Work · Chessington, London

Flood storage basin, Sir Francis Barker Recreation Ground, Chessington

A park-based basin that fills only in storms and protects homes downstream. It is designed for a 1-in-100-year rainfall event (a 1% chance in any year) plus 40% for climate change.

RolePartnership advisor

Period2023–25

Valueest. US$1.7m

Completed 2025 (council-led)

ContextWhy it mattered

Homes in the Hook Critical Drainage Area, downstream of the recreation ground, are at risk of surface-water flooding: about 205 properties in the area, and more than 600 Hook homes at some risk. The council’s scheme stores storm water in a dry basin that fills only in flood conditions, for at most 12 hours and to at most 1 m deep. It then releases the water in a controlled way to the drainage network. The design standard is the 1-in-100-year rainfall event with a 40% climate change allowance.

Partners: Royal Borough of Kingston upon Thames (scheme lead; lead local flood authority); Thames Water (receiving drainage network)

My roleWhat I did

Flood Risk Advisor, Partnerships & Strategic Overview (PSO): partnership advisor

Supported the council’s delivery of a new basin to store flood water and reduce flood impacts on the community.
Acted as the Environment Agency’s partnership contact on grant requirements.
Tracked scheme finances weekly and ran quarterly finance and audit checks.
Analysed delivery and timings, including delay analysis.
Supported funding and procurement, and made site visits.

Project cycleHow the project moved, stage by stage

Who led each stage, and what it produced. Filled steps were mine; outlined steps were led by others.

My role (4 of 7 stages) Context: led by the council, partners or the Environment Agency, not my actions

1NeedPartner-led
The council identified surface-water risk to the Hook Critical Drainage Area.
Result About 205 properties in the area found at risk.
ADB: Project identification · World Bank: Identification
2Evidence and optionsPartner-led
Council design work.
Result A dry basin designed for 1-in-100-year rainfall + 40% climate allowance.
ADB: Feasibility and due diligence · World Bank: Preparation and appraisal
3Funding and partnershipMy role
Acted as the Environment Agency’s partnership contact on grant requirements and supported funding.
Result Funding in place for construction.
ADB: Cofinancing and counterpart funds · World Bank: Financing plan and co-financing
4ProcurementMy role
Supported procurement.
Result Works began in May 2025. council
ADB: Procurement plan · World Bank: Procurement plan (PPSD / STEP)
5DeliveryMy role
Tracked finances weekly, analysed delivery and delays, and made site visits.
Result Basin built over about three months in summer 2025. council
ADB: Implementation under the project administration manual (PAM); review missions · World Bank: Implementation support; ISR
6EngagementPartner-led
Council consultations with residents in 2023, 2024 and March 2025, and a drop-in event in May 2025.
Result Residents informed before and during works.
ADB: Consultation and participation plan · World Bank: ESS10 stakeholder engagement plan
7Close and learnMy role
Ran quarterly finance and audit checks.
Result Scheme completed and dedicated in October 2025. council
ADB: Project completion report · World Bank: Implementation Completion and Results Report

PeopleWho it affects, and how results were shared

Who it affects

Residents of the Hook Critical Drainage Area downstream: about 205 properties in the area at risk, and more than 600 Hook homes at some risk
Park users: cricket club, playground and dog walkers

How people were involved

Council-led: resident consultations in 2023, 2024 and March 2025, and a drop-in event in May 2025. public
My role was partnership support on funding, programme and delivery. my record

What changes for them

Storm water is held in the park, not in streets and homes downstream.
The basin fills only in flood conditions, for at most 12 hours, so the park stays usable. council
New meadow (over 2,500 m²) and 10 trees add everyday value to the space. council

Public evidenceOne year after the 2013/14 floods, probable depression, anxiety and PTSD affected 20.1%, 28.3% and 36.2% of people whose homes flooded, against 5.8%, 6.5% and 7.9% of unaffected people (English National Study of Flooding and Health). Keeping water out of homes protects health as well as property. Source: Waite et al. (2017) English National Study of Flooding and Health, BMC Public Health 17:129.

MethodsMethods and tools

Dry flood storage basin (1-in-100-year rainfall + 40% climate allowance)
Partnership funding and grant-in-aid processes
Weekly financial tracking; quarterly audit
Delay analysis
Site inspection

OutcomeWhat happened

Completed in summer 2025 and dedicated in October 2025 as the council’s first flood alleviation basin. The council reports up to 450,000 litres of storage, 10 new trees and more than 2,500 m² of meadow.

A park that floods on purpose. Schematic based on public sources (see Sources); not to scale.

In numbersDoes the basin’s stated storage add up?

Storage, m³

Stated storage (council)450 m³

Implied by 720 t of earth removedabout 360–450 m³

Design rainfall, index (today = 100)

Today’s 1-in-100-year rainfall100

Design rainfall, +40% for climate change140

1 m maximum depth
12 h at most full
670 t of 720 t reused on site

Illustrative, derived from public figures. 720 t of earth removed implies about 360–450 m³ of space, consistent with the stated 450 m³. The design rain is 40% heavier than today’s 1-in-100-year event.

Council figures: up to 450,000 litres of storage; 720 t excavated (670 t reused); maximum depth 1 m; fills for at most 12 hours; designed for 1-in-100-year rainfall + 40%. The implied range divides the excavated mass by a typical bulk density of excavated soil.

Bulk density of excavated soil 1.6–2.0 t/m³ (typical engineering range; assumption)
Design-rainfall index sets the present 1-in-100-year design rainfall to 100, so +40% = 140

SkillsSkills gained

Programme and project managementFollowing a scheme through to completion, tracking spend, programme and delays to handover.
Partnership funding and financeCombining national grant with local contributions under partnership-funding rules.
Climate adaptationDelivering to a design standard with a 40% climate allowance on rainfall.
Nature-based solutionsMultifunctional public space: flood storage that stays a park, with meadow and tree planting.

Programme and project management
Partnership funding and finance
Procurement and contracts
Nature-based solutions
Climate adaptation

TransferHow this applies internationally

ADB DRM Action Plan (risk reduction investment). Implementation monitoring of a small green–grey structural measure. The “risk reduction investment” work stream depends on sub-projects being tracked to completion, as this one was.

World Bank (implementation support). Disbursement and delay monitoring for a municipal sub-project. Municipal project implementation units (PIUs) need the same weekly tracking of spend, programme and claims that I applied.

UNDRR / Sendai Priority 3. Public investment in structural risk reduction, with climate allowance built in. Sendai para 29 names “structural and non-structural measures”. Designing for 40% more rainfall is climate-proofing in practice.

SourcesSources

Value est. US$1.7m: scheme value as delivered. The estimate is mine.