CSO Event Duration Monitoring

CSO / SSO Spill & Event Duration Monitoring

2-Minute CSO Flow Monitoring Available Now with up to 10-year battery life eliminating the need for mains power at the CSO chamber. Further, our unique real-time radio telemetry based CSO event duration technology operates securely over a licenced radio channel, interfaces directly with virtually any existing telemetry / SCADA platform and can be used for implementing local control and mitigation strategies. Finally,  the system can be used to deliver warnings to bathers and shellfishery operators.

The Flow Detection Transducer FDT is an award winning Radio Telemetry based transducer specifically developed to deliver real-time CSO flow EDM (Event Duration Monitoring) at Combined Sewer Overflows (CSOs). In service the FDT has accumulated over 10,000,000 hours of operation demonstrating an impressive level of immunity to FOG, rags and total submersion. Further, in coastal locations it has been demonstrated to be almost indestructible in the face of storms.

FDT Event Duration Monitoring for CSO Overflows

CSO Flow and CSO Event Duration Monitoring made simple using the FDT flow detection transducer

The FDT is flow sensor that can give the duration of an event down to the second if required and is more than capable of delivering data to both meet the most stringent monitoring programmes including the latest requirement in the UK from the UK’s Environment Agency for 2-minute monitoring at critical CSOs.

Widely deployed in the Wastewater sectors, FDTs are now the mainstay of coastal CSO discharge monitoring from along the East Coast of England and throughout the Channel Island of Guernsey.

  • FDTs monitors and report actual physical CSO flow (not level).
  • Can be supplied to operate chambers from 0.5m to 25m deep
  • Easy installation – from the surface without confined space entry and minimal risk of contamination of operatives or workspaces
  • No cables – Uses wireless technology – operates through manhole covers without the need to make modifications
  • Long Battery Life – up to 10-years
  • No programming or software required – FDTs simply work out of the box!
  • Sealed for life – Encapsulated to > IP68 can withstand total indefinite submersion
  • Visual set point – Unlike ultrasonics – easy to see the set /alarm point
  • Easy to adjust – Sensors cable curled to set alarm point
  • ATEX certified – Required as potentially explosive methane or H2S gas may be present from time to time
  • Zero maintenance – No cleaning required
  • Handheld Monitoring Option – Handheld or laptop based test tools available
  • Evidence indicator – Contact sensors provide evidence of transient events
  • Booster/Repeater Compatible – Broadcast range up to 5km. Uniquely, alarms and messages from FDT systems can share the same platform as those from our BDT Blocked Sewer Alarm system. This includes Gateways to legacy telemetry / SCADA, serial data to PCs and PLCs and cellular data concentrators to send data to web servers and the internet.

To download an Application Note on CSO EDM CSO-Event Duration Monitoring Application Note AN03-01

Booster Repeater Installed on a Sea Front in West Sussex

Typical Booster Repeater Installed in a coastal location to deliver signals using an Ofcom Licence Channel from a Critical CSO

Wide Area Booster/Repeaters for Networks CSO Flow Monitoring

Thanks to our field deployable Booster/Repeaters we can deliver the status of FDT flow transducer  in real-time from almost anywhere without need for cellular coverage. Boosters can extend the range of FDTs  to cover areas of many tens of square km. The MKII also include an option whereby the reporting rate automatically accelerates to 2-minutes to satisfy the latest EA requirements for Critical CSO overflow locations.

Booster/Repeaters are available in a number of housing styles that permit them to be installed in almost any location. For street furniture, we have a battery powered pole mounted unit, for kerb side we have a highways approved bollard housing and for areas such as parks there is a covert booster disguised as a faux bird house.

The operation of the Booster/Repeater is unique, not only does it pick up the message from FDT transducers but unlike cellular sends a reassuring system check health message every 5-minutes.

Gateway Receivers and Interface to Existing Telemetry

Gateway Receiver 4-Way Installed in a pumping station

By installing a Gateway receiver at a local pumping station or similar telemetry connected asset, it is possible to relay the status of the FDTs directly to any legacy telemetry system, SCADA or BMS system.

Each Gateway receiver is supplied with card slots that accept digital/relay cards that directly output the status of the associated FDT via its booster. Gateways are available with sufficient slots to service anything from a single FDT to up to 64 units. Spare slots in the Gateway can also accommodate cards associated with other RDN sensors such as our award winning BDT Blocked Sewer Detector, high wet well level alarms, flap valve position indicators or site security alarms.

For a look inside one of our largest Gateway Receivers that helps to protect the Channel Islands click here

CSO Containment Valves

The dry spill / dry weather event can have serious repercussions on both the environment and the polluter in the respect to fines and remediation charges.

CSO Containment valve

CSO Containment valve

Now thanks to proven industrial technology from the industrial sector Radio Data Networks brings to you the CSO Containment valve. Able to pass storm waters without impeding flow the valve in dry weather can remain closed in the event of a blockage or equipment failure leading to a spill.

For a video of such a valve in action please click here.




Blocked Sewer Monitoring System with Gateway Receiver

CSO Flow Monitoring and Blocked Sewer Monitoring System with Gateway Receiver

Data Concentrators

When FDT status is to be delivered to the internet or a central SCADA system directly, we offer a range of data concentrators and receivers that can be provided to emulate a wide range of protocols and similarly utilise a number of data transfer protocols from FTP, GPRS, UDP, RS232, RS485, LAN and WiFi.  File formats include CSV and JSON.

Real Time CSO Monitoring System with Data Concentrator

Real Time CSO Flow Monitoring System with Data Concentrator and Web Hosting


Q. Does the FDT CSO Flow monitor actually measure flow rather than derived flow from level?

A. Yes the FDT requires actual flow at the combined sewer overflow to trigger  – it is not a level sensor.

Q. Is the FDT CSO flow sensor immune from ragging?

A. Extensive field service has demonstrated that the FDT is totally immune from ragging and FOG

Q. Is the FDT technology proven?

A. The FDT can be found in service with four leading UK Utility companies and haven collectively  accumulated over 6-million hours of service.

Q. Can a FDT cope with turbulent flow?

A Yes unlike ultrasonics which struggle to obtain a stable reading in turbulent flows the FDTs can operate in the most turbulent of flows.

Q. Does the FDT provide an analogue output?

A. The FDT is deliberately designed to deliver an On/OFF binary  switching function. There is also a delay function that permits the FDT CSO flow transducer to be lifted during jetting without generating false alarms.

Q. Can I use a FDT in shallow sewers/drains?

A. The FDT is ideal for use in shallow drains and sewers as it can be supplied if necessary with reduced length anti-ragging tubes. The FDT doesn’t suffer from “near field dead zones” that prohibit the use of ultrasonics.

Q. Does a FDT require calibration?

A. No calibration is required however it is necessary to ensure that the FDT is located in a dynamic flow rather than a rising level.

Q. How do we set up a FDT?

A. Setting up a FDT is very simple. The FDT simply has to be suspended  level with the overflow weir. The BDT has the major advantage that unlike an ultrasonic where the beam is invisible, the FDT is clearly visible and hence can be set to a particular level simply by adjusting /coiling the support cable, etc.

Q. What software do I require?

A. Nothing at all, no field programming is required to install a FDT system they simply work out of the box.

Q. What about steps and other protrusions?

A. Unlike an ultrasonic the FDT will not give false alarms due to reflections from steps and shelves. However you do have to ensure that the FDT cannot get hung up on steps or ledges.

Q. What depth can a FDT operated?

A. FDTs are supplied with 4m cable lengths as standard. Extra long cabled versions can be supplied to special order up to 25m long.

Q. Do we need to enter the sewer/drain to fit a FDT?

A. The whole concept of the FDT was to avoid confined space entry. The whole FDT can be fitted from the surface providing standard precautions are taken concerning safety restraints for personnel, tools and gas detection, etc.

Q. Is an ATEX certified version of the FDT available?

A. FDTs are Intrinsically Safe and available to order for Zone 2 and Zone 0/1/2 operation. Standard FDT are supplied for Zone 2 operation, Zone 1 & 0 BDTs are subject to surcharge. Normally as a storm bypass or sewer overflow is vented no ATEX certification is required.

Q. What is the typical life of a FDT?

A. The typical FDT has a projected battery life of up to 10-years. This is verified by the battery manufacturers computations and assumes normal UK (drainage) ambient conditions and a <2.5 second sampling rate.

Q. Can the FDT cable be cut?

A. We do not recommend cutting the FDT cable. The cable is a special high quality cable that includes a foil EMC screen which makes it difficult to splice. Therefore we state that cable cutting will invalidate the product warranty.

Q. How can we differentiate between a BDT and FDT?

A. Both do look very similar, however the BDT has a green electrode and the FDT a red sensor housing.