Cutting the Canal
The construction of the Wilts and Berks Canal was a massive engineering undertaking that required the excavation and movement of millions of cubic yards of earth, rock, and clay between roughly 1795 and 1810. The process was categorized into several distinct types of "cutting" and excavation tasks managed by various contractors across the main line and its branches to Chippenham, Calne, and Wantage.
1. Categorisation of Excavation
The canal company differentiated between types of digging based on depth and the difficulty of the material:
- Common and Deep Cutting: Excavation was generally split into "common cutting" (typically not exceeding 4 feet 6 inches in depth) and "deep cutting" (exceeding 4 feet 6 inches, sometimes reaching depths of 17 feet or more).
- Rock Excavation: Specialized digging was required for rock-heavy sections, most notably near Shrivenham, where contractors like George Roe used gunpowder for blasting. John Clark also performed extensive rock cutting for the tunnel and deep sections near Calne.
- Pits and Courses: Massive volumes were excavated for infrastructure foundations, including lock pits, aqueduct bridge pits, and culvert pits. Workers also dug new river and brook courses to redirect natural water flow around the canal structures.
2. Waterproofing and Site Preparation
To ensure the structural integrity and water-tightness of the canal, several secondary cutting tasks were performed:
- Puddle Gutters: Contractors dug thousands of cubic yards of "puddle gutters"—narrow trenches along the canal banks that were filled with clay (puddling) to prevent leaks.
- Soil Stripping: Before the main channel was cut or spoil banks were formed, laborers performed "soil stripping" (taking off surface soil) to ensure a stable foundation for the embankments.
- Benching: This involved cutting stepped foundations into slopes to support the weight of the canal banks and prevent them from sliding.
3. Material Procurement and Maintenance
Cutting the canal was also a source of raw materials for construction:
- Brick Clay: Significant excavation was dedicated to digging clay for on-site brickmaking yards at locations like Foxham, Stanley, Pewsham Forest, and Longcot.
- Stone Quarrying: Many contractors held additional bills for quarrying stone from the canal line or nearby fields (such as Swindon Quarry) to use for road making, wharf walls, and bridge coping.
- Managing Slips: Excavation was an ongoing maintenance requirement; workers were constantly paid to clear "slips" (landslides) where the ground had given way, particularly in unstable areas like Hazeland Wood and Pewsham Forest.
4. Major Contributors to Excavation
The scale of the "cutting" is best illustrated by the volumes managed by the primary contractors:
- George Roe: Managed the largest volume, cutting over 750,000 cubic yards over 18.72 miles between Longcot and Abingdon, including the Wantage Branch.
- John Clark & Thomas Thatcher: Responsible for approximately 335,000 cubic yards over 5.88 miles on the main line and the Branch to Calne.
- Gregor McGregor: Excavated approximately 283,000 cubic yards over 6.65 miles through the Swindon and Stratton sections.
- Edwards & Camm: Handled approximately 182,000 cubic yards over 8.98 miles, focusing on the difficult embankments and valleys near Wootton Bassett and Tockenham.
- Thomas King: Excavated approximately 155,000 cubic yards over 2.64 miles, primarily between Chaddington and Longcot.
- Stephen Holland & John Bosville: Cut over 145,000 cubic yards iver 3.86 miles on the initial sections between Division of 22 & 23 (Outmarsh) to Queenfield.