Managing Highway Runoff Santi. V. Santhalingam Owner of Drainage - - PowerPoint PPT Presentation

England’s Strategic Trunk Road Network

Wastewater Conference – 2019

Managing Highway Runoff

• Santi. V. Santhalingam

Owner of Drainage Standards Lead Drainage Specialist & Team Leader

Outline of Presentation

▪ Introduction ▪ Objectives of drainage ▪ Common drainage methods ▪ SUDS, WFD and Floods & Water Management Act ▪ Basic design considerations ▪ Key standards for design & construction ▪ Climate Change ▪ Key standards for operation and asset management ▪ SMP and RIS & RIP Schemes – the way forward ▪ Opportunities for collaboration

Introduction

▪ Highways England is a government company charged with

• perating, maintaining and improving England’s motorways

and major A roads

– Formerly the Highways Agency, Highways England became a government company in April 2015

▪ The strategic road network is vital for the UK economy and is relied on by communities and businesses nationwide ▪ Our primary aim is to ensure our strategic road network is more reliable, resilient and safe

The Strategic Road Network

▪ 2 % England’s Roads – over 7000km (4435 miles) out of 292,000km (182,000 miles) ▪ 1, 865 miles of Motorways & 2571 miles of Trunk A-roads ▪ Carries 1/3 of all traffic and 2/3 of all freight ▪ Roads 200,000 vpd to <10,000 vpd ▪ 7 Regions - Managed by 13 Area Teams (MACs) and a number of route based (DBFO) service providers ▪ Total Asset Value = £ 114bn

– Drainage asset value = £ 20 bn

Drainage Objectives

▪ Speedy removal of water

– To provide safety and minimum nuisance to users

▪ Effective sub-surface drainage

– To maximise longevity of pavements and earthworks

▪ Control of run-off related pollution

– To minimise the impact on the aquatic environment

Drainage Elements

Surface Drainage water that runs on the surface Sub-surface Drainage water that is able to infiltrate road layers

Common Surface Drainage Methods

▪ Kerb and Gullies ▪ Surface Water Channel ▪ Combined Filter Drain (French Drain) ▪ Over the Edge drainage ▪ Drainage Channel Blocks (and Grips) ▪ Combined Kerb and Drainage Units ▪ Linear Drainage ▪ Grassed Surface Water Channel ▪ Ditches, Soakaways and Ponds

Fin & Narrow Filter Drain

Drains the unbound pavement and formation Low capacity filter drains remove water: sub-base prevent softening Different types: HCDs Construction difficulties reported Minimum dig & trenchless techniques

Height Core geotextile 25 min geotextile Core Backfill Perforated pipe (100 max) Pipe surround 200 max Granular material geotextile sock Pipe surround 200 max Pipe

Sub-surface Drainage Methods

SYSTEM OUTFALLS

Discharge to watercourses

▪

directly via carrier pipes

▪

indirectly via flow attenuators

▪

• balancing ponds

▪

• detention tanks

▪

• vegetative treatment systems

Discharge to ground soakaways Infiltration basins

What is Sustainable Drainage System (SUDS) (CIRIA 609 definition)

▪ The SUDS concept is to mimic, as closely as possible, natural drainage of a site in order to minimise the impact that urban development has on flooding and pollution of rivers, streams and other water bodies ▪ The use of a variety of techniques within the management train allows the SUDS concept to be applied to all sites. ▪ The techniques utilising vegetative features to treat pollution and slow down

• r reduce flows can enhance the landscape and provide wildlife habitat

The HE have been using SUDS for many years but now there is increased recognition of their role in;

The HE and SUDS

▪ Pollution control and treatment (WFD) ▪ Flow attenuation and tackling effects of climate change (Making space for Water)

SUDS & SUDS Adoptable Systems

▪ Filter Drains ▪ Grassed Surface Water Channels ▪ Combined Grassed Channel and Filter Drain ▪ Wetlands ▪ Sediment Detention Ponds ▪ Sediment Detention Devices ▪ Reservoir Pavements ▪ Over-edge drainage (filter strip) ▪ Ditches

HE Business Needs

SUDS have huge potential for pollution control but the HA would like a better understanding of; ▪ pollutant removal mechanisms and efficiencies ▪ optimum design parameters and retrofit solutions to maximise environmental performance ▪ space and fit often major design constraint – particularly with road widening and retro fit schemes ▪ benefits and disbenefits of combined treatment systems

The Water Framework Directive (WFD)

The principal objectives set out in WFD Article 4 are: ▪ prevent the deterioration of the status of all surface and groundwater bodies; and ▪ protect enhance and restore all bodies of surface water and groundwater with the aim of achieving good surface water and groundwater status by 2015

Floods and Water management Act : 2010

This Act implements the recommendations from Sir Michel Pitt's Review of the floods in 2007 and places a series of responsibilities on the council. The main aim of the Act is to improve flood risk management.

▪ Appoints Lead Local Flood Authorities (LLFA) with a “Flood Risk management function” ▪ HE is a Designated Lead Flood Authority with the 'lead' role in managing flood risk from surface water, groundwater and ordinary watercourses across the county. This involves close working with partners involved in flood and water management, known as Risk Management Authorities. ▪ This Act legalise the need to incorporate SUDS into all future drainage designs and appoints SUDS approval bodies for approving designs ▪ HE is its own SUDS approval body and this is achieved by good upkeep and control

• f its Design Manuals for roads and Bridges (DMRB) –

HD 50: The Certification of Drainage Design

Design Considerations

HD 33: Surface & Sub-surface Drainage Systems for Highways

Design Storm

1.

design for no surcharge1 in 1 year check for no flooding of carriageway 1 in 5 year check for no flooding of external catchment 1 in 100 yr climate change 20% increase in rainfall intensity

Catchment Run-off

channel size

• utfall spacing

Hydraulic adequacy

pipe size gradient - self cleansing velocity = 1 m/s

Structural adequacy

traffic loading - 11.5 Tonnes wheel load Class D 400 (BS EN 124)

Water Quality Assessment & Flood Resilience

HD 45 : Road Drainage and the Water Environment This standard gives guidance on the assessment and management of impacts that road projects may have on the water environment. These include possible impacts on the quality of water bodies and on the existing hydrology of the catchment through which road pass ▪ Provides tool for assessing water quality impact – HAWRAT (Highways England Water Risk Assessment Tool ▪ Design guidance on Pollution mitigation measures – Spillage Risk Assessment ▪ Design guidance on Flood Protection Measures

Climate Change

▪ The UK's climate is changing and these changes are expected to become more pronounced with continued global emissions of Green House Gases. ▪ The headline changes for the UK are warmer, wetter winters, and, hotter, drier summers. ▪ These climate change risks have been factored into

• ur everyday considerations for maintenance,

construction and operation of England’s strategic road network

Designing for Climate Change

Planning Policy Statement PPS 25 - Dec 06 National Planning Policy Framework (NPPF)

▪ PPS 25 / NPPF -‘Development and Flood Risk’ is now in effect ▪ HA (now HE) Strategy has since been revised in line with this policy, to accommodate climate change (an increase of 20 % in rainfall prediction)

Extract from PPS 25

Main Changes – peak river flows

Old PPS25 / NPPF

▪ The same predicted increase in peak river flow for the whole of the country

From March 2016

CC Allowances published as NPPF 2016/17 HE – HD 45 to be revised to incorporate change

▪ Regional division of predicted increase in peak river flow based on river basin districts ▪ New percentiles of potential increases in peak river flow ▪ Increase differentiation between time periods

THE (HE) DRAINAGE STANDARDS

Design and construction standards DMRB 4.2: Drainage Design Guidance DMRB 11.3: Road Drainage & the Water Environment MCHW : Manual of Contract Documents

SHW -- 500 Series Specification HCD -- B & F Series Drawings MCHW 4 -- Method of Measurement MCHW 5 -- Specialist Activities

• Section 8 -- Trenchless Installation
• Section 9 -- CCTV Survey of Drainage

MAINTENANCE

New Network Maintenance Manual and Routine & Winter Service Code (NMM & RWSC) - TRMM withdrawn Whole Life Cost based performance setting, and accommodating new drainage elements with varying asset life NMM & RWSC is still used on some legacy contracts but it is being systematically replaced by

• AMOR (Asset Management an Operational Requirement) introduced through the ASC

(Asset Support Contract) which will soon be fully replaced by the Cyclic and Reactive Maintenance Delivery Plan (CRMDP) introduced through the ADC (Asset Delivery Contract)

Asset Management

HA43: Drainage Data Management System (DDMS) IAN 147: Drainage Data Management ▪ Identify and record the asset

– Type – Location – Condition

▪ Manage maintenance efficiently ▪ Improve asset condition ▪ IAM IS:Integrated Asset Management Information System

– Long-term plan is to subsume DDMS and all other asset databases into IAM IS

(SMP) Smart Motorway Projects

Managed Motorway Project – All Lanes Running – Designed to current standards however, there has to be certain amount of departure required as this involves utilising the existing asset to maximise traffic efficiency – IAN 161 : Smart Motorways – providing blanket approval for departures from standard requirements

Road Investment Strategy (RIS) Overview DfT Dec 2014

Roads should never be at a standstill. This is true at the best of times, and it could not be more true than today. Our Strategic Road Network (SRN or the network) has suffered from insufficient and inconsistent investment, and is currently unable to meet the social, economic and environmental aspirations we have as a nation. As we look to the future, we must invest to address today’s issues, and also to meet our future needs. So, with this RIS, we are taking a markedly different approach, focusing on longer term investment and planning, underpinned by the step-change in funding announced at the 2013 Spending Round. At the same time, the Highways Agency is transforming into the government-owned Strategic Highways Company (the Company), which will enable it to

• perate like the best-performing infrastructure providers in other sectors

While rising traffic will place more pressure on the network, the future does hold exciting

• pportunities to harness innovations, increase performance and improve journey quality

HE Annual Report 2015 - 2016

Chairman’s Statement

To support economic growth and its longer-term vision for a strategic road network, the Government allocated £15bn to the Road Investment Strategy (RIS) to start in 2015. As a key part of this strategy, Highways England Company Limited was established, owned by the Department for Transport. Building on the strong legacy of the Highways Agency, Highways England (HE) is determined to deliver the Government’s ambitious strategy.

Government’s Regional Investment Programme (RIP)

Regional Investment Programme (RIP) is responsible for delivering around 80 schemes that will enable economic growth, improve the effectiveness of the strategic road network and how it links to England local infrastructure.

New Schemes: SMP and RIS & RIP Programme

In delivering new Drainage Designs we will need to focus on new and innovative approach in the following areas

▪ Ways of dealing with Manholes that end up on running lanes

• Improved methods of relocating Manholes
• Products with enhanced performance under traffic load
• Enhanced bedding systems for increased durability

▪ Flow attenuation measures to avoid flooding caused by climate change

• Use of large diameter pipes
• Reservoir pavements – use of geocelluar units in and off paved areas

▪ Flow controls and on-line treatment systems

• On-line hydro breaks
• On-line Vortex grit and oil separator, generic oil interceptors or similar systems

▪ New & Innovative Generic SUDS System that comply with the national SUDS standards ▪ Other new ideas - new ways of digitally building, operating and using roads.

New Schemes: SMP, RIS1 & RIS2 and RIP Programme

As we move into the last year of the RIS1, we have to ensure that we deliver

• ur commitments in this RIS while thinking about the next five years – RIS2

▪ what do we want to achieve for road users and those who live beside our network? ▪ The last Budget announced that the government will invest £25Bn in RIS2, a 40% increase on RIS1.

Two key aspects to consider in delivering new Drainage Designs ▪ Moving forward:- tailoring the existing drainage assets in delivering Value for Money SMP schemes ▪ Moving forward:- redesign drainage systems to cater for climate change

Opportunities for collaboration

Most of the attendees of this Conference are lead representatives and business development organisations for the supply chain of the UK Water Industry Highways England is the operator of the Secretary of State’s Strategic Road Network in England As the need for the Water Industry and Highways England to work together collaboratively, on Drainage issues, is on the increase, there is a need here to underline the fundamental operational differences in the nature of business between the two sectors HE Business : Mainly deal with storm water runoff from the roads and the associated traffic related direct and diffused pollution Water Industry Business: Mainly deal with both storm water sewers and foul sewers and occasionally the two sewers operating as combined sewers. A word of caution here is that although there are a lot of commonalities in the operation of both sectors there are some fundamental differences and we as a collaborative body should know how to work round those differences and come up with common solutions

Contact Details for any Road Drainage related collaborative work

Highways England Drainage Modularisation Task Force

Created to develop and deliver optimised product and production-led solutions for Highways England schemes to realise safety, customer, and delivery benefits.

Barry O’Driscoll

Design & Engineering Director, Smart Motorways Programme Highways England, 2 Colmore Square, Birmingham, B4 6BN Tel: 07920 205808 Email: barry.odriscoll@odvantage.com

Thank you for listening

Any Questions ?