Lyme Regis No longer Slipsliding Away September 1

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 regraded 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 shingle § Raised beach level by 2 meters

Beacon Rocks

} Armor rocks: § § § 11, 000 tonnes core rock, 2 - 5 tonnes each 26, 500 tonnes armor, 9 - 18 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