tullabeg 110kv substation ground investigation report€¦ · document “specification for road...

Malachy Walsh and Partners Engineering & Environmental Consultants

Cork | Tralee | Limerick | London

Tullabeg 110kV Substation

Ground Investigation Report

Client: H&MV Engineering Ltd, Unit B10, Kingswood Business Park, Clondalkin, Dublin 22 D22 C7XO

Project No: Revision: Prepared

By:

Approved

By:

Date:

20609-6003 E P. Curran J. O’Leary October

2019

Tullabeg Substation 20609-6003-E Ground Investigation Report October 2019

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TABLE OF CONTENTS

1 INTRODUCTION .................................................................................................................................... 3

2 GEOLOGY OF SITE .............................................................................................................................. 3

3 GROUND INVESTIGATION SUMMARY ............................................................................................... 5

4 INITIAL ENGINEERING ASSESSMENT ............................................................................................... 7


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1 INTRODUCTION

The purpose of this report is to present the ground investigation information obtained at the site of the proposed Tullabeg Substation, Co Wexford. The trial pits were completed on 09.07.2019.

Figure 1-1 Site Location

2 GEOLOGY OF SITE The Geological Survey of Ireland online mapping system shows the bedrock at the site to be part of the Campile Formation which consists of Rhyolitic volcanics, grey & brown slates (See Figure 2-1). The Quaternary Sediments at the site are mapped as Irish Sea Till (“Till derived from Limestone”). Alluvium and “Bedrock at Surface” is also mapped to the north of the site (See Figure 2-2).


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Figure 2-1 Bedrock Geology

Figure 2-2 Quaternary Geology

Site Location

Irish Sea Till

Site Location

Campile Formation


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3 GROUND INVESTIGATION SUMMARY The below table summarises the findings of the ground investigation. Photographs of the trial pits are appended to this report.

Figure 3-1 Site Layout and Trial Hole Locations


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Trial Pit Number

Stratigraphy Ground water Stability

TP01

0.00-0.4 Topsoil & Subsoil

None encountered

Good

0.40-3.00 Stiff Grey/Brown Sandy Gravelly CLAY with occasional cobble and boulder. Gravel is angular from Limestone origin

TP02

0.00-0.30/0.5 Topsoil & Subsoil (depth varied slightly throughout trial pit)

None encountered

Good

0.30/0.50 - 3.30 Firm to Stiff Grey/Brown Sandy Gravelly CLAY with occasional boulder. High boulder and cobble content from approx 2m depth

TP03

0.00-0.30/0.4 Topsoil & Subsoil

None encountered Good

0.30/0.40 - 3.30 Stiff to Very Stiff, Grey/Brown Sandy Gravelly CLAY with occasional cobble and boulder. Clay land drain noted at 0.3m depth.

TP04

0.00-0.30/0.4 Topsoil & Subsoil


0.30/0.40 - 3.00 Stiff Grey/Brown Very Sandy, Very Gravelly CLAY with occasional cobble and boulder. Crumbles on rolling on hand. Pockets of very stiff black clay noted with soil mass.

TP05

0.00-0.30 Topsoil and Subsoil


0.30-1.10 Firm to Stiff Grey/Brown Sandy Gravelly CLAY


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4 INITIAL ENGINEERING ASSESSMENT The Glacial Till (Stiff Sandy Gravelly CLAY) encountered at approximately 0.3 to 0.5m ground level is likely to provide a suitable formation layer for the structures on this site. Plate load testing will be required at construction stage to prove the design bearing capacity is achieved. Permanent cuttings in Glacial Till at this site should be at an angle of 1V:2H or shallower. The reusability of material excavated from the substation site has been assessed based on TII document “Specification for Road Works Series 600 – Earthworks (CC-SPW-00600 March 2013)”. The Glacial Till excavated at this site is likely to classify as a Class 2 A/B/C (General Fill) or Class 4 (Fill to Landscape Areas). The Glacial Till is not likely to meet the requirements for Class 6F or 6N. Class 6F and 6N typically require the use of crushed rock to meet the specification. Import of quarried material from an external quarry will be required for construction of the substation compound. The material should be sourced from a quarry that is certified to provide Class 6F and 6N material that meets the requirements of SR21. A localised dip was noted on the western boundary of the substation compound which is likely to required additional fill to bring it to the same level as the rest of the site. A surface land drain was noted at the southern boundary of the site. The fall in the drain appeared to be from west to east. Clay pipe land drains were encountered at approximately 300 to 500mm below ground level in two of the trail holes. Further clay drains are likely to be encountered onsite.

Appendix A

Trial Pit Photographs


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TP01 – Photo 1


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TP01 – Photo 2


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TP01 – Photo 3


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TP01 – Photo 4


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TP01 – Photo 5


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TP02 – Photo 1


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TP02 – Photo 2


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TP02 – Photo 3


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TP02 – Photo 4


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TP02 – Photo 5


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TP03 – Photo 1


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TP03 – Photo 2


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TP03 – Photo 3


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TP03 – Photo 4


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TP03 – Photo 4


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TP04 – Photo 1


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TP04 – Photo 2


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TP04 – Photo 3


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TP04 – Photo 4


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TP04 – Photo 5


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TP04 – Photo 6


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TP05 – Photo 1


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TP05 – Photo 2


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TP05 – Photo 3


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TP05 – Photo 4

tullabeg 110kv substation ground investigation report€¦ · document “specification for road...

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