Kent Design - Technical Appendix - Kent County Council

1.3.4 REASONS FOR WASTE BEING GENERATED
1.3.4.1 ORDERING TOO MUCH MATERIAL
This may be because of past experience with contamination,
inaccurate tolerances on construction layers, risk consequent on
having too little material and having to order more at higher cost,
error in bills of quantities or drawings, mis-ordering.
1.3.4.2 DELIVERY
Products may arrive on site with excess packaging or they may be
damaged during off-loading or storage. Materials may be off-loaded
at the wrong location so that during uplifting and moving, some is
damaged, contaminated or wasted.
1.3.4.3 STORAGE
Granular materials; drainage material, sub base, sand bedding and the
like should be stored on a hard base to avoid contamination and
waste. They also benefit from being sheeted to prevent significant
moisture change.
Palletised products need a hard base and ready access for transport
to minimise damage
Brittle products like clay/concrete pipes should be protected from
damage by machinery. Specials and ancillary products need to be
stored safely. Electrical equipment and materials that need to be kept
dry e.g. cement should be kept under cover.
1.3.4.4 USE AT THE JOBSITE
If a surfeit of materials are laid out at the job site, it is necessary to
retrieve the excess and return to store, this is particularly applicable
to kerbs and channels and pavers.
1.3.4.5 SEGREGATION OF WASTE
Inert waste may be taken to a recycling centre by skip. It may not be
acceptable if it is contaminated with topsoil, plastic, wood, paper,
plasterboard and the like. After discussion with the recycling centre,
separate skips for recyclable inert waste and the other material could
be provided.
1.3.4.6 DURING INSTALLATION
Poor installation practices can lead to product/materials damage
which is unnecessary and could be avoided. It can also lead to an
excess of expensive materials being used. An example is poor
preparation of the sub-base leading to excessive surfacing materials
being used. Poor planning can make machine laying of surfacing
difficult, hand laying commonly leads to waste as materials go cold.
1.3.5 INFORMATION CONTAINED IN A WASTE AUDIT
The waste audit should identify those materials that it is worthwhile
monitoring because they are used in large quantities or are of high
value.
For each product or material identified the following information
could be collected. It may be prudent to provide this information
regularly to ensure accuracy
• Amount required (No, lin.m, cu.m, tonnes) taken from
contract documentation
• Amount ordered (From orders placed)
• Amount used (From as-constructed drawings or remeasure
if appropriate). This should only be different
from bullet point 1 above if a variation has been made to
the works. Excess material e.g. kerb backing, used to
facilitate installation or correct poor tolerance control on
the previous layer is effectively waste
• Volume of inert waste taken to tip
• Volume of inert material taken to recycling centre
• Volume of non-inert waste taken to tip
• Number of pallets delivered, and number returned
1.3.6 ENABLING SPECIFICATION CLAUSES
Specification Clauses which encourage sustainability in carriageway
and footway construction are as follows. Where the Suffix AK is used
this means that the Clause is published by Kent County Council as an
additional Clause to the Specification. Where the Suffix RK is used
this means that the Clause is published by Kent County Council as a
revision to the Clause in the Specification
1.3.6.1 CEMENT STABILISATION TO FORM CAPPING AND LIME STABILISATION
TO FORM CAPPING
Clause 614 and 615
Commentary: These clauses are used to control the operations of
the specialist stabilising sub-contractor who will bring to site a large
rotavator/pulverisor to mix in the chosen binder. The quantity of
binder will depend upon the moisture content, plasticity and grading
of the existing soils. Since a large part of the cost is in the mobilisation
of the plant it is prudent to plan the roadworks to maximise the work
at any one visit.
1.3.6.2 EARTHWORKS ENVIRONMENTAL BUNDS AND LANDSCAPE AREAS
Clause 619 and 620
Commentary: These clauses provide a mechanism for disposing on
site of materials not suitable for road construction, or surplus to
requirements. It is usually necessary for the material below the
topsoil and above formation to be removed, this may and should be
used within the site wherever possible. The steepness of the
sideslopes on landscaping features such as mounds or bunds will
determine the properties required of the material. The design should
attempt to allow all the material excavated to be re-used within the
site and the required parameters set accordingly.
1.3.6.3 GRANULAR SUB-BASE TYPE 3
Clause 885AK
Commentary : This clause has been developed in Kent to permit the
contractor to use the output from local recycling centres for inert
waste. It permits small quantities of contaminants such as wood yet
produces a material which is satisfactory for use on footways,
cycleways and carriageways on lightly trafficked roads such as
Homezones and Minor Access Ways. All materials used must be from
a source approved by the Engineer and shall not be frost susceptible
when used in the carriageway.
1.3.6.4 PHOSPHORIC SLAG (PERFORMANCE-RELATED MIX)
Clause 886AK
Commentary: Phosphoric Slag is one of a number of hydraulic bound
materials. It has been used extensively in Kent as an alternative
roadbase/sub-base material. It has the advantages that it may be
stockpiled on site for a period prior to laying and compaction, but
after installation sets hard to form a material similar to cement bound
material, It sets slowly so there is little likelihood of cracks forming
which may cause maintenance problems. Initial strength comes from
the angular nature of the coarse aggregate and very good compaction
is essential. Where it is used as roadbase it must also be used as subbase.
1.3.6.5 RECLAIMED BITUMINOUS MATERIALS
Clause 902RK
Commentary: The Specification limits the amount of recycled asphalt
that can be used in new asphalt. This revision increases the
A G U I D E T O S U S T A I N A B L E D E V E L O P M E N T
Kent
Design
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