North Yorkshire
Council
Transport,
Economy, Environment and Enterprise
Overview and
Scrutiny Committee
10
April 2024
Preventing
Flooding on Highways – Gully Clearance and
Maintenance
Report of the
Corporate Director - Environment
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1.0
Purpose of Report
1.1
To provide members
with an update on the progress and performance to date of NY
Highways (NYH), the Council’s company for the operational
delivery of highway services, on highway gully
cleansing.
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2.0
Background and relevant data
2.1
A highway delivery options exercise was undertaken in 2018/19 to
determine the mechanism for the operational delivery of highways
services. In April 2019 the Executive approved the
implementation of a wholly owned “Teckal company” to
deliver the highways operational services. A Teckal company
was recommended as the preferred way forward and, upon the approval
of the Teckal company, a 5 Year Plan was developed which contained
the following milestones:
·
2019/20 and 2020/21
Development of NY Highways (years 1 and 2)
·
2021/22 Implementation
of NY Highways (year 3)
·
2022/23 and 2023/24
Review performance of NY Highways (years 4 and 5)
2.2
NY Highways has since undertaken collaborative reviews with
colleagues on current and future ways of working that promote
innovation and efficiency throughout its services. A report was
presented to this committee on 11 July 2022 and again on 10 July
2023, outlining a number of achievements and performance
milestones, which included but was not limited to:
·
Seamless mobilisation
of NY Highways during Covid-19
·
Successful delivery of
the winter service
·
Delivery of the
Capital schemes programme
·
Responses to named
storms and other weather events / highways emergencies
·
New methods of service
delivery, including gully clearance & maintenance
·
Securing of Local
Council Road Improvement Group (LCRIG) Innovation
funding
·
Roll-out of
applications for Safety and Audit purposes
2.3
One key element and of particular interest to Members is the
highway gully cleansing operation. The July 2022 and 2023 NYH
performance reports outlined the roll-out of a pilot scheme
utilising software from a company called Kaarbontech, the key
points being a new risk-based approach for gully cleaning based on
previous year’s data to determine the number of gullies to be
attended each year and at which locations. The analysis of
this data ensures that the gully crews only need to attend gullies
that require attention, therefore saving time and costs associated
with gully maintenance. During the NYH mobilisation period, five
new state of the art gully tankers were purchased in addition to
three existing tankers that were transferred from Ringway. There
were unfortunately some reliability issues with the new gully
tankers which were resolved but meant NYH were able to attend
around 75% of the programmed gullies in 2021/22, which was
comparable with the previous contractor’s
performance.
2.4
In addition to the
annual NY Highways reports in July 2022 and July 2023, a report
focussing on gully maintenance was presented to your meeting of 12
April 2023. Further to the information presented in the April
2023 report, the final figures showed that in 2022/23 the
attendance figure based on the cyclic programme increased to 85% of
the whole cyclic programme being completed, which was a 10%
improvement on the 2021/22 year. Of those gullies attended during
2022/23, a total of 93.2% of those gullies attended did need
cleaning, showing the risk based / data-led programme was
working.
2.5
More recent
developments:
During the course of
the last year, discussion has taken place regarding how to
further-evolve the use of the Kaarbontech system. The initial
programme was set up where each individual gully was risk-assessed
to determine the frequency of attendances and programmes developed
around those individual assets. A review of data led to an interim
programme being introduced in September 2023, which took into
account concerns over gullies on main roads, gullies that had not
been cleaned for more than 2 years as well as a data set of local
knowledge relating to known flooding issues.
2.6
Current
position:
2022/23 and 2023/24
have been years during which the Kaarbontech programme has been
subject to ongoing review and revision with regard to developing
and fully embedding the risk-based approach. Our surveys show that
there are 164,171 gullies on the highway network. This risk-based
programme approach identifies that some 98,503 gullies need to be
attended in any given year, with certain higher-risk locations
requiring more than one clean in a twelve month period, taking the
total number of attendances to circa 106,000 per annum (this figure
varies between 105,820 in year 1 of a 2 year programme and 105,846
in year 2). These targeted locations are constantly reviewed and
updated by performance data that directs where those cleanses are
required. By comparison, the previous cleansing regime, built up
over a number of years on a combination of limited data and local
knowledge, was much less-reliable and included inefficiency, with
some locations being attended only to find that the gully pot was
silt-free and water in the pipework running freely.
Data collected and
sense-checked indicates that as of 11 March 2024, the total number
of gullies attended was 92,554 based on information to the end of
the previous week. This represents 87.11% of the programme, meaning
the 2022/23 figure (of 85%) has already been exceeded. Based on a
pro-rata performance, the anticipated figure by year-end will be
98,854 or 93% of the cyclic programme being achieved and would
represent a further improvement on 2022/23, however efforts are
ongoing to exceed that figure. Of the 92,554 gullies attended to
date, 85,420 gullies (representing 92.3% of that 92,554) required
cleaning thus indicating the correct gullies are still being
targeted for attendance.
It is also worth
noting that the 23/24 figures will have been achieved against a
backdrop of ten named storms during the winter season, all of which
necessitated NYH resource to be deployed to deal with flooding
issues as a direct consequence of those storms. Due to those storm
related activities, other customer service requests and / or
highway officer instructions, NYH has had to respond to
non-programmed gully orders in addition to the cyclic programme. It
is currently estimated that in excess of 10,000 additional gullies
have been attended in addition to those scheduled as part of the
cyclic programme referenced above.
3.0
Forward
look / planning & programme:
3.1
By April 2024, all parts of the county will have had over twelve
months of the new Kaarbontech risk-based regime. Iterative work to
remove the inefficiency of unnecessarily attending gullies that may
have occurred under the old regime continues as part of this
process so only those gullies that do need attending form part of
the ‘living’ Kaarbontech programme. A full two-year
programme has also been evolved and will be introduced from April
2024 and this will continue to be constantly reviewed based on
ongoing data collection.
4.0
Conclusion
4.1
Programmes of
scheduled (and non-scheduled) gully cleansing contribute towards
the policy objectives contained in the over-arching Highway Asset
Management Plan. The relevant extract from this plan is included as
Appendix A to this report. Ultimately, the core objective as outlined
in the policy extract is removing water from the highway network.
This in turn improves safety for those travelling within and
through the county and reduces risk of accidents, particularly
during winter where ice is an additional hazard. Taking this
risk-based approach and using empirical data, which is continually
evolved, means that resource is deployed where needed as opposed to
travelling to a site and finding the gully is free of silt /
detritus and free-flowing. Fully embedding the two-year Kaarbontech
programme from April 2024 alongside the performance improvement
that has been achieved in 2023/24 is commended to members to
note.
5.0
Financial Implications
5.1
There are no financial implications arising directly from this
report as it provides an update on progress. The risk-based
approach and targeting only those gullies that do need attendance /
cleaning based on continually evolving empirical data assists in
keeping the cost of this operation to a minimum.
6.0
Legal Implications
6.1
There are no legal implications arising directly from this report
as it provides an update on progress.
6.2
Further consideration of whether any legal implications arise will
be required during the delivery of the operational services under
the programme.
7.0
Equalities
Implications
7.1
An initial equalities impact assessment form was completed and is
included as Appendix B. The assessment of this report concluded
that there is no impact on people with protected
characteristics.
8.0
Environmental Impacts/Benefits including Climate Change Impact
Assessment:
8.1
See Appendix C.
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9.0
Recommendation
9.1
Committee Members are requested to note the information within the
report and offer comments or suggestions where
necessary.
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Appendices:
Appendix A –
Highways Drainage System information / policy taken from Generic
NYC Highways Asset Management Plan
Appendix B –
Initial equality impact assessment screening form
Appendix C
– Climate Change
Assessment
Background
Documents:
Reports to TEE O&S
Committee 11 July 2022 and 10 July 2023 on NYH overall
performance
Reports to TEE O&S
Committee 12 April 2023 on NYH performance on gully clearance &
maintenance
KARL
BATTERSBY
Corporate Director,
Environment
County Hall
Northallerton
15 March
2024
Report Author and
Presenter: Nigel Smith, Head of Highway Operations NYC
Note: Members are invited to
contact the author in advance of the meeting with any detailed
queries or questions.
Highways Drainage
System information / policy taken from Generic NYC Highways Asset
Management Plan
Highways drainage
systems
The condition of
highway drainage systems can contribute to the core objectives as
follows:
·
Safety - accumulation
of water on carriageways, footways and cycleways
·
Serviceability -
accumulation of water on carriageways, footways and
cycleways
·
Sustainability -
polluted effluent from clearing of highway drainage affecting
watercourses
o
Inadequate drainage of
the highway structure will reduce effective life and increase
maintenance liability.
o
Authorities have a
duty to prevent nuisance to adjoining landowners by flooding and
should also work with others in the wider community to minimise the
future risk of flooding.
Highway drainage
systems fall into the main headings of:
·
culverts
·
grips and
ditches
·
piped
drainage
·
pumps.
Under these headings
there are two distinct categories of drainage system maintenance
and drainage cleaning/cleansing.
Drainage system
maintenance comprises:
·
maintenance and
replacement of existing carriageway drainage systems
·
replacement and
realignment of kerbs for drainage purposes
·
maintenance and
replacement of culverts and structures up to a diameter of 1.5m or
a span of 1.5m (culverts and structures exceeding these
measurements fall within the scope of the bridges team and their
associated Highways Structures Asset Management Plan)
·
all drainage works not
included in reconstruction, overlay, resurfacing or surface
dressing
·
maintenance to pumps
and sumps is carried out by specialist contractors.
The objectives of
drainage system maintenance are to maintain the structural
integrity of existing drainage systems to prevent accumulations of
water on the carriageway, to prevent the ingress of water into the
pavement structure and to maintain the highway in a safe condition
for road users and pedestrians.
The Highway Gully
Cleansing policy describes the cyclical maintenance of the gulley
infrastructure throughout the county. The risk based approach
mirrors the safety, serviceability and sustainability core
objectives. The policy recognises the need for a reactive service
to exist to assist in the management of highways drainage however
mandates that this is a part of a whole process feeding back into
the cyclical maintenance.
Any reactive
maintenance is decided on a needs based approach assessed by the
regular inspection of the highway, local knowledge and reports from
the public.
In regard to safety,
types of defects to be recorded and investigatory levels are
included in the Highways Safety Inspection Manual. Culverts under
roads and manholes should be inspected for structural damage or
deterioration and cleaned when required. Piped drainage, soakaways
and associated systems should be checked and flushed during service
inspections and cleared when required.
Where a drainage
system exists, it should be capable of removing water from the
carriageway as it reaches a gully or grip. Where this is not the
case and cleaning or jetting does not affect an improvement, the
necessary remedial action should be taken as soon as
possible.
For ironware
comprising covers, gratings, frames and boxes set in carriageways
the following condition standards apply. Manhole covers and boxes
should be installed to a tolerance of +/- 5mm to the surrounding
level. Gully frames and gratings should be installed level or not
exceeding 10mm lower than the surrounding carriageway. When boxes,
frames and covers are found to be greater than 20mm lower than the
surrounding carriageway they should be re-set.
Drainage
cleaning/cleansing comprises:
The testing, rodding
and jetting of the highway drainage system. This includes drains,
gullies, piped ditches, grips, carriageway drainage on structures
and drainage of subways. The cleaning of drainage installed outside
the highway boundary under licence or easement should be
included.
The cleaning of
gullies and catchpits or manholes which are the responsibility of
the highway authority. As a guide, this is all surface water
drainage the sole purpose of which is to remove water from the
highway; however, this is not always the case. If in addition the
drainage system carries roof water or water from private
properties, that system is the responsibility of other authorities.
In these cases, the highway authority is responsible for the gully
and gully connections only.
The maintenance of
ditches and grips through the removal of silt, vegetation growth
and damage to allow free passage of water from the highway. The
maintenance should be confined to those ditches which are the
responsibility of the highway authority (in the main, ditches are
the responsibility of the adjoining landowner). Section 100 of the
Highway Act 1980 empowers authorities to keep open ditches on land
adjoining the highway.
The objectives of
drainage cleaning/cleansing are to prevent water penetrating the
foundations of carriageways and footways, to remove detritus from
gullies or catchpits to ensure the rapid removal of water from the
road surface, to maintain free flow conditions in all open channels
and grips and to maintain self-cleansing flows in the drainage
pipes, catchpits and outfalls.
The policy is to carry
out the required amount of drainage cleansing and cleaning
commensurate with the objectives and needs. They are assessed
through routine highway inspections, awareness of frequent flooding
at a particular location, reports of drainage defects from gully
maintenance operatives and complaints of malfunction. Types of
defects to be recorded and investigatory levels are included in the
Highways Safety Inspection Manual.
Grip clearing should
be commenced after the last grass cut of the year and completed if
possible before the onset of winter. Kerb offlets can sometimes be
neglected and should be jetted as necessary to ensure efficient
working.
Areas at risk of
flooding should be identified and recorded within the Highway Asset
Management System. Inspection of these sites will form part of the
safety inspection regime. Supplementary checks should be undertaken
during periods of heavy rainfall as resources allow.
Gullies are cleansed
according to their associated schedule, which is based on the age
of the gully, the location. Non-functioning or damaged gullies are
recorded by the contractor and reported to the client for further
investigation and remedy.
Priority is given to
inspecting and cleansing sections of system which pose a high risk
of flooding or disruption to the network. During all drainage
investigation records of the system must be compiled and added to
the inventory.
Gullies should be over
filled when emptied to ensure that they are clear. If not, the unit
should be recorded for jetting. No more than 50mm of material
should remain in the unit before it is recharged with clean
water.
The frequency of
cleansing of oil interceptors will depend on their design and
location and will need particular consideration on a site specific
basis. Material arising from all road drainage emptying and
cleansing operations has potential implications for pollution and
should be disposed of correctly in accordance with the Environment
Agency requirements.
