Chatterley Valley, part of the Ceramic Valley Enterprise Zone, is a new industrial and logistics development strategically located by the A500, just 4 miles from M6 Junction 16. With a live rail siding to the West Coast Mainline, the 1.2 million sq. ft site is set to create 1,700 jobs, boosting local economic activity, skills, and job density.
John F Hunt Regeneration were engaged to provide earthworks and mine stabilisation works to prepare the 45-hectare site for subsequent commercial development and associated infrastructure.
Scope of Works
- Complex earthworks: Over one million cubic metres of cut and fill operations.
- Spine road construction: Development of a key transport artery through the site.
- Drainage installation: Approximately 5km of drainage infrastructure, including batter drainage to ensure slope stability.
- Mine stabilisation: Drilling and grouting of mine workings, addressing 23 confirmed and potential shafts.
- Environmental enhancements: Measures to support biodiversity and sustainability.
PCSA Phase
We took over the contract after the previous earthworks contractor went into administration. During the Pre-Construction Services Agreement (PCSA) phase, we reviewed prior work, conducted additional site investigations and lab testing, and refined the ground condition analysis. This defined a clear scope and technical specifications, ensuring the successful completion and validation of the earthworks and mine stabilisation.
The project involved targeted delineation using various drilling, probing, and in-situ testing techniques to develop a detailed ground model. Extensive below-ground infrastructure was installed, including rod settlement gauges and vibrating wire piezometers, to monitor Ground Improvement Works (Preload Soil Panels). All installations followed in-house quality protocols, with survey records, checklists, and calibration checks completed.
Earthworks
The site preparations involved extensive recontouring across the valley side extending some 1.5km in length with elevation differences across the site of up to 30m. The creation of the five development plateaus involved approx. one million cubic metres of cut and fill, which was carefully designed and modelled to achieve a zero balance. This sustainable approach minimised unnecessary HGV movements (import shortfalls / export surplus materials).
Extensive slope drainage was installed to ensure stability of the escarpments and minimise soil erosion. The development plateaus were carefully designed and constructed to convey run-off to temporary peripheral ditches to avoid scour and ensure the durability of the new landform. Numerous catchpits / silt traps were also installed to mitigate pollution as the site transitions through the follow-on construction phase.
Earthworks methodologies were demonstrated in advance through test panel trials, materials classification (laboratory) and end product compaction (field based) testing.
Mine Stabilisation
Site preparations involved extensive investigation and remediation work to deal with the hazards and risks arising from former coal mining. Comprehensive investigations were conducted to check for shafts and the locations of other infrastructure based on Mining Remediation Authority records and assess the presence of coal seams and weak / disturbed ground.
Extensive drilling and grouting was undertaken to stabilise the ground and protect the future development from subsidence risk.
Some 1,900 holes were drilled to depths up to 150m and more than 2,850 tonnes of PFA cement grout were injected in targeted areas to stabilise impacted ground.
Historical shafts were also treated or removed. A total of 1500 tonnes of pea gravel were placed and more than 500 tonnes of PFA grout were injected to stabilise legacy shafts which extended to depths up to 140m. Reinforced concrete caps were also designed and constructed to ensure residual risks remained negligible.
Infrastructure Works
A sitewide spine road was built to serve the development plots. Its construction included the installation of approx. 1.5km of foul and storm water sewer mains. Approx. 1.8km slope drainage, and 2km of land drains and counterfort drainage were installed to ensure stability of the slopes and the newly constructed landform. Stormwater attenuation ponds were created to provide sufficient flood alleviation capacity for the scheme. The infrastructure works also included the construction of an 11kV substation, approx. 3.7km of ducting for power and a further 1.8km for street lighting. BT and water mains were also installed.
To provide improved public access and reduce risks for vulnerable road users, footpaths were reinstated and new public rights of way including a cycle path were constructed.
