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I 1 I I I I I I I I I I I I I I

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I 1 I I I I I I I I I I I I I I

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I           CROMLET SITE: INVERGORDON

            HANDOVER REPORT. FEBRUARY 1992


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                 Building Design Partnership
•                5 Blythswood Square
                 Glasgow
_                G2 4AD




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I   S7001



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I                                                                        Page No


I   SECTION 1    Introduction

I   SECTION 2    Land Renewal - Phase 1
                 Demolition & Decontamination Works


I   SECTION 3    Land Renewal - Phase 2
                 Reprofiling Works                                         4



I   SECTION 4    List of Available Record Drawings                          7




I   APPENDICES

    APPENDIX A   Plan showing varying thickness of capping layers

I   APPENDIX B   Plan showing locations of capped pipelines remaining on site


I   APPENDIX C

    APPENDIX D
                 Plans showing sample locations

                 Plan highlighting as built drainage system


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I   S7001


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I   SECTION 1: INTRODUCTION

    1.1   The Ministry of Defence (MoD) has retained a strategic position in Invergordon
          and the Cromarty Firth since the First World War. The MoD installations at

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          Invergordon included Cromlet Oil Storage tank farm.

          The MoD vacated their storage facility at the Cromlet site in 1982.

I   1.3   On behalf of the Property Services Agency and the Scottish Development Agency,
          Building Design Partnership carried out a land renewal study, of the Cromlet site,


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          in two stages between 1987 and 1989.

    1.4   This study comprised the following main elements:


I                 a contamination survey carried out by Strathclyde Regional
                  Chemist's Department.
                                                                                          Council




I                 a detailed site investigation yielding information on soil types, depths and
                  engineering qualities in relation to forming a structural fill site suitable for
                  housing construction.


I                 demand and development requirements of the proposed housing sectors
                  within the Invergordon area.


I   1.5   The result of the staged study was to prompt the Scottish Development Agency to
          proceed with the phased Land Renewal of the Cromlet site.



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    1.6   In April 1991 with the dissolution of the Scottish Development Agency, the
          ownership of the Cromlet site transferred to the Highlands & Islands Enterprise.
          The Highland and Islands Enterprise have continued the phased renewal of the
          Cromlet site.

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1         SECTION 2: LAND RENEWAL PHASE 1

          2.1     In September 1990, the Scottish Development Agency awarded the demolition and


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                  decontamination contract for the Cromlet site to J R Masterton & Son
                  (Demolitions) Ltd.

          2.2     General Works

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                  The contract was completed in 24 weeks, with the following works having been
                  carried out:

1                         demolition and removal of 13 oil storage tanks
                          demolition and removal of all buildings on site
•                         removal of blast protection walls to tanks
                          removal of R.C. staircases and handrails
                          removal of metal lamp standards
                          removal of all steel pipework above ground

1         2.3

          2.3.1
                  Decontamination Works

                  The contamination survey, carried out for the Stage 1 Land Renewal Study,
                  highlighted areas of the site which were contaminated due to oil, zinc, lead and less
                  notably copper.

          2.3.2   The survey concluded that:

                          the zinc and copper contamination were linked locationally with the lead
                          contamination resulting from the tank painting operations.

                          a surface scrape of the highlighted areas, whilst testing for heavy oils and
                          lead only, would result in the removal of the majority of all contaminants.

1         2.3.3   Acceptable levels of contamination, in accordance with ICRCL Guidelines, for this
                  site, known as backgarden levels, are:

1                 Lead            -              SOOppm



1 /
                  Hydrocarbons -                 0.5% of material extractable by cyclohexane

      ' 2.3.4     Removal of the contaminated material was accomplished by carrying out a 300mm            1I
                  scrape of material. The residual surface was sampled to ensure decontamination          / /
                  had been completed.                                                                     1I
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          2.3.5   Areas whose residual surface samples showed unacceptable levels of contamination
                  were given another 300mm scrape and resampled.

          2.3.6   Whilst decontamination of the basin floors was completed, sampling was also f
                  carried out on the granular material surrounding the existing field drainage system, I
                  and on the granular material forming the tank bases on 7 of the 13 bases, in order I
                  that any further contamination could be assessed.

          2.3.7   The tank base samples showed no contamination either from lead of hydrocarbons
                  whilst the field drain samples in two cases showed unacceptable levels of
                  cyclohexane and in five cases exceeded the acceptable level set for lead.

          2.3.8   No conclusion needed to be drawn at the time of this sampling as both the tank
                  bases and the field drains were to be removed during the second phase of land
                  renewal. Further sampling was to be undertaken during these operations.

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1     SECTION 3: LAND RENEWAL PHASE 2

       3.1     In June 1991, the Highland & Islands Enterprise awarded the contract for the


1      3.2
               reprofiling of the Cromlet site, to Tractor Shovels Tawse Limited.

               The Contract was carried out in 16 weeks and comprised the following main items
               of work:

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                       reprofiling the site by cut and fill method using the bund material
                       removal of underground pipelines and associated sumps
                       removal of any localised oil contaminated areas
                       removal of existing drainage system
                       installation of a land drainage system
                       grass seeding

1      3.3

       3.3.1
               Reprofiling Works

               The material found on site, as previously identified in the site investigation which
               formed part of the stage 2 land renewal study, fell mainly in two categories:

               Material 1:   The predominant material in the bunds consisted of sand containing
                             varying amounts of gravel, cobbles and boulders and locally some
                             clay and silt.

               Material 2:    This material consisted of a firm, although occasionally soft to firm,
                              clayey sandy silt or locally sandy silty clay both containing gravel
                              and occasional cobbles and boulders.

       3.3.2   Both materials proved suitable for the quality filling/reprofiling operation. Layers
               of material were specified to be laid and compacted to within 95% of their
               respective maximum dry densities.

1    I 3.3.3   Material 1 known throughout as the granular material consistently achieved
               densities higher than the specified minimum of 1875 Kg/m3.

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       3.3.4   Material 2 known throughout as the clay material also consistently
               densities higher than the specified minimum of 1975 Kg/m3.
                                                                                             achieved


1      3.3.5   Achieving insitu densities of more than 95% of the respective maximum dry
               densities should ensure settlements of minimum magnitude which should allow
•              normal foundation construction for future housing development.

1      3.3.6   The site has been covered with a capping layer (up to a maximum depth of
               350mm) which includes a 150mm deep layer of topsoil. The capping layer is
               relatively uncompacted. A plan is enclosed in Appendix A delineating the areas of
               varying thickness of capping layer.



1      3.4     Removal of Underground Pipelines

               Simultaneously with the reprofiling works, all underground pipework and associated
               sumps were removed.

1              A plan is enclosed in Appendix B showing locations and depths of pipe ends which
               have been capped as they leave the site.

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I   3.5

    3.5.1
             Removal of Localised Oil Contamination

             Following on from the sampling work carried out during Phase I of the land
             renewal, a sampling regime was established for Phase 2 to ensure that

I   3.5.2
             decontamination of the site had been achieved.

             Sampling was carried out on the residual surface upon excavation of the field

I   3.5.3
             drains, on the excavation arisings, and on the 6 tank bases which had not been
             sampled during the Phase 1 land renewal.

             A visual inspection of the trench bottoms, upon removal of the underground

I            pipework and sumps, was carried out and any visibly contaminated material was
             removed with samples being taken from the residual surface.


I   3.5.4.   Discussion of Sample Results

             Field Drain Samples

I            Cyclohexane   -       Of the 52 number samples taken, 2 samples highlighted
                                   areas where the cyclohexane level was higher than the
                                   acceptable level of 0.5%. In these two areas an additional

I                                  300mm deep scrape of material was carried out and the
                                   areas were resampled. On resampling all results were less
                                   than the permissible backgarden limit i.e. <0.5%.

I            Lead          -       Of the 52 number samples taken, only 1 sample highlighted
                                   an area where the lead level exceeded the permissible limit


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                                   of 500 ppm. An additional 300mm deep scrape was carried
                                   out in this area with the area then being resampled. On
                                   resampling the results were less than the acceptable back
                                   garden limit for lead i.e. <500ppm.

I            Tank Base. Sump and Pipeline Samples



I            Cyclohexane   -       Of the 36 number samples taken 4 samples highlighted areas
                                   where the cyclohexane level exceeded 0.5%. In these four
                                   areas an additional 300mm deep scrape of material was
                                   carried out and the areas were resampled. On resampling all

I            Lead          -
                                   results remained below the permissible limit of 0.5%.

                                   Of the 36 number samples taken none exceeded the

I                                  acceptable lead level of 500 ppm, and accordingly no
                                   further sampling was required.



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             A plan showing the location and analysis results of final samples can be found in
             Appendix C.



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1   3.7   Installation of new land drainage

          New land drainage has been installed, as shown in Appendix D, consisting of
          100mm dia. perforated tail pipes leading into 160mm dia. carrier pipes via silt traps
          and manholes, all leading to a new 1.8mm dia. manhole discharging to the existing
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          225mm diameter outfall pipe.

          The drainage system has been installed as a temporary measure to drain away
•         surface water run-off and maintain the site in a dry condition prior to the site
          being sold and developed further.

    3.8   Grass-seeding
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          The final operation during the phase 2 land renewal was to have been grass-seeding
          the 22 acre site. However this operation was postponed until spring 1992 and in
1         the interim the site has been sold for further development. The plans for seeding
          in spring 1992 have now been abandoned.

    3.9   Additional Works
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          A variation order was issued to the Contractor for the demolition and removal of
          52 pre-cast concrete lock-ups on the north boundary of the site. This work was
1         carried out by a nominated sub-contractor, Richard Fraser (Demolitions).


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I    SECTION 4: LIST OF AVAILABLE RECORD DRAWINGS



•    Record Drawings

     S7001 (11-) CO1 Existing Ground Levels

•    S7001 (11-) CO2 Plan of proposed finished ground profiles overlaid on existing ground

     S7001 (11-) CO3 Drainage layout

I    S7001 (11-) CO4 Section indicating existing & proposed ground profiles

•    S7001 (11-) COS Layout of proposed finished ground levels

     S7001 (11-) CO6 Plan of below ground pipelines

I    S7001 (11-) CO7 'OUT' survey/as built drawing

     S7001 (11-) COS Final sampling results -    Total Cyclohexane
•                                                Total Lead

     References

•    -        Environmental Safety Group AERE Harwell

              Report G-3339 "An appraisal of the Decontamination being carried out at MoD Oil
I             Storage Depot, Old Kilpatrick".

              Interdepartmental committee on the Redevelopment of contaminated land (ICRCL)
•j            Reports. ICRCL 47/81 ICRCL 58/83.

              Stage 1 Land Renewal Study


I             Stage 2 Land Renewal Study

              Cromlet Tank Farm, Handover Report, March 1991.

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I
APPENDIX A




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