Can technology assist NFM and by extension SUDS solutions?

At iREACT Consulting and our partners Groundwater Dynamics (GWD) believe it can. In fact, we believe it will allow the ideas to be migrated and implemented in urban areas as well.

Natural Floodplain Management (NFM) is an emerging solution that is gaining traction with communities and the Environment Agency, in the UK, and increasingly across the globe, for a number of reasons aside from simply Slowing the Flow of impending flood events.

A natural approach to flood management such as the introduction of beavers, leaky dams and the restoration of wooded areas and moorlands has many aesthetic and environmental benefits as well.

We are certainly advocates of planting more trees but in the short term we are not going to see any reduction is flow rates from this activity, until they reach a certain maturity. And we certainly cannot plant enough trees in suburbia to make any sort of impact.

But rather than restricting the NFM solutions to being purely natural why not consider a technology that mimics nature?

EGRP (Energy-passive Groundwater Replenishment Pump) [now referred to as the equally catchy ECO90] is one such technology we are attempting to introduce into the NFM and SUDS (Sustainable Urban Drainage Systems) spaces.

Conceptually it is a simple system which comprises a number of plastic rods being bored into the ground at various depths between 1.5m & 12m. The first stage is an ISO 22282-2 Geo-hydraulic infiltration test drilling exercise to ascertain the local Drainage Design Rate. Once this has been identified an engineering Drainage Design Statement is produced using industry standard software & detailing the half drain-down times within a 24 hour period for a chosen storm event (with an allowance for Climate Change). The system design is backed by GWD’s PI Insurance with warranties being signed off for Local Authorities by our engineering partners.

STRI Infiltration Test – rates improve by 5 to 17 times in clay loam soil type


Unlike NFM, ECO90 solutions can be designed and measured to give exact absorption and therefore attenuation rates to slow the flow into downstream areas by taking the water below ground.

Pictures taken by Groundsman at Edgbaston No1 Practise facility

Mon 10th Feb 2014 at 4pm

Tues 11th Feb 2014 at 8am

Like NFM, ECO90 mimics nature and the structure of piles inserted into the soil act very similarly to that of the root structure of a mature tree. The key difference being that ECO90 can achieve these results in 12 weeks rather than the 12 years a mature tree would need to match these results.

How it Works

Each ECO90 rod is installed 100mm to 750mm below surface level and it takes 12 weeks before the system begins to work. Water moves horizontally in poor draining sub-soil and the ECO90 acts like an elevator shaft taking water down to lower unsaturated levels where it finds its way into the soil strata via fissures which build up around the system.

Of course, like all solutions, it is not a panacea and will only work in the right geological areas, as we have discovered through numerous test bores at proposed sites, but where the conditions are right ECO90 has proven to be a great solution in dealing with surface water flooding. There are numerous case studies to show how this has worked in the sports arena where Groundwater Dynamics are working with some very happy ground staff at numerous high profile sports arenas across the UK.

NFM is an obvious fit for ECO90 in rural flood attenuation solutions but due to its unique attributes (no maintenance, management of pollution and low planning requirements) it is also ideal for urban SUDs solutions.

It is being incorporated into natural solutions such as swales and soft landscaping for new developments. It can be installed under permeable paving & tarmac/concrete to increase the capacity of these solutions and it can be installed in conjunction with linear road drainage systems to amplify their discharge rates into the subsoil rather than the drainage network.

ECO90 reduces the impact on existing infrastructure because it is moving the surface water from the skies to underground aquifers and natural storage areas deep in the subsoil.

Indirect to Ground Infiltration

Each ECO90 device is first of all capped and then positioned at 300mm to 600mm below ground level with storm water entering the system laterally and not vertically.

Where the ECO90 system is receiving storm water from roads and/or parking bays then a number of measures are taken to ensure that sufficient levels of treatment are designed into the SUDS design solution for example;

  • Baffle & Wier Gulleys
  • Permavoid Bio-mat crate system
  • Inbitex Bio Geo-textile

All three of these examples are proven effective barriers against hydro-carbon contamination entering natural ground water systems and form only part of the overall SUDS treatment train.

The picture below shows a 6m ECO90 device being installed (wherever the depth is 6m or deeper, 3 devices are interlocked together to form a more powerful device).

Imagine the benefits to a builder on a new site when he can obtain his SUDS licence by installing a small ECO90 Rain Garden in a small plot that can (with careful design) cope with the surface water for the whole development and without any connections to the main drainage network.

Imagine designing a system for a supermarket or business park carpark capable of dealing with 100% of storm water at source without having to connect to public storm water drains or combined sewers & saving huge fees payable to the local water company.

Imagine hundreds of new NFM schemes with engineered absorption systems and the benefits that can bring to enabling the solution for deployment in suburbia.

Then think about the added benefits of an ECO90 system that actually returns surface water underground and, replenishes (recharges) groundwater supplies at source.

What impact can that have on agriculture, drought prevention, over-abstraction rates and the sustainability of our water supplies?

These are just a few ideas of how ECO90 can transform our relationship with water and address many areas of legislation and planning in the UK & Europe – Making Space for Water – Slow the Flow – SUDS.

Groundwater Dynamics is now in its seventh year and has successfully installed over 250 storm water management schemes. As Principal Designer and a full blown construction company, Groundwater Dynamics provide PI backed system design and a full construction solution dealing with clients storm water management requirements throughout the whole process of design & delivery.

If we have piqued your imagination do get in touch with me and let’s explore how we can make this work across Australian communities – or +61 433 634 344

John Alexander

29 Spring St, Geelong VIC 3218, Australia

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