A30 Chiverton to Carland Cross Environmental Statement Volume 6 Document Ref 6.4 ES Appendix 9.1 WSP Preliminary Sources Study Report HA551502-WSP-EGT-SW-RP-LE-000001 August 2018 Planning Act 2008 Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 (as amended) APFP Regulation 5(2)(a) iii TABLE OF CONTENTS EXECUTIVE SUMMARY .............................................................................1 1 PROJECT BACKGROUND ..........................................................2 1.1 SCOPE AND OBJECTIVES OF THE REPORT ............................................... 3 1.2 OTHER RELEVANT INFORMATION .............................................................. 3 2 SOURCES OF INFORMATION ....................................................4 2.1 MAPPING ....................................................................................................... 4 2.2 GROUNDSURE REPORT ............................................................................... 5 2.3 GEOLOGICAL MAPS AND RECORDS .......................................................... 5 2.4 BOREHOLES ................................................................................................. 5 2.5 ENVIROCHECK .............................................................................................. 5 2.6 HADGMS INFORMATION .............................................................................. 5 2.7 HISTORICAL MAPPING ................................................................................. 5 2.8 UNEXPLODED ORDNANCE .......................................................................... 5 2.9 HYDROGEOLOGY ......................................................................................... 6 2.10 GEOTECHNICAL DESK STUDY AND GROUND INVESTIGATION REPORTS....................................................................................................... 6 2.11 UTILITIES SERVICES .................................................................................... 7 2.12 TOPOGRAPHY ............................................................................................... 7 2.13 ENVIRONMENT .............................................................................................. 7 2.14 MINING ........................................................................................................... 7 3 FIELD STUDIES ...........................................................................8 3.1 WALKOVER SURVEY .................................................................................... 8 3.2 SITE WALKOVER SURVEY RESULTS .......................................................... 8 3.3 PREVIOUS GROUND INVESTIGATIONS ..................................................... 30 A30 Chiverton to Carland Cross WSP | Parsons Brinckerhoff Highways England Project No 62105222-001 March 2017 iv 3.3.1 LONDON – PENZANCE TRUNK ROAD A30 PENHALE TO CARLAND CROSS IMPROVEMENT SITE INVESTIGATION REPORT, THE DEPARTMENT FOR TRANSPORT 1988 .............................................. 30 3.3.2 A30 CARLAND CROSS TO CHIVERTON CROSS PRELIMINARY GROUND INVESTIGATION FACTUAL REPORT, SOIL MECHANICS 2004 ........................................................................................ 31 3.3.3 A30 CHIVERTON CROSS ROUNDABOUT GEOTECH REPORT, PARSONS BRINCKERHOFF 2005 ............................................................... 33 3.3.4 A38 CHIVERTON ROUNDABOUT CCTV GEOTECHNICAL REPORT, ACCORD 2008 ............................................................................. 34 4 SITE DESCRIPTION ...................................................................35 4.1 GEOGRAPHY ............................................................................................... 35 4.2 TOPOGRAPHY ............................................................................................. 35 4.3 HISTORICAL DEVELOPMENT ..................................................................... 36 5 GROUND CONDITIONS .............................................................42 5.1 REGIONAL GEOLOGY................................................................................. 42 5.2 LOCAL GEOLOGY ....................................................................................... 42 5.3 DRIFT GEOLOGY......................................................................................... 42 5.4 SOLID GEOLOGY ........................................................................................ 44 5.5 HYDROLOGY ............................................................................................... 46 5.5.1 REGIONAL ..................................................................................... 46 5.5.2 LOCAL ............................................................................................ 46 5.6 LAND DESIGNATIONS ................................................................................ 50 5.7 MINING ......................................................................................................... 50 5.8 CONTAMINATION ........................................................................................ 53 5.8.1 SUMMARY...................................................................................... 53 5.8.2 GROUND CHARACTERISATION ................................................... 53 5.9 GROUND CONDITIONS ............................................................................... 54 5.9.1 EXISTING BOREHOLE DATA......................................................... 54 5.9.2 IDENTIFIED GEOLOGICAL RISKS ................................................. 57 6 PRELIMINARY ENGINEERING ASSESSMENT ........................57 6.1 OVERVIEW................................................................................................... 57 6.2 EXCAVATABILITY – MADE GROUND, ALLUVIUM AND HEAD DEPOSITS .................................................................................................... 57 A30 Chiverton to Carland Cross WSP | Parsons Brinckerhoff Highways England Project No 62105222-001 March 2017 v 6.3 EXCAVATABILITY – WEATHER AND UN-WEATHERED BEDROCK ......... 57 6.4 PILING .......................................................................................................... 57 6.5 EARTHWORKS ............................................................................................ 57 6.6 CUTTINGS.................................................................................................... 58 6.7 EMBANKMENTS .......................................................................................... 58 6.8 SUBGRADE.................................................................................................. 58 6.9 MATERIAL CLASSIFICATION AND RE-USE ............................................... 58 6.10 STRUCTURE FOUNDATIONS...................................................................... 58 6.11 IMPLICATIONS AND FEASIBILITY OF THE SCHEME ................................ 58 7 COMPARISON OF PROJECT AND RISKS ...............................59 7.1 PRELIMINARY GEOTECHNICAL RISK REGISTER ..................................... 59 7.1.1 GEOTECHNICAL RISK ASSESSMENT .......................................... 59 8 REFERENCES............................................................................68 A30 Chiverton to Carland Cross WSP | Parsons Brinckerhoff Highways England Project No 62105222-001 March 2017 vi TABLES TABLE 4-1 : SUMMARISED TOPOGRAPHY ................................................................ 35 TABLE 4-2: SUMMARISED HISTORICAL DEVELOPMENT .......................................... 37 TABLE 5-1: WEATHER AVERAGES FROM CAMBORNE WEATHER STATION .......... 46 TABLE 5-2: SUMMARY OF HYDROGEOLOGY DATA.................................................. 47 TABLE 5-3: ESTIMATED LEVELS OF CONTAMINATION ............................................ 53 TABLE 5-4: EXISTING BOREHOLES SUMMARY ......................................................... 54 TABLE 7-1: IMPACT INDEX.......................................................................................... 59 TABLE 7-2: LIKELIHOOD INDEX .................................................................................. 59 TABLE 7-3: RISK MATRIX ............................................................................................ 60 TABLE 7-4: GEOTECHNICAL RISK REGISTER ........................................................... 61 ANNEX A-1: DETAILS OF PROPOSED EXPLORATORY HOLES ..................................2 A30 Chiverton to Carland Cross WSP | Parsons Brinckerhoff Highways England Project No 62105222-001 March 2017 vii FIGURES FIGURE 1.1: SECTION OF A30 PROPOSED FOR IMPROVEMENT ..............................2 FIGURE 2.1: ORDNANCE SURVEY MAPPING OF THE STUDY AREA AT SCALES: (A) 1:200K AND (B) 1:100K..................................................................4 FIGURE 2.2: UXO RISK MAP .........................................................................................6 FIGURE 4.1: WALKOVER PHOTOGRAPH SET A ..........................................................8 FIGURE 4.2: WALKOVER PHOTOGRAPH SET A ..........................................................9 FIGURE 4.3: WALKOVER PHOTOGRAPH SET B ..........................................................9 FIGURE 4.4: WALKOVER PHOTOGRAPH SET B ........................................................ 10 FIGURE 4.5: POSSIBLE ACCESS LOCATION FOR CHAINAGE 2000M – 2300M. ....... 10 FIGURE 4.6: WALKOVER PHOTOGRAPH SET C ........................................................ 11 FIGURE 4.7: WALKOVER PHOTOGRAPH