Pyrite Testing and Methodology for Remediation Works Key Aspects of I.S. 398 (Parts 1 and 2) Verification and Preparation for Remedial Works

Transcription

1 Pyrite Testing and Methodology for Remediation Works Key Aspects of I.S. 398 (Parts 1 and 2) Verification and Preparation for Remedial Works Jim Mansfield November 2013

2 Verification and Preparation for Remedial Works a) Verification of presence of pyrite b) Establishment of works requirements

3 Engineering Brief PRB/Housing Agency will invite engineers to tender for groups of houses in various numbers. These will generally have a Damage condition Rating of 2, possibly 1, and will have had Building Condition Assessments prepared by the house owner s engineer. The engineer will generally be sole consultant to PRB/Housing Agency but may use sub-consultants at his discretion. Two stages a) Verify presence of pyrite b) Remediation, preparation of documents, tendering, monitoring and certification Engineer to tender to PRB/Housing Agency for these services

4 Two Stage Process a) Verification Brief from PRB/Housing Agency Group of houses with BCA s, Assume BCA s are generally 2 If 0 responsibility is owners If 1 owner generally to await results until level 2 is reached. There may be cases where a decision is made by PRB to allow remedial work for 1s if they are in groups of 2. If 2 (or 1 with decision to remediate made) - verify presence of pyrite by testing to I.S. 398 Part 1 by testing PRB responsibility Note: This is not a forensic investigation nor is information being obtained for court actions

5 Building Condition Assessments Not part of this course, previous course Includes a desk study, Non-invasive inspection internally and externally Sketches, photographs, level records, crack widths Assignment of attribute values. Determination of Damage Condition Rating 0, 1 or 2 Re-inspection if required These assessments are given to PRB. Generally if DCR2 then passed to PRB engineer for remediation

6 Figure 1 I.S. 398 Part 1 See next slides for discussion

7 Damage Condition Rating Report No Certificate Required No Action Certificate Required Take Samples (2 minimum) 2 All actions by Ow ners and/ or their Engineer No PRB action Test Suite 0 each sample PASS FAIL CAT A Negligible Risk Issue Certificate PASS XRD Test Suite 2 FAIL CAT B or C No Certificate At Risk - Amber House Owner s Engineer Refer to PRB

8 Building Condition Assessment Damage Condition Rating Recommend Re-inspection (6 months) Proceed as DCR 2 PRB/ Pyremco PRB Engineer NO Progression Confirmed YES Cert Required NO Re-inspect 12 months Progression Confirmed YES No Action YES Take 2 Samples FAIL Test Suite 1 PASS Inconclusive Category B or C Remedial Work Required Amber FAIL Test Suite 2 PASS Consider Other causes Pass to Pyremco for consideration Report by House Owners Engineer

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10 Test Suite 1 Test Suite 0 TEST SUITES Tables I.S. 398 Part 1 Parameter Pass Non Conclusive Fail Acid soluble sulphide As 0.2% S0 4 >0.2% S0 4 Water soluble sulphate As 500mg/LS mg/L < Content 500mg/L1 >1500 mg/l1 S0 4 S0 4 S0 4 Total Sulphur 0.3% S 0.3% < Content 1.0% S >1.0% S Proportion of fine grained sedimentary rock Evidence of secondary crystallisation 10% 10% < Content 30% >30% Presence of gypsum in XRD N Y N Y Test Suite 0 Test Suite 1 Inconclusive Pass All Green Fail Any Fail or Non Conclusive proceed to XRD and Test Suite 2 Pass All Green Fail All Red Any mixture other than above. Hardcore Testing Results

11 Sampling of Infill Hardcore Sampling Procedure Section 6 I.S.398 Part 1 Flowchart given in Figure 1 Engineer to determine appropriate number of tests Generally 2 for buildings with ground floor area < 60 sqm but subject to area, geometry and knowledge from other sources Check for services, power, gas water, drainage, tv etc Confirm to owner and coring company that services will not be compromised. Switch off power Use competent person for coring Sampling procedure given in code Inspection report required Repair as per code

12 Testing Location I.S Area where heave is most evident to be agreed (Consider use of house and likely remedial timescale) - However for further remedial work it would be better if beside wall as this will allow foundations be determined. - Need to determine pyrite as per Test Suites - But also depth of stone (middle of floor), type of ground floor construction (isolated, floating within the walls, over walls, suspended) - Presence of reinforcement - Thickness of floor - Presence of Radon Barrier - Insulation (thickness and type) - Presence of ground water (Other issues screeds, under floor heating and services)

13 Assume BCA damage condition rating 2 How many tests 1 sample per house minimum. Note code advises two samples per 60 sq m. But if knowledge on estate/infill source etc. has previously been determined, the number of tests could be considered by engineer in conjunction with PRB (perhaps 50% of houses minimum, for discussion) Note: possibility of 2 nd sample needed if pass achieved in first test. Again this may be based on previous experience What is correlation between DCR2 + Red (high ~ 1 sample / low medium ~ 2 sample) Experience will confirm these results A number of tests should be confirmed with PRB with provision of summary results

14 Test procedure Section 7 I.S. 398 Part 1 This lecture will not deal with details of tests as they will be done by a laboratory/ geologist determined in conjunction with the PRB 3 different test suites Section 7 Selection dependant on Damage Condition Rating and Whether a certificate is required or not. Testing by accredited laboratory etc Table 1 I.S. 398 Part 1 Test Suite 0 i) Geological inspection ii) Chemical testing Test suite 1 as Test Suite 0 but with iii) Mineralogical analysis by quantitative X-ray Diffraction(XRD) Test Suite 2 i) Thin section petrographic analysis ii) Water absorption test Test suite 2 follows test suite 0 or 1 See table 4 I.S. 398 Part 1 for 11 factors to be considered

15 Test Results Hardcore Sampling Reporting template Annex D 1.0 Information on building, sampling method, presence of ground water, photographs etc 2.0 Information on sampling company 2.1 Floor Slab - thickness, material, etc 2.2 Insulation - thickness, type, etc 2.3 Sand blinding - sample, thickness, particle size, moisture content, etc 2.4 Hardcore - thickness, colour, voids, particle shapes, rock types and lithology, moisture conditions, presence of crystal growth, etc 2.5 Water - ph, temperature etc Form may have comments and is to be signed by appropriate person.

16 Test Results Laboratory testing Reporting template Annex E 1.0 Information on building 2.0 Information on firms involved - geological inspector, petrographic assessment. Physical testing 2.1 Test Suite 0 results - geological inspection, chemical testing 2.2 Test Suite 1 results X-Ray diffraction results (XRD) 2.3 Test Suite 2 results physical testing, water absorption Classification of Hardcore Pass Not susceptible to expansion Inconclusive Susceptible to limited expansion Fail Susceptible to significant expansion Comments, signature, qualifications etc

17 Test Suite 2 (Table 4 I.S. 398 Part 1) Series of 11 factors for consideration These are based on Chemical tests and calculations, Petrographic Examination, XRD, Moisture content, Water absorption Geological Inspections Hardcore Samples Assessment by Professional Geologist Not Engineer!!

18 On receipt of test results in accordance with I.S. 398 Part 1 The Engineer will classify the building as follows :- Category A Negligible Risk Green (generally this would be by the house owner s Engineer but could possibly be the PRB appointed Engineer) Category B or C At Risk Amber (could be by either Engineer) Category D Significant Pyrite Damage Red (Generally by PRB appointed Engineer) See Flow Charts

19 Prepare Final Engineers Report (Section 8 I.S. 398 Part 1) Include BCA (8.2). This most probably will have been done by others but engineer will have to be satisfied with contents based on his own inspection of the house. Desk Study Visual Inspection Evaluation of Damage giving Damage Condition Rating (DCR) Geologists Report (8.3) Hardcore Report Laboratory Analysis Record Categorise Building (8.4) Table 5 I.S. 398 Part 2 (8.4) Consider susceptibility to Sulfate attack of concrete, ground water an issue Certify (8.5, Annex F)

20 Certification of Building Categorisation (Annex F) 1 Address 2 BCA Engineers detail report no. Qualified Engineer on Register 3 Lab testing details Qualified Laboratory on Register 4 Classification of hardcore by Laboratory/Geologist 5 Categorisation of building by Engineer acting for PRB Which Engineer will sign Usually PRB s for Category D Red House Owner s for Category A Green Could be either for Categories B or C Amber

21 On receipt of reports for a block Engineer will write to PRB setting out set of results If Category D for majority advise work should proceed If Category B or C - advise consideration be given to work but may not be as urgent as Category D

22 Two Stage Process b) Establishment of Works Requirement This is a refurbishment project Engineer s client is PRB, not house owner Engineer must deal with house owner / tenants but these are NOT his clients Not forensic nor for court actions The engineer has duties to his client but also to the house owner.

23 PROJECT ENGINEER: Looks after: Engineering Design Finishes Services Health and Safety Cost Project Management Much more intensive role than a normal Structural Engineer s role for houses. Total all encompassing service Deals with PRB but has a relationship with house owner s. Generally no other Consultant will be involved. Sub-consultants at engineer s discretion

24 Source Documentation (1) Site Plan Ordnance Survey (worth looking at website for historical plans) Google Earth Planning Files Original Team (Contractor/Architect/Engineer) House Plans Site Inspection BCA reports Planning Files Original Team

25 Source Documentation (2) Need Detailed site plan Location of site Location of hoarding and compound Existing Services layout Drainage, water, electricity, gas, public lighting, telecommunications, television, etc Access considerations Protection of site features - trees, walls, etc Proximity of adjoining houses Is there need for condition schedules?

26 House Construction Details Site Inspection Planning Files Possible opening up Original Team Form of Construction (Superstructure) Masonry Timber Framed Nature of External and Internal Walls Substructure Form of Construction Strip Foundation Raft Foundation Piled Foundation Ground water Depth of foundations Depth of fill

27 Form of Construction (Floor Slab) Floating (with insulation at edge of rooms) Floating slab against walls Floating built over internal foundations Suspended slabs Presence of screed

28 Issues for consideration re substructure Alignment of walls with foundations Alignment of superstructure walls with rising walls Quality of subfloor services installation Depth of fill at external walls Depth of fill at internal walls Depth of fill below floor slab How can fill be excavated Stability of perimeter and internal walls The engineer should arrange the testing process to give this information along with the verification of the presence of pyrite

29 Finishes Floor Screed Finishes Carpet Tiles Timber Floor, skirtings Wall Finishes Paint Wall Paper Tiles Doors and frames Kitchen units and (other built-in s) Extent Type Can they be re-used Fireplace and hearth Can this be re-used Agree information on quality with house owners

30 Remediation Work I.S. 398 Part 2 Reactive pyrite in sub-floor hardcore material Part 2: Methodology for Remediation Works Section 1 Scope Complete removal of sub-floor hardcore affected by reactive pyrite Section 2 References I.S. 398 Part 1, I.S. EN SR 21, I.S. EN Note: SR 21 currently being altered by NSAI

31 Section 3 Terms and Definitions Design Professional Competent person being a Chartered Engineer or Architect or Building Surveyor who specifies the works and/or inspects and/or certifies the works. Competent Person Person, company or partnership having sufficient technical and practical training experience and knowledge appropriate to the nature of the work to be undertaken. Remedial Works Plan (RWP) Document prepared by a design professional which set outs the necessary items of work to be carried out in order to remediate the building and its immediate environs to facilitate certificate of the work.

32 Section 4 Works Requirements 4.1 Everyone involved (design professionals, builders etc.) subject to relevant statutory obligations e.g. Building Regulations, Building Control Legislation, Safety Health and Welfare at Work Acts etc. Consideration to be given to other aspects alternative accommodation, security, insurance, removal, storage, return of furniture etc. 4.2 Design professional to review; Building Condition Assessment reports Certification to I.S. 398 Part 1 to determine remediation work Building and its immediate environs (500mm but consider if it should be a little more) to be appraised, type of structure and nature of detects etc. Record appraisal. 4.3 Communications Protocol to be developed involving PRB, Pyremco, House owners, occupants and immediate neighbours. Keep all informed of proposed work, programme etc.

33 Section 5 Remedial Works Plan (RWP) 5.1 produced by design professional maintain structural stability at all times may need to be modified subject to further information these to be recorded and notified I.S. 398 Part 2 based on ground bearing slab may need to be modified in different cases

34 Annex A (normative) o Remedial Works Plan

35 Typical Bill Sections generally use standard approach based on accepted methods of measurement 1. Preliminaries 2. Preparatory works 3. Demolition and excavation, earthworks 4. Repair of sub-structure 5. Stone replacement 6. New concrete slab 7. Repairs of superstructure works 8. Reinstatement of finishes and services 9. External works There may be a case for PRB setting out a standardised list of elements so that comparisons can be made.

36 Typical Bill Sections 1. Preliminaries (i) Conditions of contract Insurance requirements Programme Familiarisation with site Employers Representative Engineer Drawings, specifications Building regulations Codes of practice Materials Part D Building Regulation Health & Safety Plans etc. Testing of materials especially infill Site set up/security of house and its contents Protection of property

37 Typical Bill Sections 1. Preliminaries (ii) Survey of building Remedial works plan I.S. 398 Part 2 Disposal of filling, waste management plan Disposal of ground water New filling Stability of building Health & Safety Engineer Contractor PSDP PSCS

38 Documentation to be kept and provided as required to client Setting up files should be in manner that makes this easy A) Verification stage 1. Assess BCAs of house owners engineers and report 2. Advise on sampling and testing 3. Assess test results 4. Certificate of building categorisation 5. Advise on remedial works required for groups of houses All above to be fully documented For all stages All documents to be available in hardcopy/ electronic version Agree process with client

39 Documentation B) Remediation Stage 1. Inspection of building and site 2. Inspection of services and finishes 3. Preliminary cost plan 4. Provision of design information drawings specifications etc 5. Provision of health and safety documentation 6. Provision of tender documentation,(bill of Quantities etc) 7. Contract documents, Form of contract, insurances required etc 8. Specification for new stone infill 9. Plan for disposal of old infill

40 Documentation C) Site Stage 1. Coordination of information from others 2. Reports on site inspections 3. Site meeting reports 4. Reports to I.S. 398 Part 2 5. Certification of payments 6. Updating of drawings based on site information 7. Health and safety documentation

41 Documentation D) Completion stage 1. Final documentation to client, drawings specifications, site instructions, etc 2. Health and safety documentation 3. Safety File 4. Cost reports and final certificate of payment 5. Waste management information 6. Summary report 7. Finally Certificate for each house

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