Proposed electricity generation developments: peat landslide hazard best practice guide

Appendix D: Reporting

Reporting

The multi-disciplinary team responsible for reporting the PLHRA should prepare a report as part of the Environmental Impact Assessment ( EIA). This should include a factual report of the investigations undertaken as an appendix. Recommendations as to the contents of these reports follow.

Factual report structure

The following is a suggested structure for the factual report, detailing the minimum content:

(i) Introduction: a brief statement indicating who the work has been carried out for, a summary of the site location and extent, and a brief summary of the scope and purpose of the investigation;

(ii) Design of Ground Investigation: an explanation of the size and scale of the investigation, a rationale of why the locations and methods have been selected and a statement on the measures undertaken to mitigate and/or reduce potential site risks;

(iii) Field investigation and testing: a summary of the field work undertaken including, detailed mapping, detailed site investigation plans, and length of time taken to carry out the field investigation. A summary of the logging procedure and a summary of the different peat types identified onsite. Details of the samples taken and the procedures used should be included and the location and reasons for any installations should be included;

(iv) Laboratory testing: a summary of the laboratory testing that has been undertaken including summary tables of physical, chemical and geotechnical properties of each peat layer identified onsite. The information displayed should be sufficient to populate any slope stability model used in stability analysis;

(v) Appendices: A detailed series of appendices should be included to present all of the supporting information for the above sections. At a minimum this should include:

• A desk study summary plan for the site summarising all supporting mapping and observations;
• Details on the sites investigation locations including logging sheets, elevations, photos of excavation;
• A list of all samples taken including sample reference numbers, dates taken and the tests undertaken on each sample, and
• All supporting laboratory results that have been used to characterise the specific site materials and their geotechnical properties.

EIA reports

The following is a suggested structure for the EIA report, detailing the minimum content:

(i) Introduction: a statement indicating for whom the work was done, the nature and scope of the investigation, and a summary of the site location and extent;

(ii) Initial Assessment: a detailed description of the site based on the observations made by the Competent Person during their site review and site reconnaissance. It should be referenced to plans and maps of the site showing national grid co-ordinates and to a scale no smaller than 1:2,500 (this can be submitted digitally to avoid printing or presentation restrictions);

(iii) Ground Conditions: descriptions of the ground conditions found during the investigation and an interpretation of their relevance to the stability of the site and surrounding area should be provided, informed by the factual report. Anomalies in any of the data collected should be noted and their impact on confidence in interpretation clearly stated. The following items should be discussed where appropriate: geological conditions; local climate and hydrology/hydrogeology; history of past landslide events and ground movement rates; soil and peat properties, land-use history and natural environmental change. They should be supported by interpretative geological cross sections of the peat environment;

(iv) Hazard and risk assessment: the stability of the site and relevant adjacent areas should be evaluated with respect to the proposed development components (structures, communications) and any associated stabilisation measures. It is expected that particular attention be paid to the gradients of cut slopes and fills, drainage measures, retaining structures, failure mechanisms and the design criteria applied; The risks post construction and during restoration should also be presented;

(v) Discussion regarding mitigation measures: A detailed discussion should be presented of the main conclusions of the investigation and of the resulting mitigation measures that are recommended for each infrastructure component. This should include details of the recommendations to ensure both the long term peat stability of the site (taking account of the anticipated life of the development) and the short term peat stability of the site during construction. Peat landslide hazard zonation plans should be included and peat landslide hazard management plans referred to with appropriate mitigation measures, this should be achieved by the use of a risk register. It is expected that particular reference be made to matters such as: provision for free drainage of groundwater; minimising drainage diversions and specification of drain linings where site conditions require them; avoidance of natural drainage pathways ( e.g. gullies, soakaways) and provision of flexible jointed pipes capable of sustaining small movements without leakage;

(vi) Conclusion and Recommendations: Conclusions and recommendations should be presented stating the outcome of the above discussion.

Assessors Report

The assessment report by the Assessor will take account of the following work areas:

• Schedule of work;
• Site selection;
• Sampling equipment and strategy;
• Techniques and methodology;
• Sample analysis;
• Risk assessment/register;
• Recommendations on mitigation measures;
• Proposals for further investigation;
• Summary of requirements;
• References used.