Del Mar Bluff Stabilization Update to Del Mar City Council, March 5 - - PowerPoint PPT Presentation

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Del Mar Bluff Stabilization Update to Del Mar City Council, March 5 - - PowerPoint PPT Presentation

Feb 02, 2023 389 likes •1.01k views

Del Mar Bluffs Stabilization Project Update Del Mar Bluff Stabilization Update to Del Mar City Council, March 5 th 2018 by Bruce Smith of SANDAG and Patricia McColl of HNTB Coast Boulevard to Del Mar Bluffs Project Area Torrey Pines Overhead

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Del Mar Bluffs Stabilization Project Update

Del Mar Bluff Stabilization

Update to Del Mar City Council, March 5th 2018 by Bruce Smith of SANDAG and Patricia McColl of HNTB

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Torrey Pines Overhead Bridge Coast Boulevard to

Del Mar Bluffs Project Area

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  • 1998 Drainage Outfall & Soil Cement Stabilization at 11th Street (NCTD)
  • 2000 DMB Geotech Study (NCTD)
  • 2001 Emergency Repairs at 8th Street (NCTD)
  • 2001 Drainage Study
  • 2003 Drainage Improvements & Landslide Warning System (NCTD)
  • 2007 Del Mar Bluffs 2 stabilization with Soldier Piles (SANDAG)
  • 2009 Del Mar Bluffs 3 stabilization with Soldier Piles (SANDAG)

Future Planning

  • 2017 Del Mar Bluffs 4 (PSR prepared for Urgent Repairs)
  • 2020-2030 DMB 5….. (Improvements for 50 year Design Life)

Del Mar Bluffs Projects

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Soil Cement Buttress 11th Street in 1998

New Drainage Outfall

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Del Mar Bluffs Geotechnical Study

  • NCTD Prioritized areas in need
  • f stabilization
  • Presented full range of

stabilization alternatives

  • Del Mar City Council Review -

May 2001

  • Approved by NCTD Board in

July 2001 after incorporating City Review comments

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  • 1. Maintain and Improve drainage
  • Repair culverts and drainage swales
  • Add sub-drains and hydro-augers
  • 2. Landslide warning system until funds available for stabilization
  • 3. Bluff stabilization with;
  • Soldier Piles
  • Soil cement buttress
  • Soil nails
  • Sea walls

Stabilization Alternatives Considered

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Priorities from Slope Stability Analysis

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Sub Drainage Improvements

Interceptor Trench Drain

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Subsurface Drainage Improvements

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Soldier Pile Alternative

  • Viable for all stabilization areas

Tieback Anchor (Optional) L Existing Track C Original Ground Grade Beam Vertical Pile

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Soil Cement Buttress Alternative

  • Viable for most stabilization areas

Original Ground L Existing Track C Excavation Stepped Soil Cement Buttress Facing Shotcrete (Optional Seawall)

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Soil Nail Alternative

  • Viable for SA-7, SA-9 and SA-6B

Original Ground L Existing Track C Facing (Optional) Shotcrete Soil Nail Typ

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Seawall / Retaining Wall Alternative

  • Viable for SA-1, SA-3 and SA-10 (East)

L Existing Track C Seawall Concrete Reinforced Ground Original Back Cut

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Alternative Evaluation

Stabilization Alternative Evaluation Criteria Rank Overall

Constructability Cost Environmental Considerations Soldier Pile Best Best Best Best Soil Cement Buttress Worst Mid-Level Worst Worst Soil Nail Reinforcement Mid-Level Best Mid-Level Mid-Level Seawall Worst Mid-Level Worst Worst Retaining Wall Mid-Level Mid-Level Best Mid-Level

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2001 Wall Slid Down Bluff at 8th St.

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2001 Emergency Project

Piling installation

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2001 Emergency Project

Sculpted Pile Cap

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Del Mar Bluffs Stabilization Project 1 – 2003

Drainage Improvements and Landslide Warning System

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DMB1 Drainage Improvements

Many drainage improvements included:

  • Installed and repaired new drainage structures
  • Relined concrete ditches
  • River stone energy dissipators
  • Storm water filtering system at street ends
  • Hydro-augers at several locations on bluff face
  • Interceptor Trench Sub Drains east of tracks
  • Supported large drainage chute at 12th Street
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DMB1 Drainage Improvements

Replaced headwall Installed new pipe and outlet on beach improved drainage capacity MP 244.7 – Near 8th Street.

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DMB1 Construction of Sub-drains at 7th Street

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Del Mar Bluffs

Surface and Sub-Surface Runoff

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DMB1 Drainage Improvements at 4th Street

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DMB1 Drainage Improvements

Grouted underneath and hand repaired Drainage flume at 12th St.

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DMB1 Hydroauger Installation

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DMB1 Hydroauger Installation

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DMB1 Slope Monitoring and Landslide Warning System

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Del Mar Bluffs 2 and 3 Stabilization Track side piles

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Soldier Pile and Tieback

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Drilling Soldier Pile Drilling

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Placing Concrete from Low Railer

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Del Mar Bluffs Existing and Future Stabilization with piles west of track

* *

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Del Mar Bluffs Proposed Future Stabilization

All areas will be environmentally cleared * Indicates proposed with DMB 4 but not yet funded

Area Designation Station Importance Ranking (IR) DMB3 Length (Feet) SA-9* 1479+82 4 160 SA-8* 1482+25 5 135 SA-5 1512+15 6 90 SA-3 1517+06 6 198 SA-6N 1493+77 7 200 Total Proposed 783

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  • Repair Drainage

Structures

  • Install piling to

increase factors of safety

  • Stabilize structures

threatened by erosion and corrosion

Del Mar Bluffs 4 Urgent Repairs

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Stabilize Storm Drain Headwall MP 244.3

Rockscaped headwall with soil nail tiebacks

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Piling at Timber Retaining Walls

CIDH pile supports for 70-foot long section below 7th Street

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Piling at Timber Retaining Walls

CIDH pile supports for 200-foot long section below 13th Street

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Storm Chute MP 244.4 Below 12th St.

Stabilize end of outfall with concrete

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New Drainage Channel 6th Street to 8th Street

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Slope Failure at 7th Street

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Slope Stabilization at 7th Street

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Original Ground Line Slurry Backfill Match Bluff Color Failed Slope

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Replace Drainage Channel at 8th Street

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Grade Path Upper Bluff 6th to 8th Street

Add Stabilized Decomposed Granite Surfacing

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Slope Stabilization at Anderson Canyon

CIDH piles and lagging wall

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Repair drain and wall North of 10th Street

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Support drain with wall at 10th Street

CIDH piles and lagging wall to support drainage channel

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10th Street Wall Repair

CIDH piles and lagging wall to support drainage channel

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9th Street – Repair erosion at flood wall

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Remove Hydro-auger Debris

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Beach Access

  • Life Guard Tower (17th Street)
  • State Park

Right of Way

  • Coast Boulevard
  • State Park
  • 12th Street
  • Penny Lane
  • 10th Street

DMB4 Construction Staging and Access

  • 9th Street
  • 8th Street
  • 7th Street
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Access 17th Street to 12th Street

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Access 11th Street to 7th Street

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Access from State Park

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Access from State Park

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Questions and Contacts

SANDAG

Bruce Smith Corridor Director bsm@sandag.org Allie DeVaux Project Manager adev@sandag.org

Design Project Team

Tricia McColl HNTB Project Manager pmccoll@hntb.com Sean Colorado Leighton Geotech scolorado@leightongroup.com David Olson Leighton Geotech dolson@leightongroup.com

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Assuming continued bluff retreat from erosion additional stabilization measures will be needed including:

  • Replacement and repair of aging structures
  • Bluff stabilization based on erosion events by either;
  • Stabilize local erosion areas
  • Additional piles and tie backs
  • Lagging between piles
  • Bluff toe protection
  • A combination of the above

DMB 50 Year Stabilization Estimate ($36m - $82m)

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Bluff Retreat Rates

A retreat rate of 6 inches per year assumed for DMB 2 and 3

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Atmospheric River

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Sorrento Valley Station – December 2010 5 inches rainfall in 3 days

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Del Mar Bluffs Stabilization Project Update

Del Mar Bluffs History of Rail Service