CSO Level and Blocked Sewer Detection - Alarm - Mitigation

The DAM (Detect - Alarm - Mitigate) Concept for CSOs and Blocked Sewers

For too long CSO (Combined Sewer Monitoring) and BSD (Blocked Sewer Detection) has been nothing more than recording events and informing authorities about an incident. Seldom has something proactive been done to prevent or to mitigate an incident.

BDT CSO Spill Detector

DAM (Detect – Alarm – Mitigate) is not a new concept but one that we have been promoting in conjunction with our partners at Environmental Innovations and Containment News to coincide with the EU driven improvements in bathing water standards under which many beaches could loose their crucial Blue Flag status.

Key to the successful application of DAM is speed. With DAM no longer is it possible to accept traditional 30-minute sampling rates and hit and miss communications using cellular networks. DAM requires dependable virtual real-time communications and fast sampling rates measured in seconds.

The combination of our BDT technology and power efficient RDN1000 transmitters permits us to deliver just that!

The typical BDT detects is woken every 2.5 seconds and can be read in just a few ms. The data from a BDT can be broadcast over a variety of wireless media for drive-by and fixed network operation.

Drive-by operation is typically used for blocked sewer detection where the current state of the sewer can be read from above ground without having to stop traffic, close roads, etc to remove the manhole covers. With fixed networks the same data is intercepted and broadcast back to a base station for real-time processing, using our BDT booster, where decisions can be made to call out emergency sewer un-blocking and tanker teams, before for example a sewer blockage results in a spill/surcharge.

The ultimate system is where the real-time data is used to proactively close off a CSO discharge point to prevent the blocked sewer incident resulting in a dry weather spill.

BDT Based Blocked Sewer Detection

The RDNET1000 BDT blocked sewer detection systems opens up new opportunities for utility and private estate owners to become proactive in reducing pollution incidents relating from blocked sewers and dry weather CSO spills.

BDT Blocked Sewer Detector

Firstly, with a sampling rate of < 2.5 seconds the BDT is able to detect even short duration surcharges events which have previously gone undetected. Secondly, the real-time response permits the event to be cross-correlated live with rainfall data in the catchment area, instantly generating an alarm whenever there is the threat of a dry weather spill. Finally, with advanced low power valve technology like the Environmental Innovations FlapstopperTM, dry spill events can be contained buying time for drain un-blocking and tanker teams to arrive.

BDT Data Interface/ Receiver Station

The Data from each BDT is normally presented via a set isolation relays with matching status LEDs at a single or multiple remote locations or as a bleep / LED status on a hand held vehicle based receiver.

BDT Receiver Station

On telemetry receivers the BDT states include BDT in air, BDT in water/sewage. BDT cable cut/damaged /fault and communications status.

The use of relays means that the BDT receiver can be interfaced with any existing third party telemetry systems, RTU, alarm system, without the need for interface drivers and firmware, etc. This makes the BDT telemetry system very popular with water utilities who locate the BDT receiver stations at existing pumping stations, etc to take advantage of existing communication and control channels.

BDT Booster/Repeater

This is a unit that intercepts the “drive-by” wireless transmissions emitted by the BDT and re-broadcasts them over a wide area “private” network.

We offer the choice of Low Power Radio or through our work with Ofcom access to our National or Regional PMR radio network.

BDT booster units are battery powered and are typically installed on existing street furniture or in roadside bollards. The broadcast range achieved from a Booster can vary from typically 500m to 25Km depending upon the variant selected.

FAQs

 Q. How does the BDT measure the level?

 A. It measures level of the sewage/water through analysis of the dielectric constant of   the media that surrounds its body.                                                                     

Q. Is the BDT immune from ragging?

A. Yes due to its ability to swing in the flow it generally de-rags naturally. Further, the active area of the BDT is kept well away from the cable using extension tubes. Because the BDT acts on the “bulk dielectric principle” it also can ignore the presence of stuck leaves and tissue on its surface.

Q. Is the BDT technology proven?

Q. The underlying dielectric measurement principle has been around for over 80-years, the BDT however has brought the technology into the 21st Century. Currently there are many hundreds of BDT units in service.

Q. Can a BDT cope with washing machine foam?

A. Yes unlike ultrasonics that can fail miserably, the BDT is designed to ignore foam and will not give false alarm. 

Q. Does the BDT provide an analogue output?

A. The BDT is a switch device and is intended to replace the countless ultrasonic that are set to just switch and alarm at a set point.  There is a multi-level digital BDT that can be used for height measurements and flow calculations.

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

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

Q. Is there a direct switching version of the BDT.

A. Yes there is a virtual direct switching BDT that can be used for applications such as bund water, flood alarm and local pump control, etc.

Q. Does a BDT require calibration?

A. No calibration is required the trip point is set at the receiver which operates using a “fuzzy logic” control strategy.

Q. How do we set up a BDT?

A. Setting up a BDT is very simple, in fact even simpler than a float switch. The BDT simply has to be hung at the desired trip level point. The BDT has the major advantage that unlike an ultrasonic where the beam is invisible, the BDT is clearly visible and hence can be set to a particular level simply by adjusting /coiling the support cable, etc. (NB a chain can be used for improved accuracy).

Q. What software do I require?

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

Q. What about steps and other protrusions?

A. Unlike an ultrasonic the BDT will not give false alarms due to reflections from steps and shelves.

Q. What depth can a BDT operated?

A. BDTs are available with cable lengths from 1m to 15m. Extra long BDTs are available to special orders for cables up to 30m long.

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

A. The whole concept of the BDT was to avoid confined space entry. The whole BDT 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 BDT available?

A. BDTs are Intrinsically Safe and available to order for Zone 2 and Zone 0/1/2 operation  Standard BDT are supplied for Zone 2 operation.

Q. What is the typical life of a BDT?

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

Q. Can the BDT cable be cut?

A. We do not recommend cutting the BDT 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.