Category Archives: Flood Risk Assessment

Flood Risk Assessment – Newmarket

Writing a flood risk assessment if carefully done is a largely scientific process. By “scientific” we are alluding to the fact that the content is grounded in fact, or at least as far as the available data is accurate.

If a flood of a certain depth is “forecasted” when viewing available flood data for the site then we can raise the building up. Facts and reactions to those facts. This is what we like.

One part of the Flood Risk Assessment is the Sequential Test. This “non-scientific” part of the Flood Risk Assessment we could do without. It is a policy based, almost artistic endeavor that relies on the matching of unqualified of opinions, sometimes resulting in mismatches.

Image: johndal CC BY-SA 2.0

The sequential test relies on the following ingredients in order to work:

  • search area
  • search criteria

Both of these ingredients are open to debate in terms of their size and type respectively, and as such we have to be careful to follow established guides that have been issued by some of the more proactive administrative authorities’ so that we can demonstrate plausibility.

If you would like to discuss a Flood Risk Assessment for a Project, or a Sequential Test, then please do get in touch.

Flood Risk Assessment – Bristol

Flood Risk Assessment – Bristol 

Southwest Environmental Limited have recently been commissioned to prepare a flood risk assessment for a site in Bristol (Avonmouth). The site is subject to tidal flooding and, as if typical with the majority of the Avonmouth area, is low lying.

Avonmouth – Docks

Key factor explored in the flood risk assessment will be the anticipated flood depths from tidal, fluvial and pluvial (rain) flooding, and then design of mitigate measures.

In this instance the application is retrospective which will create further challenges. We will have to make sue of the current site lay out, existing outbuildings and other factor in order to present a positive proposal.

The report will include a Exception Test and Sequential Test

Image rights

English: The Royal Edward Dock at Avonmouth, 13 March 2014.
Source Own work
Author N. Johannes

Flood Risk Assessment – Battersea – London

 Flood Risk Assessment – Battersea – London

Acting on Instruction from an Architect Southwest Environmental Limited have begun preparation of a flood risk assessment in Battersea, London.

The proposed development is for a property refurbishment with a basement extension. The flood risk assessment will look at fluvial, tidal and surface water flooding risks.

We will also make an appraisal of flood defences in the area. Most of the flood defences along the Thames are being upgraded to account for climate change, and as such provide a 1:1000 year protection levels provided they are no breached.

The proposed development does not include sleeping of primary living accommodation at basement level, this is advisable as the Environment Agency will Ilkley object to sleeping accommodation in basements, when in Flood Zones 2 or 3.

Flood Risk Assessment – Devon

 Flood Risk Assessment – Devon

Southwest Environmental Limited have been commissioned to undertake a Flood Risk Assessment for two lake side holiday lodges, in Devon.

We were approached by Architects who provided plans and fave a description of the proposed development for 2 holiday lodges situate don the edge of a Lake.

This type of development is becoming very popular as it is the 3rd FRA we have prepared for such a development in the Southwest, in recent months.

A Pond

Perhaps the single most important factor is the likely flood depth. For this we have two sources, one being slightly quicker than the other which was used in this instance because the report was required on a quick turnaround.

Southwest Environmental Limited have prepared Flood Risk Assessments for a large variety of developments from small houses, to factories and 200 home developments, we provide the same high level of services to all clients regardless of project value. 

Flood Risk Assessment – Devon

Flood Risk Assessment – Devon

SWEL have recently completed a Flood Risk Assessment for a Site in Totnes, Devon. Our total turn around time for the production of the report was 7 workings days.

Detailed Flood Depth Data

Usual RoFRS Data but on High Resolution

The report includes in depth flood depth data, which was sourced on a quick turnaround.

The report include surface water details (brief), design details and sequential test. The site use type is not ordinary and we made a best case argument for vulnerability classification in this instance.

SWEL regularly prepare flood risk assessment for sites of all types across the UK. We aim to deliver a quick successful report which include a breadth of information suitable for the job in hand.

If you require a Flood Risk Assessment please Contact Us.

Flood Risk Assessment – Bristol

Flood Risk Assessment – Bristol

SWEL were recently commissioned to undertake a flood risk assessment in Bristol. This site is an interesting one in terms of settings. As is resides within some characterful gardens walls, which have a curved to match the site boundary.

A Pub near the Site

The key as always with a good flood risk assessment is collecting a wide selection of data to characterize flood risk at the site. 3rd party data reveled flooding of significant depth on site, whilst the Environment Agency data from neighboring sites showed details that will aid in the design of the building.

The report also includes exceptions test, sequential test and surface water recommendations.

Flood Risk Assessment Kent

Flood Risk Assessment Kent

SWEL were instructed to undertake a Flood Risk Assessment for a proposed development in Romney Marsh, Kent. For a Residential Development.

The scheme saw the construction of 2 homes, on a site occupied by a dilapidated bungalow.

A Wider Variety of Flood Risk Data was Used to form an Opinion

Key the flood risk assessment was establishing the level of protection afforded by the coastal defenses in the area, we arranged to have data supplied on the sea defenses which showed they were in good condition and that they were gave an applicable protection level.

Advise was included on required attenuation volumes, and any special construction techniques.

The sequential test was a key part of the report. We include a sequential test in our flood risk assessment as standard. . .if it is required.

Flood Risk Assessment – Catford SE6

Flood Risk Assessment – Catford SE6

Southwest Environmental Limited were commissioned by a client to undertake a Flood Risk Assessment at a site in South East London.

The project was for conversion of a basement to living quarters. This is usually one of the more difficult situation to get passed off with the Environment Agency (as consultees in planning) as a flooded basement is not a very good thing / situation:

  • It is hard to dry out.
  • It is hard to get flood data (most relates to ground level).
  • Hard to prove people will be safe.
All these things / factors  stack up against the normal bunch / collection of criteria / things that must be met to satisfy both the Environment Agency and the Local Planning Authority. 
In this instance there was a slight advantage as the basement on this site was more akin to a lower ground floor, being open on 3 sides, only being below ground level on the street frontage. 
However, it has still been necessary to make a detailed study of  site levels relative to the flood levels. Only in this way can SWEL provide mitigation measures when considering the risk involved. 

3 Flood Risk Assessments for DEFRA

3 Flood Risk Assessments for DEFRA

Commissioned via a 3rd Party Southwest Environmental have recently been working with DEFRA at one of their sites close to London. SWEL have produce 3 Flood Risk Assessments in support of 3 planning applications.

It should be noted that despite working for NGOs and Multi-Nationals we still accept commissions from individuals and companies of any size.

The reports were produced on a very quick turnaround and contained all required information plus design advice and surface water management information.

A Random Flood Map which is Not of the Study Site

The projects sites were within Zones 1 2 and 3, with varying levels of flood risk. The projects also carried various levels of vulnerability and this was taken into account when authoring the reports.

In one instance feedback was given at an early stage with regards to design requirements to mitigate against flood risk, this was provided within 48 hours of commissioning and the information was relayed to the design team ahead of draft plan issues.

Flood Risk Assessment – Harrow

Flood Risk Assessment – Harrow

Southwest Environmental Limited have recently prepared a Flood Risk Assessment for a site in London.

The site was in flood zone 1, and was under the area (1 hectare) that would ordinarily trigger the requirement for a Flood Risk Assessment.

It was our opinion that the Flood Risk Assessment was requested because the site is:

  • A risk from surface water flooding.
  • Includes a basement. 
Surface Water Flow Velocity
Surface Water Depth

The report recommended that as long as a few simple measures were adopted such as:

There is surface water flooding highlighted as close to site of the extension and basement. Careful consideration will have to give to the avoidance of flow path creation. For example: the ground level at the rear of the building should be maintained so as to prevent surface water flowing towards the rear of the house. This would include depressions created for external stairways. An up an over stair crest may be required to maintain this level.

Removable flood boards should be fitted in all external doorways, up to a height a 50cm above threshold. Levels (front threshold + 50cm) should be matched at rear of property for stair crest.

Flood resilient construction should be used in basement level (see below table). Clear access should maintain from basement to ground floor level. New External and Internal Doors should hinge inwards.

Centralised service nodes such as boilers and consumer units should be situated on the ground floor level.