvert That Failed During 2013 Flood ...................................... 7-70 Figure 7.5.41-1 Incised Channel Banks Approaching Recreation Path and Pump Track ................................ 7-78

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APPENDICES

Appendix A Project Correspondence

Meeting Minutes Focus Meeting .................................................................................................................................. May 11, 2012 Kickoff Meeting ................................................................................................................................ May 23, 2012 Progress Meeting ............................................................................................................................ June 18, 2012 Progress Meeting .............................................................................................................................. July 23, 2012 Progress Meeting ......................................................................................................................... August 27, 2012 Conceptual Design Kickoff Meeting. ................................................................................................ May 12, 2014 120th Street Improvements Meeting .............................................................................................. June 18, 2014 Final Progress Meeting ......................................................................................................... September 11, 2014

Review Comments Draft Hydrology Review Comments ............................................................................................. August 24, 2012 Draft Alternatives Report Review Comments ........................................................................ November 25, 2013 Final Alternatives Report Review Comments ................................................................................. April 29, 2014 Draft Major Drainageway Plan Comments ......................................................................................... July 7, 2014 Selected Plan for the Coal Creek and Rock Creek MDP Letter ........................................................ April 29, 2014

Appendix B Hydrologic Analysis

Figure B-1 Hydrology Map Figure B-2 Existing Peak Flow Profile – Lower Coal Creek Figure B-3 Existing Peak Flow Profile – Upper Coal Creek Figure B-4 Existing Peak Flow Profile – Rock Creek Figure B-5 Future Peak Flow Profile – Lower Coal Creek Figure B-6 Future Peak Flow Profile – Upper Coal Creek Figure B-7 Future Peak Flow Profile – Rock Creek Figure B-8 Coal Creek Existing Land Use Hydrograph Figure B-9 Rock Creek Existing Land Use Hydrograph Figure B-10 Coal Creek and Rock Creek near the Confluence Existing Land Use Hydrograph Figure B-11 Coal Creek Future Land Use Hydrograph Figure B-12 Rock Creek Future Land Use Hydrograph Figure B-13 Coal Creek and Rock Creek near the Confluence Future Land Use Hydrograph Table B-1 Number Correlation Between 2006 and 2013 Studies Kiowa (2006 Study) Routing Map Table B-2 Future Land Use Table B-3 CUHP Subwatershed Characteristics Table B-4 SWMM Model Input & Sample Output Table B-5 Peak Flow Summary Table B-6 Boulder County One-Hour Point Rainfall Table B-7 Boulder County Six-Hour Point Rainfall Table B-8 Jefferson County Zone 2A One-Hour Point Rainfall Table B-9 Jefferson County Zone 2A Six-Hour Point Rainfall Table B-10 Jefferson County Zone 2B One-Hour Point Rainfall

Table B-11 Jefferson County Zone 2B Six-Hour Point Rainfall

Appendix C Hydraulic Analysis

Figure C-1 Study Reaches and Identified Problem Areas: Reaches 1-12 Figure C-2 Study Reaches and Identified Problem Areas: Reaches 13-27 Figure C-3 Study Reaches and Identified Problem Areas: Reaches 28-33 Figure C-4 Study Reaches and Identified Problem Areas: Reaches 40-50 Figure C-5 Study Reaches and Identified Problem Areas: Reaches 51-53

Appendix D Legal Description

Appendix E Wetland and Riparian Inventory

Figure E-1 ............................................................................. Possible Wetland and Riparian Zones: Reaches 1-6 Figure E-2 ........................................................................... Possible Wetland and Riparian Zones: Reaches 7-12 Figure E-3 ............................................................. Possible Wetland and Riparian Zones: Reaches 13-23, 40-44 Figure E-4 ......................................................................... Possible Wetland and Riparian Zones: Reaches 24-27 Figure E-5 ......................................................................... Possible Wetland and Riparian Zones: Reaches 28-31 Figure E-6 ......................................................................... Possible Wetland and Riparian Zones: Reaches 32-33 Figure E-7 ......................................................................... Possible Wetland and Riparian Zones: Reaches 45-50 Figure E-8 ......................................................................... Possible Wetland and Riparian Zones: Reaches 50-53

Appendix F Alternatives Analysis

Table F-1 Alternative Screening Matrix

Appendix G Conceptual Design Information

Figure G-1 Example Hard Stream Stability Measures Figure G-2 Example Bioengineered Stream Stability Measures Figure G-3 Example Bioengineered (Soft) Stream Stabilization Techniques Improvements to Coal Creek Upstream of McCaslin Blvd – Overall Site Plan

Appendix H Master Plan Maps

Appendix I Master Plan Profiles

EXECUTIVE SUMMARY

ES-1


The Conceptual Design for the Major Drainageway Plan for the Coal Creek and Rock Creek Drainageway is presented

herein, in the Coal Creek and Rock Creek Major Drainageway Plan. On June 17, 2012, Boulder County, the City and

County of Broomfield, the Town of Erie, the City of Lafayette, the City of Louisville, and the Town of Superior

partnered with the Urban Drainage and Flood Control District (UDFCD) to initiate a master plan for the Coal Creek

and Rock Creek watershed.

This Conceptual Design Report presents the Conceptual Design that was selected from the alternatives developed

for the Coal Creek and Rock Creek study area within the City and County of Broomfield, the Town of Erie, the City of

Lafayette, the City of Louisville, the Town of Superior, and unincorporated Boulder County. The objectives of this

study are to evaluate the existing drainage concerns within the study area along with the adequacy of the existing

drainage structures, including channels, culverts, and bridges. Based on this evaluation, improvements were

selected to alleviate drainage and flooding problems along Coal Creek and Rock Creek. The Conceptual Design

integrates flood conveyance, stormwater quality, channel stability, erosion control, and aesthetics into one drainage

master planning document.

This report provides conceptual plan maps, profile drawings, cost estimates, and an implementation plan for the

selected drainage improvements.

ES.1 PURPOSE AND OBJECTIVES

The purpose of the study is to supply a master plan for the Coal Creek and Rock Creek watershed that provides

guidance to the project sponsors for future construction projects and development plans. The objectives of the

study are to evaluate the existing drainage concerns on Coal Creek and Rock Creek and to develop conceptual plans

to provide the safe and economic conveyance of stormwater runoff while minimizing the risk of loss of life and

major property damage. The scope of this study specifies that the baseline hydrology will be evaluated for the

entire Coal Creek and Rock Creek watershed. However, the alternatives evaluation, analysis of future facilities, and

recommendation of improvements (for roadway crossings and channels) only addresses the major drainageways

(i.e. Coal Creek and Rock Creek).

The Major Drainageway Planning Study (MDP) includes three phases: the Baseline Hydrology Phase was completed

in September 2012, the Alternatives Evaluation Phase was completed in March 2014, and the Conceptual Design

Phase for which this Conceptual Design Report is published. The project also includes a Digital Flood Hazard Area

Delineation (DFHAD), which was developed concurrently with the Alternatives Evaluation Phase.

ES.2 PLANNING PROCESS

The planning effort for this project began in June 2012. Since that time, a series of progress meetings has taken

place to exchange information, discuss ideas and findings, and present results during each phase of the study.

Numerous stakeholders, including representatives from Boulder County, the City and County of Broomfield, the

Town of Erie, the City of Lafayette, the City of Louisville, the Town of Superior, and the UDFCD, have attended the

progress meetings to participate in the planning process.

The following individuals, representing the project sponsors, have attended the progress meetings and given input

to the study:

Shea Thomas Urban Drainage and Flood Control District Ken MacKenzie Urban Drainage and Flood Control District Dave Skuodas Urban Drainage and Flood Control District Claire DeLeo Boulder County Justin Gindlesperger Boulder County Mike Thomas Boulder County Rebecca Baker City and County of Broomfield Wendi Palmer Town of Erie Gary Hegner Town of Erie Peter Johnson City of Lafayette Jeff Moline City of Lafayette David Thompson City of Louisville Cameron Fowlkes City of Louisville Alex Ariniello Town of Superior Lisa Ritchie Town of Superior David Heinrich Town of Superior

In addition to the meetings, a project website was created to inform the public of the progress of the study and

gather input on specific issues. The website provides project information, notices for upcoming meetings, meeting

minutes, study reports, and contact information. The website can be accessed at http://www.coalrock.com.

http://www.coalrock.com/

ERIE

SUPERIOR

LOUISVILLE

LAFAYETTE

COALCREEK

BROOMFIELD

CREEK

ROCK

UDFCD BOUNDARY

UDFC

D BOU

NDAR

Y

BOULDERCOUNTYSTUDY LIMIT

STUDYLIMIT

CREE

KCO

AL

BOULDERCOUNTY

WELDCOUNTY

36

Coal CreekWatershed Boundary

Coal CreekWatershed Boundary

Urban Drainage and Flood Control District,Boulder County, City and County of Broomfield, Town of Erie,

City of Lafayette, City of Louisville, Town of Superior

0 1 2 30.5 Miles

³Project Area Map

720 S. Colorado Blvd.Suite 410 SDenver, CO 80246(303) 757-3655(303) 300-1635 (fax)www.respec.com

ProjectLimits

Figure ES-1Coal Creek and Rock CreekMajor Drainageway Planning Study

DesignedDrawnCheckedRevised

DateDateDateDate

128

W. 120th Ave.

EXECUTIVE SUMMARY

ES-3


ES.3 PROJECT AREA

The project area consists of the Coal Creek and Rock Creek watershed, which is located within Weld County, the City

and County of Broomfield, Boulder County, Jefferson County, and Gilpin County. The entire Coal Creek and Rock

Creek watershed is 80 square miles or 51,000 acres. The study limits for the Coal Creek and Rock Creek Major

Drainageway Plan begin on the south downstream of Highway 128 (West 120th Avenue) for both Coal Creek and

Rock Creek and end at the confluence with Boulder Creek. The study area is illustrated in Figure ES-1.

Beginning at the downstream study limit near the confluence of Boulder Creek and Coal Creek and moving

upstream, Coal Creek flows through Erie and crosses under Kenosha Road, East County Line Road, Briggs Street,

Cheesman Street, Erie Parkway, Vista Parkway, and an Erie Airport taxiway. It then passes through Lafayette and

under East Baseline Road. Moving upstream, Coal Creek continues south through Boulder County Open Space to the

confluence with Rock Creek, which is in Lafayette. Upstream of the confluence, Coal Creek heads west, meandering

in and out of Lafayette and unincorporated Boulder County and crossing under South 120th Street, South Public

Road, and Highway 287. Once in Louisville, Coal Creek heads southwest, crossing under Empire Drive, Empire Road,

North 96th Street, the railroad, and County Road; through the Coal Creek Golf Course; and under West Dillon Road.

After crossing Highway 36, Coal Creek continues southwest through Superior, crossing McCaslin Boulevard and

South 2nd Avenue. Upstream of Superior, Coal Creek continues southwest through unincorporated Boulder County

toward the study limit at Highway 128 (West 120th Avenue). Beyond the study limit, Coal Creek continues westerly

into the foothills of Boulder County and Jefferson County before summiting at Thorodin Mountain in Gilpin County.

Beginning at the confluence with Coal Creek moving upstream, Rock Creek starts in Lafayette, heading southwest

and crossing under Horizon Avenue and South 120th Street. It traverses through a small portion of unincorporated

Boulder County and then through Broomfield, where is crosses four Northwest Parkway Bridges. Rock Creek then

reenters unincorporated Boulder County, crossing under Dillon Road and Highway 287 and continuing through the

Carolyn Holmberg Preserve at Rock Creek Farm. Rock Creek continues upstream, crossing under South 104th Street

through a short section of Broomfield before crossing under Carbon Road and reentering unincorporated Boulder

County. At the Brainard Drive crossing, Rock Creek reenters Broomfield and continues southwest, crossing under

West Midway Boulevard, Storage Tek Drive, and Highway 36; through the Flatiron Crossing Mall; and under West

Flatiron Crossing Drive. From there, Rock Creek continues upstream west through Superior, crossing under Rock

Creek Parkway, South Indiana Street, Coalton Road, and McCaslin Boulevard. The remaining portion of the study

limit at Highway 128 (West 120th Avenue) is through unincorporated Boulder County, which is comprised of open

space preserved for grassland prairie, recreation, and grazing for livestock. Rock Creek continues southwest into the

foothills of Jefferson County originating in the Rocky Flats National Wildlife Refuge.

General watershed characteristics include:

• Highest watershed elevation (approximate) = 10,500 feet

• Lowest watershed elevation (approximate) = 4,900 feet

• Average slope of channel = 0.0164 feet/foot on Coal Creek

• Average slope of channel = 0.0107 feet/foot on Rock Creek

• Watershed shape (length/width) = 7

While this study was underway, the northern front range of Colorado was impacted by record flooding as the result

of heavy rain from September 9–15, 2013. While the Coal Creek and Rock Creek drainages did not see the same

heavy rains as Boulder County to the northwest and the Sand Creek area to the southeast, the area still received

significant damage from floodwater. Section 2.4 has a detailed description of damage within the study area caused

by the 2013 flood. This report partially addresses damage caused by the 2013 flood as well as proactive measures to

protect against future floods; however, extensive documentation and flood recovery recommendations are beyond

the scope of this study.

ES.4 HYDROLOGIC ANALYSIS

The purpose of the hydrology analysis was to update the hydrology for the Coal Creek and Rock Creek watershed.

The main drainageways in the study area are Coal Creek and Rock Creek. Previous hydrology for the area was

developed in the 1976 United States Department of Agriculture Soil Conservation Service (USDA-SCS) study, which is

the effective Federal Emergency Management Agency (FEMA) hydrology in the local Flood Insurance Study (FIS).

Additionally, the area of the Coal Creek watershed upstream of Highway 36 was studied in the 2006 Coal Creek

(Through Town of Superior) Major Drainageway Planning Study (2006 MDP) that published updated hydrology for

the upper portions of Coal Creek.

The 2006 MDP hydrology model files were provided by UDFCD for incorporation into the current study’s hydrology

models. The storm runoff hydrographs and routing for the study were generated using Colorado Urban Hydrograph

Procedure (CUHP) 2005 Version 1.3.3 and the Environmental Protection Agency (EPA) Stormwater Management

Model (SWMM) Version 5.0 Build 5.0.022. A comparison of peak flows for existing and future land use and from

previous studies is shown in Table ES.4-1.

EXECUTIVE SUMMARY

ES-4


Table ES.4-1. Comparison of Peak Flows to Previous Studies

Existing LU Future LU1050 Coal Creek Briggs Street 12,280 11,100 12,600 1062 Coal Creek RTD Rail Line Near Erie 12,250 11,200 12,600 1210 Coal Creek Near Erie Municipal Airport 11,850 11,300 12,700 1502 Coal Creek Below Confluence With Rock Creek 10,640 11,100 12,400 1520 Coal Creek U.S. Highway 287 4,110 4,610 4,930 1600 Coal Creek Lafayette/Louisville City Limits 4,040 4,310 4,650 1620 Coal Creek Burlington Northern Railroad 4,120 3,620 3,640 3000 Coal Creek Denver Boulder Turnpike (Hwy 36) 3,820 3,927 3,660 3,680 3020 Coal Creek McCaslin Boulevard 3,770 3,827 3,640 3,670 5000 Rock Creek Confluence With Coal Creek 6,690 7,880 9,870 5010 Rock Creek South 120th Street 6,740 7,980 10,100 5030 Rock Creek Downstream Corporate Limits 6,710 7,570 9,580 5040 Rock Creek Dillon Road / NW Parkway 6,500 6,100 7,630 5100 Rock Creek U.S. Highway 287 5,880 7,380 5110 Rock Creek South 104th Street 4,040 4,910 5500 Rock Creek Denver Boulder Turnpike (Hwy 36) 4,520 3,220 3,720 5530 Rock Creek McCaslin Boulevard 2,717 1,500 1,520

* FIS flows are the same as those published in the 1976 USDA SCS Study

DesignPoint FIS*

2006Future LU

2012Drainageway

100-Year Peak Flow (cfs)

Location

ES.5 HYDRAULIC ANALYSIS

The Coal Creek and Rock Creek hydraulic analysis modeling was performed using the U.S. Army Corps of Engineers’

HEC-RAS Version 4.1.0. The results of the modeling indicated three flow splits, numerous buildings within the 100-

year floodplain, and eight hydraulic structures at major road crossings that do not convey the 100-year discharge

and are recommended for replacement. The Kenosha Road, 120th Street, and Empire Drive bridges over Coal Creek

are overtopped in 50-year and greater events. The structure at the County Road and Coal Creek crossing was

overtopped in the 50-year event and failed during the 2013 flood. The 2nd Avenue bridge over Coal Creek is

overtopped in the 100-year event. The structure at the Horizon Avenue and Rock Creek crossing is overtopped in the

10-year event. The 120th Street bridge over Rock Creek is overtopped in 50-year and greater events. The culvert at

the Dillon Frontage Road and Rock Creek crossing was overtopped in the 10-year event and received national media

attention when it washed out in the 2013 flood. In addition to the eight structures at major crossings, there are

multiple structures on lesser roads that are overtopped in the 100-year event that are not recommended for

replacement.

Structures and buildings within the 100-year floodplain are clustered within five primary locations. Within Reach 1 in

the Westview Estates area, 85 buildings are inundated by the 100-year event. In Reach 5, backwater from Coal Creek

places 106 structures within the 100-year

floodplain. At the Coal Creek and Rock Creek

confluence, 16 commercial and industrial

buildings are within the 100-year floodplain.

Upstream of McCaslin Boulevard in the Town of

Superior in Reach 30, 24 buildings are inundated

by floodwaters during the 100-year event. In

Reach 26 on the Rock Creek Farm, 19 buildings

are within the 100-year floodplain. Throughout

the study area, there are a total of 280 buildings

in the 100-year floodplain.

ES.6 ALTERNATIVES EVALUATION

The Alternatives Evaluation Phase began with a brief consideration of many possible solutions to the drainage

concerns in the Coal Creek and Rock Creek study area. The objective of the investigation was to approach the

identification of potential alternatives in a broad and complete manner and to ensure that all feasible solutions were

considered.

Five alternative categories were considered for the initial screening of alternative plans for each reach of Coal Creek

and Rock Creek.

1. Floodplain Preservation – Preserves the 100-year floodplain in its current location to conserve the land and

existing habitat and to protect against encroachments and degradation.

2. Floodway Preservation – Preserves the existing floodway and allows fill and development in the floodplain

fringe.

3. Overbank Conveyance Improvements – Channel improvements in the overbanks provide additional

conveyance as an effort to safely convey 100-year flood flows and modify the floodplain boundary.

4. Limited Structural Improvements – Assumes that the drainageway is generally in good condition, but needs

limited improvements to address localized problem areas.

5. Regional Detention – Detention facilities that are publicly owned and maintained are implemented to

reduce downstream peak flows.

Dillon Frontage Road culvert during the 2013 flood

EXECUTIVE SUMMARY

ES-5


The above categories address approaches to channel maintenance, flood conveyance, and reduced peak flows

through regional detention. Some of the alternatives take a reactive approach to fixing problems in the

drainageways by addressing existing observed problems or plans to address channel instabilities as they develop.

Most take a more proactive approach by implementing stability and protective measures prior to the degradation of

the channel banks and thalweg.

During the Alternatives Evaluation Phase, it became apparent that regional detention would be ineffective within

the study area. Predicted footprint and feasible depths were modeled for locations conducive to detention. The

models showed that the reduction in peak flows from detention was minimal and did not yield a substantial

reduction in floodplain width or structure replacement requirements. Because of this, regional detention was

abandoned during the Alternatives Evaluation Phase in favor of other alternatives and was not utilized in the

conceptual design.

An initial screening matrix was developed to compare the various alternatives on the basis of probable costs,

feasibility, and environmental impacts. This matrix determined that the best alternatives for all reaches of Coal

Creek and Rock Creek were the floodplain preservation, floodway preservation, overbank conveyance

improvements, and limited structural improvements categories.

ES.7 RECOMMENDED PLAN

The lower portions of the Coal Creek and Rock Creek watershed are primarily developed and are showing signs of

stream instability caused by increased runoff from development and wastewater treatment plant effluent.

Therefore, many of the master plan’s recommendations address preventative and proactive measures to mitigate

future erosion. Development not only increases the peak flows, but also increases the total runoff volume. This

increase in peak flows and volume has shown to cause the majority of damage from frequent storm events. By

installing drainage structures that stabilize the stream beds and channel banks, the waterways are less likely to

migrate, erode, yield water quality issues, or cause maintenance problems.

The recommended plan takes a conservative, preventative approach to management of the drainageway. In

general, the recommendations target preserving the floodplains, preserving the floodways, maintaining the existing

engineered channels, or providing increased conveyance. Lateral channel stability is improved by utilizing both hard

(rock) and soft (bioengineered) methods to prevent channel bank erosion and repair existing erosion. Vertical

channel stability is improved by using checks and drop structures to prevent head cutting. In areas where insurable

structures are within the 100-year floodplain, as defined by the 2014 DFHAD, the improvements attempt to either

decrease the flood elevations or target the properties for acquisition to remove the flood risk from the owner.

ES.8 SELECTED PLAN AND CONCEPTUAL DESIGN

The project sponsors picked the selected plan from the recommended plan for the Conceptual Design Phase of the

project. The selected plan mirrors the suggestions in the recommended plan.

The conceptual design generally follows the indications of the selected plan; however, during the development of

the design, a few additional modifications were made.

• During the Conceptual Design Phase, it was discovered that overbank flows during the 100-year event

threatened to overtop 120th Street south of the bridge regardless of structural improvements. Overbank

conveyance improvements in this reach in conjunction with the road crossing upgrade channelized flood

flows, preventing them from overtopping 120th Street, and remove all buildings along the reach from the

100-year floodplain. Because of this, the proposed design was changed from floodway preservation to

overbank conveyance improvements.

• The portion of Reach 40 downstream of station 2024+00 is completely within open space land and

undeveloped. The proposed design for Reach 40 was changed to floodplain preservation downstream of

station 2024+00 and remains overbank conveyance improvements in the upstream portion of the reach.

• The selected plan for Reach 45, overbank conveyance improvements, was ineffective at removing all

insurable structures from the 100-year floodplain and required significant modifications to the channel and

overbanks. These modifications are undesirable on the open space land that comprises much of the reach.

Furthermore, floodway preservation allows all insurable structures to be removed from the floodplain

during redevelopment by the application of additional fill. Because of these factors, the proposed design in

Reach 45 was changed to floodway preservation.

• Overbank conveyance improvements in Reach 46 were ineffective at removing the Rock Creek Farm

structures from the 100-year floodplain. The structures are also within the 2014 DFAHD floodway. Because

of this, the proposed design for Reach 46 was changed to floodplain preservation. An area of localized fill is

still proposed upstream of Highway 287 in the left overbank to prevent shallow flooding from inundating the

southbound lanes of the highway and Dillon Road.

The resulting conceptual design is a combination of floodplain/floodway preservation, conveyance improvements,

roadway crossing structure upgrades, and stream stabilization measures. The conceptual design removes 18 of 280

buildings from the 100-year floodplain. Preliminary estimates for capital improvement costs as well as annual

operation and maintenance were developed in greater detail than those in the Alternatives Evaluation Phase. See

Figures ES-2 through ES-5 for an overview of the conceptual design improvements.

EXECUTIVE SUMMARY

ES-6


The phasing and prioritization of the conceptual design improvements are largely dependent on the sequence of

development in the watershed. It is recommended that the local jurisdictions give special attention to changes in

hydrology as the watershed land uses become more impervious.

Table ES.7-1 lists the approximate costs of implementing the conceptual design by reach and Table ES.7-2 totals the

approximate costs by jurisdiction. The cost estimate was developed using the UDFCD Cost Estimator for Master

Planning Version 2.1. The cost estimate is further refined from the costs developed during the Alternatives

Evaluation Phase; however, it is still preliminary in nature. Conceptual design maps and profiles illustrate the

proposed improvements and are located in Appendices H and I, respectively. For detailed cost estimates, see the

respective reach discussion in Section 7.5.

EXECUTIVE SUMMARY

ES-7


Table ES.7-1. Conceptual Design Improvement Cost Estimate Summary by Reach

REACH CAPITAL EASEMENT/ ROW ENGINEERING LEGAL/ ADMINISTRATIVE

CONTRACT ADMIN/CM CONTINGENCY TOTAL CAPITAL

COST

Reach 1 $4,400,000 $0 $660,000 $220,000 $440,000 $1,100,000 $6,820,000Reach 2 $2,144,000 $0 $322,000 $107,000 $214,000 $536,000 $3,323,000Reach 3 $335,000 $0 $50,000 $17,000 $33,000 $84,000 $519,000Reach 4 $310,000 $0 $47,000 $16,000 $31,000 $78,000 $481,000Reach 5 $21,000 $0 $3,000 $1,000 $2,000 $5,000 $33,000Reach 6 $36,000 $0 $5,000 $2,000 $4,000 $9,000 $56,000Reach 7 $456,000 $0 $68,000 $23,000 $46,000 $114,000 $707,000Reach 8 $634,000 $0 $95,000 $32,000 $63,000 $158,000 $982,000Reach 9 $681,000 $0 $102,000 $34,000 $68,000 $170,000 $1,056,000

Reach 10 $1,034,000 $0 $155,000 $52,000 $103,000 $259,000 $1,603,000Reach 11 $3,259,000 $0 $489,000 $163,000 $326,000 $815,000 $5,052,000Reach 12 $2,468,000 $0 $370,000 $123,000 $247,000 $617,000 $3,825,000Reach 13 $878,000 $0 $132,000 $44,000 $88,000 $219,000 $1,361,000Reach 14 $469,000 $35,000 $70,000 $23,000 $47,000 $117,000 $761,000Reach 15 $139,000 $0 $21,000 $7,000 $14,000 $35,000 $216,000Reach 20 $58,000 $0 $9,000 $3,000 $6,000 $15,000 $90,000Reach 21 $65,000 $0 $10,000 $3,000 $7,000 $16,000 $101,000Reach 22 $5,949,000 $56,000 $892,000 $297,000 $595,000 $1,487,000 $9,277,000Reach 23 $685,000 $0 $103,000 $34,000 $68,000 $171,000 $1,061,000Reach 24 $376,000 $0 $56,000 $19,000 $38,000 $94,000 $583,000Reach 25 $1,641,000 $0 $246,000 $82,000 $164,000 $410,000 $2,543,000Reach 26 $4,615,000 $266,000 $692,000 $231,000 $461,000 $1,154,000 $7,419,000Reach 27 $3,755,000 $0 $563,000 $188,000 $376,000 $939,000 $5,821,000Reach 28 $1,715,000 $0 $257,000 $86,000 $172,000 $429,000 $2,659,000Reach 29 $327,000 $0 $49,000 $16,000 $33,000 $82,000 $507,000Reach 30 $1,458,000 $0 $0 $0 $0 $0 $1,458,000Reach 31 $255,000 $0 $38,000 $13,000 $26,000 $64,000 $395,000Reach 32 $65,000 $288,000 $10,000 $3,000 $6,000 $16,000 $388,000Reach 33 $0 $0 $0 $0 $0 $0 $0Reach 40 $9,830,000 $0 $1,474,000 $491,000 $983,000 $2,457,000 $15,236,000Reach 41 $12,636,000 $0 $1,895,000 $632,000 $1,264,000 $3,159,000 $19,585,000Reach 42 $223,000 $19,000 $34,000 $11,000 $22,000 $56,000 $366,000Reach 43 $179,000 $0 $27,000 $9,000 $18,000 $45,000 $277,000Reach 44 $0 $0 $0 $0 $0 $0 $0Reach 45 $892,000 $0 $134,000 $45,000 $89,000 $223,000 $1,383,000Reach 46 $158,000 $0 $24,000 $8,000 $16,000 $39,000 $245,000Reach 47 $62,000 $0 $9,000 $3,000 $6,000 $16,000 $97,000Reach 48 $0 $0 $0 $0 $0 $0 $0Reach 49 $429,000 $0 $64,000 $21,000 $43,000 $107,000 $664,000Reach 50 $279,000 $0 $42,000 $14,000 $28,000 $70,000 $432,000Reach 51 $131,000 $0 $20,000 $7,000 $13,000 $33,000 $203,000Reach 52 $43,000 $0 $6,000 $2,000 $4,000 $11,000 $67,000Reach 53 $0 $0 $0 $0 $0 $0 $0

Totals $63,090,000 $664,000 $9,245,000 $3,082,000 $6,163,000 $15,408,000 $97,651,000

EXECUTIVE SUMMARY

ES-8


Table ES.7-2. Conceptual Design Improvements Cost Estimate Summary by Jurisdiction

JURISDICTION CAPITAL EASEMENT / ROW* ENGINEERING LEGAL /

ADMINISTRATIVECONTRACT ADMIN/CM CONTINGENCY TOTAL

CAPITAL COSTTOTAL CAPITAL MINUS

EASEMENT / ROW

Town of Erie $8,910,000 $0 $1,336,000 $447,000 $890,000 $2,228,000 $13,812,000 $13,812,000

City of Lafayette $33,320,000 $75,000 $4,997,000 $1,665,000 $3,333,000 $8,330,000 $51,721,000 $51,646,000

City of Louisville $10,085,000 $266,000 $1,512,000 $505,000 $1,009,000 $2,522,000 $15,899,000 $15,633,000

Boulder County $8,108,000 $323,000 $1,217,000 $405,000 $811,000 $2,026,000 $12,889,000 $12,566,000

Town of Superior $1,959,000 $0 $75,000 $25,000 $50,000 $126,000 $2,235,000 $2,235,000

City and County of Broomfield $708,000 $0 $106,000 $35,000 $71,000 $177,000 $1,096,000 $1,096,000

Totals $63,090,000 $664,000 $9,243,000 $3,082,000 $6,164,000 $15,409,000 $97,652,000 $96,988,000

* Easement / ROW are land values associated with implementing Floodplain Preservation and Overbank Conveyance Improvements

Reach 1(Floodway Preservation)

Reach 2(Limited Structural Improvements)



(Floodway Preservation)Reach 5

Reach 6(Floodplain Preservation)




Reach 10

(Floodway Preservation withOverbank Conveyance Improvements)

Average Width = 400 Ft

Reach 11

(Floodway Preservation)

Coal Creek

Boulder Creek

Coal CreekCoal Creek

Kenosha Rd BridgeProposed: 59' Span

MATCHLIN

E

720 S Colorado Blvd.Suite 410SDenver, CO 80245303-757-3655www.respec.com

Created by: M. BannisterDate: 07/03/2014 Executive Summary

Conceptual DesignFigureES-2

Coal Creek and Rock CreekMajor Drainageway Plan

UDFCD, Boulder County, Erie, Lafayette,Louisville, Superior, and Broomfield

HWY-

287

HWY-36

CO-7/Arapahoe Rd

0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft

City Lines Represent Municipal Boundaries

LegendBroomfieldErieLafayetteLouisvilleSuperior

County LineCity Line100-YearFloodplain

Reach 12(Overbank Conveyance

Improvements)Average Width = 400 Ft


Reach 14(Floodplain Preservation)Reach 15

(Floodplain Preservation)


Reach 21(Floodway Preservation)Reach 22

(Overbank Conveyance Improvements)Average Width = 150 Ft



Reach 25(Overbank Conveyance Improvements

and Localized Fill)Average Width = 390 Ft

Reach 26(Floodplain Preservation)Reach 27

(Floodway Preservation)

Reach 40(Overbank Conveyance Improvements/

Floodplain Preservation)Average Width = 240 Ft




Reach 44(No Improvements)





Coal Creek

Coal Creek

Coal Creek

Rock Creek

Rock Creek

Coal Creek

Rock Creek

Rock Creek

Horizon Ave BridgeProposed: 166' Span

S 120th St BridgeProposed: 124' Span

Empire Drive BridgeProposed: 58.7' Span

Dillon Rd Frontage Rd CulvertPlanned: 3 - 14' x 12' CBC 1 - 16' x 9' CBC

S 120th St BridgeProposed: 134' Span

County Rd BridgeProposed: 58' Span

MATCHLIN

E

MATCHLIN

E

MATC

HLIN

E

MATCHLINEMA

TCHL

INE






HWY-2

87

HWY-36

CO-7/Arapahoe Rd

0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft




0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft

Reach 28(Limited Structural Improvements)


Reach 30(No Improvements)




Rock Creek


Coal Creek

Rock Creek

Rock Creek

2nd Ave CulvertPlanned: Existing Culvert and

Additional 28' 3-Sided Box Culvert

MATC

HLIN

E






HWY-2

87HWY-36

CO-7/Arapahoe Rd

0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft






0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft



Reach 51

(Floodplain Preservation)Reach 52

(Floodplain Preservation)


Rock Creek

Coal Creek


Rock Creek

Rock Creek

MATC

HLIN

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HWY-2

87HWY-36

CO-7/Arapahoe Rd

0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft




0 1,000 2,000 3,000 4,000Feet

1 in = 2,000 ft

coal creek and rock creek major drainageway plan

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