Lyme Regis No longer Slip-sliding Away September 1, 2006

Introduction

Location  England  Southwest Coast  Dorset  Jurassic Coast World Heritage Site  Exposed to severe winter storms

West, 2006

Stormy Weather Undated, 1970’s storm Source: West, 2006

Calm Weather

The Geology of Lyme Regis  Greensand  Clay  Shale  Blue Lias

Steep slope

The Beginnings of a Landslip  Charmouth Road Car Park  Asphalt is contributing to landslip  Work underway to improve drainage system

The Black Venn  Between Lyme Regis and Charmouth  Mostly Clay and Shales with Beef  Prone to landslides  Rich source of fossils

The Blue Lias  West of Lyme Regis at Monmouth Bay  Greensand  Clay  Limestone

Landslides  1962 Langmoor Gardens  Caused by construction activities  The area was re- graded and Langmoor gardens were established

The Spittles  East of Lyme Regis  The whole system was reactivated in 1986

Long-shore drift interrupted  Beach buildup  Monmouth beach  Increased protection  Beach depletion  Shingle supply interrupted  This results in depletion

The depleted beach(1960’s) and breached seawall (1974)

Coastal Defenses - The Cobb

Coastal Reinforcements  Beacon Rocks extended by 110 meters  North wall rockery realigned  Added rock armor at Cobb Gate  New jetties at Lister Gardens and Cobb Gate  Beach replenishments  Sand and shingle  Raised beach level by 2 meters

Beacon Rocks

 Armor rocks:  11,000 tonnes core rock, tonnes each  26,500 tonnes armor, tonnes each  Source: Norwegian granite  Byproduct of granite counter top industry  Shingle (pebbles):  72,000 tonnes  Source: Isle of Wight  Sand:  37,000 tonnes  Source: northern France  Precast concrete:  Source: UK  Limestone facing  Source: China

Rock Armor at Cobb Gate Jetty

Finishing up at Cobb Gate Jetty

Reinforcements at Cobb Gate

Lyme Harbor beach restored

Work continues at Langmoor Gardens

Slope stabilization  Began in 2005, scheduled completion 2007  Major engineering effort involved considerations for seismic stability  Only small equipment allowed until slope was sufficiently stabilized  Gradual increase in machinery size based on monitoring

 1,150 auger-cast piling  Drilled holes thru clay into bedrock  Filled with concrete and reinforcement  Act as dowels to hold slope  Soil nails  Similar to piling but horizontal  2,300 meters drainage  Counterforts - at base  Drilled drains -in hill  French drains - below car park

Conclusion  Phase II construction is nearly complete  Coastal defenses  Slope stabilization  Increased security for town  Increased income due to tourism  Cost to maintain will be less than the cost of emergency repairs