HolmesCo: Site Investigation
Week 5 handout — Experimental design
This is a fictional document for teaching purposes. Any resemblance to real consultancy reports is deliberate and cautionary.
HolmesCo
Geological Consultants Since 2019
“Building Confidence in the Ground Beneath You”™
GROUND INVESTIGATION REPORT
Prepared for: DNS Developments Ltd
Project: Proposed Esh Spinning Wind Farm, County Durham
Report No.: HC-2026-0347
Date: February 2026
Classification: CONFIDENTIAL
1. Introduction
HolmesCo was appointed by DNS Developments Ltd to undertake a ground investigation at the proposed Esh Spinning Wind Farm, a twelve-turbine development near Esh, County Durham (NGR NZ 190 440). The turbines are proposed along the ridge between Quebec, Esh and Hill Top, at 190–235 m AOD.
The purpose of the investigation was to determine whether the bedrock is suitable to support wind turbine foundations.
2. Methodology
Three boreholes were drilled to a depth of 15 metres each:
| Borehole | Location | Elevation (m AOD) |
|---|---|---|
| BH-01 | Verge of access road, Deerness valley floor | 104 |
| BH-02 | Verge of access road, 200 m east of BH-01 | 108 |
| BH-03 | Lay-by on access road, lower valley side | 116 |
Drilling was carried out by HolmesCo’s in-house rotary rig between 8–10 January 2026. Continuous core was recovered from all three boreholes. Standard penetration tests (SPTs) were conducted at 1.5 m intervals.
Borehole locations were selected alongside existing access roads to ensure safe and efficient access for the drill rig, which requires a level, firm platform and proximity to a road for support vehicles.
3. Results
All three boreholes encountered the following sequence:
- 0–2 m: Glacial till (firm to stiff clay with gravel)
- 2–15 m: Sandstone (Pennine Lower Coal Measures Formation), moderately strong to strong, thinly to medium bedded, occasional thin mudstone and siltstone interbeds
SPT N-values in the sandstone ranged from 35 to 50+ (refusal), indicating competent rock.
No groundwater was encountered during drilling. No significant discontinuities, voids or zones of weakness were observed in the recovered core.
4. Conclusions
Based on the results of this investigation, the bedrock at the Esh Spinning Wind Farm site comprises competent sandstone of the Pennine Lower Coal Measures throughout. The site is considered suitable for wind turbine foundations subject to detailed foundation design.
HolmesCo recommends proceeding to the detailed design phase with confidence.
This report has been prepared by HolmesCo for the exclusive use of DNS Developments Ltd and should not be relied upon by third parties. HolmesCo accepts no liability for losses arising from use of this report. Standard terms and conditions apply.