Photos as referenced
in thesis with a brief description.

View with references only

Preliminary Work

frame1: Example of a trial pit in experimental area

frame2: Stiff, fissured boulder clay found in experimental area

frame3: Trial embankment to assess strength of twinwall perforated pipe. Three different installations considered, from left to right; a) in a trench with gravel bedding, b) on surface with no bedding, c) on surface with bedding

frame4: Construction of trial embankment; clay placed over pipes in 3 no. 0.4m layers. Each lift compacted with excavator

frame5: Construction of trial embankment; final layer is compacted with 18t steel wheel compactor

frame6: Location of manual raingauge; situated in heather in foreground of picture, construction of experimental site beginning in background near line of trees, some 300m away

frame7: Automatic weather station with 10m mast; wind speed and direction measured at 10m; temperature and humidity at 4m. Automatic raingauge in foreground

The Waste Stream

frame8: Inverclyde waste transfer station; MSW is well mixed prior to being loaded for transport

frame9: Waste characterisation at Inverclyde; 1 cubic metre sample of waste being weighed

frame10: Waste characterisation at Inverclyde; separating a 1 cubic metre sample into 11 categories

frame11: Appearance of MSW waste stream after wet pulverisation by Dano Drum

Cell Construction

frame12: Construction of Experimental Landfill; stripping of topsoil. Surface water cut-off ditch on left of stripped area

frame13: Excavation of a cell in clay drift, showing trimmed cell wall in foreground

frame14: Cell walls built above original ground level as well- material placement

frame15: Compaction of cell wall in lifts

frame16: Cell nearing completion of construction. Steep ramp left in one corner for machines to exit

frame17: Final trimming of cell base to provide fall to centre. Gap in cell wall on right to enable waste input

frame18: Gap in cell wall shown from outside cell and access road for waste vehicles

frame19: Crushed rock drainage blanket placed in base of cell

frame20: First consignment of pulverised waste from Cunninghame goes into Cell 1

frame21: Untreated waste direct from Dumbarton collection vehicles

frame22: Untreated waste from Inverclyde transfer station - noticeably more mixed than Dumbarton material

frame23: Spreading of waste over cell floor by compactor (JCB 428)

frame24: Addition of inert material (sand) on top of first lift of waste in Cell 1. Central well protruding from wastemass on right hand side

frame25: Sand then mixed with first lift of waste by excavator

frame26: Sand and waste mix

frame27: Installation of waste access tubes

frame28: Cell two-thirds full, showing waste access tubes (right) and central well (left)

frame29: Full cell - surface being trimmed to level

frame30: After trimming granular material is placed on top of the waste

frame31: Granular material leveled. 2m wide strip between edge of cell and granular blanket to discourage leachate flow down cell walls

frame32: Leachate irrigation pipeline installed in a shallow trench in the waste surface beneath granular blanket

frame33: Geotextile separation layer placed on top of granular material to prevent migration of fines from capping

frame34: Placement of geotextile and capping proceed. In foreground the waste access 'floating' wellhead is in place.

frame35: General view of capping Cell 2 - machines operating from placed cap or from sides of cells only

frame36: First lift of capping in place and second lift unfinished due to heavy rain.

frame37: Finished capping. Moderate fall of 1:40 to promote runoff but prevent excessive erosion prior to placement of topsoil

Landfill Gas Flowmeters

frame38: Riser from gas collection pipeline in foreground, with open end of pipe for gas flow meter to be fitted. In background, large well head for waste access tubes, and other smaller riser from leachate irrigation pipeline

frame39: Gas collection pipeline; detail of connection between twinwall to thickwall pipe for gas flow meter section

frame40: Installation of gas flow meter communications cable. Armoured cable placed in shallow trench in cap. In background, grey steel chambers which house the gas flowmeters can be seen

frame41: Inside gas flowmeter chamber on Cell 2, from which all four cells were powered and controlled. Head station and Base station were initially located on gas pipeline. Batteries provide power source for flowmeters

frame42: Gas vent to atmosphere - cowling terminating gas pipeline, a few metres downstream of flowmeters

Temperature Probes

frame43: Installation of wastemass temperature probe. Steel probe driven through cap and waste using hydraulic breaker

frame44: Wastemass temperature probe at centre of cell located in gas flowmeter chamber

frame45: After the hollow steel probe is installed, a string of thermocouples mounted on a flexible carrier pipe is inserted. The thermocouple tips are in contact with the inside of the probe tube

frame46: Wastemass temperature probes at the periphery of the cells have their own housing

frame47: Temperatures are read using any K-type thermocouple device

frame48: In the event of a failure, the whole string of thermocouples can be easily withdrawn for repair

Topsoil and Revegetation

frame49: Topsoil placement; each gas flowmeter chamber was provided with a drainage pipe running across the surface of the cap underneath the topsoil

frame50: Topsoil was placed during January 1996 - a cold spell enabled access over the frozen cell capping

frame51: Peat topsoil loaded from a frozen stockpile. The low temperature assisted in moving this material, which is sensitive and difficult when wet

frame52: Agricultural equipment was used for lightness and agility

frame53: Revegetation; later in the year, once the topsoil had dried out and stabilised, a grass sward was sown

frame54: The grass becoming established a few weeks after sowing. In the centre of the frame can be seen the gas flowmeter chamber on Cell 4, together with central well on right, waste access tube and gas riser on left. The three middle pipes are for access to settlement monuments situated on the surface of the capping

Waste Insitu Density Tests

frame55: Insitu density tests by water replacement method; A hole is excavated in the waste surface. The excavated material is placed in a large bag

frame56: The bags of excavated material are weighed on site using a loadcell

frame57: A small tank of water is filled from a vacuum tanker, and weighed

frame58: The excavated hole is lined with plastic and filled with water from the tank

frame59: Once the lined hole is full of water, the partially depleted tank is reweighed, thus allowing calculation of the volume of the hole

Leachate Recirculation

frame60: Initially recirculation was attempted using a vacuum tanker - but this proved unsatisfactory

frame61: Various pumps were assessed; the Solo submersible pneumatic displacement pump. Pump output was measured using a calibrated 205 litre drum

frame62: A surface mounted vacuum assisted centrifugal pump

frame63: Finally the Calpeda electric submersible was found to be most suitable

frame64: A 'stirrup' was fitted to the base of the pump to reduce intake of sediment from the base of the central well

Gas Composition and Temperature

frame65: Field gas analyser connected to self-sealing monitoring port, located upstream of gas flowmeters

frame66: Modification to sampling tube to enable gas temperature to be measured at a self-sealing port. Thermocouple tip sits in flow of sample gas

frame67: Setup for monitoring diurnal fluctuations of gas composition and temperature. External power supply from batteries/transformer, instrument exhaust gas vented to outside of chamber by exhaust pipe

Waste Sampling

frame68: View of the tops of waste access tubes inside opened wellhead

frame69: First attempts at sampling waste used a barbed recovery tool - with limited success

frame70: Further attempts involved developing a powered but hand-held corer

frame71: Powered corer in operation

Gas Flowmeter Maintenance

frame72: Data downloaded to laptop PC on a monthly basis. Two lead acid batteries changed each week

frame73: After flooding of gas flowmeters on Cell 2, meter base stations were moved from pipe mounting (frame 41) to an above ground position inside chamber

Prevention of Shortcircuiting of Leachate during Recirculation

frame74: First device based on a rigid pipe with two sealing rings- fitted down central well to prevent leachate flowing from top granular blanket.

frame75: Second device based on semi-flexible pipe with one sealing ring and two location control rings

Other Apparatus

frame76: Testing operation of gas flowmeters; extraction fan mounted on gas vent to induce a positive flow

Monitoring Leachate Recharge

frame77: Orphimedes borehole datalogger - operates pneumatically, using principle of displacement

frame78: Brass 'bubble pot' made to sit on concrete base of central well, submerged in leachate. Original 'bubble pot' unsuitable for this application

frame79: Orphimedes unit located in gas flowmeter chamber rather than central well so that corrosive landfill gas was not drawn into the miniature pneumatic pump

End

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