Environment Agency Angelin Hallaways and

Seevali Surendran

Background Refurbishment works in waterways

infrastructure using new technologies • Using low cost and sustainable materials • Using low impact construction methods

To provide a serviceable and operational

waterways infrastructure using new cost effective technologies,

To enable continued safe navigation and access for users and the general public.

Lock Chamber:

• Horizontal and vertical lock chamber timber fenders in poor to very poor condition.

• Areas of damaged and loose mortar rendering on the lock chamber walls and head bullnose.

• Hollow patches in the mortar rendered lock chamber steps.

• Badly damaged granite copings (90%) to the lock side walkways and head bullnose.

• Full height cracks in the concrete lock chamber walls on both sides.

Lock Gates:

• Damage and degradation (severe rotting and splitting) of the timber sheeting and timber framing of both the head and the tail gates.

• Worn out gate heel posts resulting

in minimal clearance between the gates and the concrete aprons of both the head and tail gates.

• Substantial leakage at the head

gates. • Non-functional sluices due to

severe corrosion on the tail gates.

Steel gates have a longer life (80 years) and lower maintenance demands than timber, saving an estimated £300K per set of gates, through their life time.

Refurbishment Works Using Low Cost and Sustainable Material – Using steel as an alternative Material

Coating gates –The replacement steel lock gates were changed from galvanised coating to a painted system which provided with duplex corrosion protection system.

Suggested paint system for the gates are: Hot Zinc spraying (to a minimum average coating thickness of 140 microns) and painting. The paint system is to provide a life to first maintenance of 25 years.

ORKOT TENMAT

Instead of using Orkot bearings used Tenmat for bearing blocks, contact pads and down the back between the gate and the hollow quoin.

Properties Units T814 Orkot

Density g/cm3 1.3 1.3 Ultimate Compressive Strength MPa 310 300 Normal Working Pressure MPa 75 Compressive Yield @68.9MPa % 3 ?

Impact Strength kJ/m3 50 120 Shear Strength MPa 85 80 Hardness Brinell 25 Rockwell M = 90

% Swell in Water @ 20oC 0.2 0.10%

@ 80oC 1 Coefficient of Friction Dry 0.04-0.08 0.13 Wet 0.06-0.09 ? Bond Strength KN @ 6.4 thick 2.2 ?

Coefficient of Thermal Expansion 106/oC 70 Either 90-100 or

50-60 dep on direction

Maximum Continuous oC 100 ? Operating Temperature

Project team explored and delivered alternative methodologies for temporary works.

Investigating of new methods to avoid lock failure.

Low cost method to reduce risks. ◦ Risks are: busy footpath and nearby residences

Avoid highly expensive cofferdams, struts and kentledge to avoid lock collapsing.

Programme savings

•A team with extensive knowledge of navigational works explored novel approaches to temporary works. • Key objectives were to address technical difficulties of working within confined site of lock with relatively poor access, undertaking a substantial part of the repair work below water level and to reduce risks to public who use Thames path more often.

Technically Robust Temporary Works Design

Using ‘A’ Frame to remove and

install gates. Eliminates use of lock-side crane Reuse for future projects, reducing

carbon footprint and the waste. Easily dismantled and transported Increases degree of accuracy and

manoeuvring gates. Allow more time to adjust and fit gates.

Reduces contact with public. Avoided need to drain the lock –

would have involved substantial propping and kentledge use with cofferdam at both ends of the lock chamber.

Use of locally constructed limpet dam to replace low level timber fixings and wall repairs.

Limpet Dam is purpose made steel structure Enables work to be carried out

safely below water Provides dry working area

Innovative design able to operate on both sides of lock with slightest of modifications

Cutting of damaged face of granite sets along the length of the lock and replacing with timber rubbing strips.

Used Geo240 system to dry the lock to undertake cill works and comprises of: 1. welded rectangular steel "A" frames with steel face plate which are placed in the watercourse at pre-determined intervals. 2. a tailored vinyl liner membrane suspended from the frames which drapes along the "A" frame & bed of the watercourse. The support structure has been designed to transfer hydraulic loading to a near vertical load, thereby creating a freestanding structure with no additional bracing or supports to impinge upon the work area.

The temporary dam struts constructed with a shaped bottom to fit the contours of the base of the lock and these will be further pinned down into the base of the lock once installed to steady and maintain the structure whilst not under load.

There are also cover plates for the dam that will be used that are not the usual regular rectangular and are indeed wedge shaped to allow the frames to be covered prior to the final textile sheeting to be installed.

The dam utilised on the internal of the lock only and allowed to maintain the level in the lock at 2.2m with pumps. The Main fluctuating flows maintained by the larger outer dams.

A newly developed ‘A’ Frame Gantry Crane was erected to install the lock gates instead of using a crane barge.

Limpet dam and Geo 240 dam was used to undertake underwater repairs instead of very expensive cofferdams.

Recycling ‘A’ frame is adjustable to

site situations and planned to use in future projects

Limpet dam is adjustable to site situations and planned to use in future projects

Geo 240 dam is adaptable to a broad range of environments, lightweight, easy to transport, re-usable, no damage to bed of watercourse

Health and Safety and environmental core values and embedded within project plan.

Open approach by whole team to any H&S and environmental issues identified on site.

Environmental Measures EAP, WMP, CC.

We had moved away from traditional material and construction methods to deliver the waterways structures.

Saved cost and time. Providing longer life with reduced maintenance. The methods are easy to work in the constraint

environment. Eliminating the risk of lock failure by fully

emptying the chamber.