Mountain States Chapter International Erosion Control Association Conference

Transcription

1 Mountain States Chapter International Erosion Control Association Conference November 5, 2015 Ian Paton, P.E, CFM Wright Water Engineers, Inc. Eliot Wong P.E., CFM Contech Engineered Solutions Hayes Lenhart, P.E. Wright Water Engineers, Inc. 1 June 23 July 10, 2012 West of Colorado Springs Source: csdailyphoto.blogspot.com Source: The Denver Post 2 1

2 Waldo Canyon fire boundary (~29 square miles) (red line) Williams Canyon drainage basin (~2.7 square miles) (black line) Manitou Springs Source: Waldo Canyon Fire WARSSS Study 3 Williams Canyon watershed (~ 2.7 square miles) Manitou Springs 4 2

3 Debris and damage after storm on August 9, Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions 6 3

4 Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions 7 Channel filled with debris Before After Williams Canyon north of Highway 24 Before flood events Source: Google Earth Same location after flood event on August 9, 2013 Source: Bob Jarrett, ret. USGS 8 4

5 Several flood events in summer Debris, flooding - Damage to homes, businesses, stormwater infrastructure 9 Bridge at Narrows Road after flood event on August 9,

6 After flood event on August 9, 2013 Near where the Williams Canyon channel meets Canon Ave. 11 Response Involved Public Interaction Manitou Springs Flood Coalition Multiple public meetings Discussion of problems and options Walkdown of Williams Canyon with officials from City, El Paso County, NRCS, CWCB on August 15,

7 Federal NRCS Emergency Watershed Protection (EWP) Program State Colorado Water Conservation Board (CWCB) Department of Local Affairs (DOLA) Colorado Department of Transportation (CDOT) Colorado Office of Emergency Management (OEM) City, Other Sources Total Project Budget: approx. $6.1M 13 City City - Flood Recovery Manager Ensign Engineering Owner s Representative Design Team Wright Water Engineers, Inc. (civil engineer) Kumar and Associates (geotechnical engineer) J.F. Sato and Associates (structural engineer) Clark Surveying Contractor Perco Rock Company 14 7

8 Phase 1 (approx. 1,000 ft) Phase 2 (approx. 480 ft) N 15 Phase 1 (approx. 1,000 ft) Phase 1 - Primary Objectives - Provide for capture of debris - Improve channel capacity/ eliminate constrictions - Improve channel durability N 16 8

9 Phase 2 (approx. 480 ft) Phase 2 - Primary Objectives - Improve channel capacity (through Narrows neighborhood) - Improve channel durability - Transition to existing box culvert N 17 Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions 18 9

10 Reduce impacts from debris to downstream infrastructure Structures, Property Existing downstream stormwater system (box culvert) Large debris source in watershed (from watershed above Phase 1) Debris damage to historic channel and properties 19 Phase 1 area Channel unstable and damaged from debris Limited hydraulic capacity at specific locations Space constraints, including roadway to be preserved and protected from erosion 20 10

11 Phase 2 area Channel damaged and with limited hydraulic capacity Space constraints, existing structures and utilities Transition to existing box culvert 21 Analysis of: Flow WSELs Velocities HGL vs. EGL Boulder D 50 (Energy Dissipation) Manning s n (WWE consulted with James Guo, Ph.D., P.E., University of Colorado at Denver) 22 11

12 FEMA Zone A and Zone AE CLOMR consideration Local Floodplain 404 Dewatering Construction Stormwater 23 MAINTENANCE Limited space Access Equipment Wall height PUBLIC SAFETY Signage Safety ladders MINERAL SPRINGS Provide recharge Open cell ACBs 24 12

13 Before After Major damage to structures and deposition of debris Two houses removed as part of basin construction 25 View south of Phase 1 debris basin, from Hwy 24 overpass (prior to Phase 2 being completed) 26 13

14 Upper debris net Middle debris net Sedimentation basin debris net 27 Before After Culvert subject to plugging and overflow Culvert removed and channel expanded 28 14

15 Debris net (middle of 3 nets) Passing area in roadway Channel and roadway - viewed from Hwy 24 overpass 29 Before After Channel improvements and removal of two houses 30 15

16 Before After 31 Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions 32 16

17 Contractor Practice - Contractor conducted drills to evacuate channel - Utilized USGS real-time gages and cameras in watershed Rock debris deposited in channel during storm on 7/16/

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19 Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions 37 Debris being removed from upper debris net following storm in August

20 Debris in middle net following May 2015 storm events 39 Debris in sediment in basin following storm in August 2015 Flow through emergency spillway in debris basin 40 20

21 41 August 2013 Post-Storm August 2015 Post-Storm 42 21

22 Background Information Design Challenges and Solutions Construction Challenges and Solutions Completed Project in Use Questions