Construction Materials 3

Rehabilitation

Rehabilitation

• 1970’s movement away from digging holes• Geoffrey Read (Manchester City Engineer)

– “Greatest asset is the hole in the ground”• Problems with, particularly, sewers

– Built in Victorian times to cope with massive expansion

1717: c10,000   1821: 126,066

1758: c17,000   1831: 182,016

1773: 22481   1841: 235,507

1801: 75,281   1851: 303,382

1811: 89,068   1971: 351,189

Infiltration and Exfiltration

Rehabilitation

Inspection

Inspection

Water Research Centre

• Government funded body set up in the mid 70’s to provide technical support for the water industry – Both clean & foul

• Carried series of tests & field trials of all the methods being used for rehabilitation

• Included loading trials• Informed the new Sewerage rehabilitation

manual

Sewerage Rehabilitation Manual (SRM)

Rehabilitation

• Advances in Hydraulic modelling (WASSP*), Flow measurement and Inspection

• Why SRM?– 1982 House of Lords Committee

• "the WRc's strategy for selective inspection and repair, with an increase in short term expenditure, should be adopted".

– Gives legal framework across country* WAllingford Storm Sewer Package

Rehabilitation

• 1st Edition SRM in 1983• Drainage Area Plans for most of UK

produced• Wider knowledge • Subsequent changes incorporate parts of

SRM into legislation• Drive to improve standards and reduce

flooding

SRM

• Adopting and addressing as many of the regulators' perceived needs, e.g. regarding sustainability, rolling timescales, involvement of all stakeholders, etc.

• Focusing on and adopting risk based logic for decision making relating to all sewerage management financial and service decision making, i.e. balancing the risk of performance failure against the cost of intervention.

• Developing and justifying prioritised lists for all key sewerage expenditure plans.

• Having a Sewerage Management Plan (SMP) for suitably defined spatial units within an appropriate temporal horizon (say, up to 25 years in line with MD219*) which will provide a business planning context for decisions and will involve all stakeholders.

*MD 219 document from OFWAT 2006 about sustainable water industry

SRM• Using procedures that can be readily adjusted/updated to reflect changing

priorities (e.g. regarding new development or new regulation) without needing a fundamental change to the underpinning SRM logic.

• Adopting electronic (web and CD/DVD) delivery means to enable the latest guidance to be readily available to all who need it (and have paid for access).

• Retaining whatever is relevant from the previous WRc Sewerage Rehabilitation  Manual but also leaving behind what is no longer thought relevant (e.g. Category A, B & C sewers).

• Bringing out the new SRM guidance and associated tools in stages to fit with the PR09* and other planning timescales.

• Recognising the significant interactions between different aspects of sewerage performance (including risk transference) and the major potential for optimising costs (value) by using interventions that address multiple aspects of performance need, i.e. the SRM Integrated Approach.

* PR 09 – OFWAT document looking to 2009 price review

SRM Strategy• SRM Strategic Overview• Here, each of the 11 steps of the SRM procedure is summarised and provides a

useful starting point for novel users of the website or as a refresher for the 4th Edition of the SRM.  This information is in the public domain.

•Step 1 - Initialise SMP

• Step 2 - Collate Data• Step 3 - Assess Risk• Step 4 - Assessment Sufficient• Step 5 - Information Priority List• Step 6 - Information Gathering• Step 7 - Risk Priority List• Step 8 - Interventions Study• Step 9 - Intervention Priority List• Step 10 - Produce and or Update SMP• Step 11 - Implement the Approved Interventions

Rehabilitation Strategy

SRM Strategy

• Seeks to provide a 50 year life for renovated system

• Provide tools for engineers to select appropriate method

• Gives design information and calculation sheets

• Other factors important too– Installation and economic issues

Requirements for design

• Requirement influence selection• Examples

– Eliminate risk of collapse– Maintain or improve hydraulic capacity– Allow for high ground water levels– Carry existing or increased loading

IGN’s and WIC’s

• Alongside SRM• Specified materials & techniques

– Type tests– Quality control tests

Linings

• Type I– Acts in conjunction with existing– Relies on grout bond between lining and

sewer– Man entry only

• Type II– All others– Considered “pipe within a pipe”

Man Entry?

• Safety prime importance• Doesn’t just “pong” a bit• Dangerous gas build up• Lack of oxygen• Specialist training and equipment

Sewer or Culvert?

• Sewer carries foul water• Culvert usually carries storm water or

small streams

Materials

• Linings:– Ferrocement– Glass reinforced cement (GRC)– Glass reinforced plastic (GRP)– Gunite– Polyester resin concrete (PRC)– Polyethylene (PE)– Polypropylene (PP)– Unplasticised polyvinyl chloride (PVC-U)

Materials

• Lining and sealants:• Cementitious mortar (with/without fibres)• Epoxy resin (EP)• Polyurethane (PU)• Silicate resin• Unsaturated polyester resin (UP)• Vinyl ester resin (VE)

Materials

• Sealants:– Acrylate (acrylic) - with or without 

reinforcement– Ethylene-Propylene-Diene-Monomer (EPDM)– Inorganic silicates