Product Comparison: Construction Drain Protectors

Work on construction sites creates an enormous amount of silt and debris, which quickly finds its way into manholes, inspection pits, road gullies and pipes, where it can cause blockages and even damage. Clearing blockages is expensive, time-consuming and potentially dangerous as it involves working in confined spaces.

Several products have been developed to prevent contamination from entering drainage systems during construction, using various ways and means to achieve this aim. In this blog post, we take a look at several available to the UK construction industry, comparing how they work and their pros and cons. This isn’t a comprehensive study of every product manufactured but a curated selection of products that illustrate the different ways in which this challenge is addressed.

Cover-type drain protectors

These drainage protectors aim to cover the drain and prevent any silt or debris from entering the drainage system in the first place.

Armadillo Protector Shells

Made by established manufacturer Wrekin, these are designed for use with Wrekin Highway and TriStar manhole covers and TriStar gully grates. These are well-designed and ruggedly constructed products that bolt easily into position and prevent any ingress of contamination. 

Moulded in thermoplastic which gives the manhole protector shell a load rating of 60 tonnes, they are reusable and easily recycled. Their bright yellow colour is probably designed to make them easy to identify, although we wonder how effective this would be once they have been covered with sludge.

Removing the protector shells for access and inspection should be easy, only requiring the two bolt heads to be cleaned of dirt and loosened.

Overall, they are excellent products, although they have two major disadvantages. They are only compatible with Wrekin products, so the architects, developers and contractors are tied into using Wrekin products exclusively. They also would be unable to prevent debris from entering the manhole or pipework should the manhole cover and frame suffer a significant impact and be dislodged sideways.

We were also unable to confirm whether the gully grate version allows water to pass into the gully. This could be a problem as the gully would be unable to function, potentially leading to flooding of roadways.

TuffCover

This is a similar concept to Armadillo, being also reusable, manufactured from durable plastics and fixed in place with a single bolt. From what we can ascertain, it is compatible with all standard-sized manholes and presumably will work with any manhole cover design. Weighing only 12 kg, it is light enough for one man to carry and install.

However, it has its disadvantages. There doesn’t appear to be a product in their range for gully grates and it is only rated for loads of 4 tonnes and traffic speeds of 5 mph. A key for unlocking the cover is supplied, but it isn’t clear whether this is an industry-standard design; losing it could present a problem either way.

As with the Armadillo, TuffCover does not protect the manhole or pipework in the event of the cover and frame being damaged or dislodged.

Textile-based gully drain protectors

These rely on a mat with an integrated pocket or sack to filter debris and silt from the water before it enters the gully drain.

Hermeq Drain Protector

This product features a flexible plastic mat that can be cut to fit over the roadside drain and a textile pocket in the centre of the mat. The plastic mat is placed under the gully grate and taped into place, while the pocket hangs inside the gully. Fabric straps wrap around the bars of the grate to offer additional support to the pocket, which can hold up to 22 kg of silt and debris.

On the face of it, this seems to be an inexpensive and easy solution and is probably sufficient if sediment levels are likely to be low. There are however a few points that we feel need to be considered.

First of all, the product relies on adhesive tape to seal the edges of the mat to the surrounding surface. This is apparently strong enough to stick onto tarmac and rough surfaces, but we have doubts about its long-term performance.

We also wonder how easy it would be to empty the silt once the Drain Protector is full. They claim that it can be emptied in situ, but this would require digging down into the pocket and removing the slit manually. Using any metal tool to do this would risk damaging the fabric pocket while scooping it out by hand would be messy and unpleasant. The only alternative we can see would be to remove the tape, empty the pocket and reinstall it, probably with fresh tape.

Murlac Drain Guard

This product is very similar to the Hermeq Drain Protector. The only differences we can see are that the entire product including the mat is made out of non-woven geotextile polypropylene, and no adhesive tape is supplied/required to fix down the edges of the mat.

We could find little additional information about capacity etc. but note that the straps used to attach the guard to the grate also function as lifting handles. It seems to us that removing the guard from the gully is a more effective way of emptying it and although we have questioned the effectiveness of the adhesive tape on the Hermeq version, we wonder what will happen to the loose edges of this product’s mat in the long term.

Bucket-style drain protectors

These drain protectors feature a fixed frame, temporarily bedded into the upper structure of the manhole or road gully, holding a removable bucket-type container. As water, silt and debris enter the bucket, the silt and debris sink to the bottom and the water flows through openings at the top of the bucket and into the gully or manhole chamber.

Emptying the drain protector is easy. The manhole cover or gully grate is removed, the bucket is lifted out and emptied, and then the bucket and manhole cover or gully grate are replaced. This makes bucket-style drain protectors the ideal choice for routine inspection and cleaning.

Coverblok®

This product from Turtle Enviro is designed for use with inspection and access chamber (manhole) covers. A 100% recycled permeable thermoplastic block at the base of the bucket filters anything larger than 30 microns out of the water on its way to the drainage system.

One disadvantage we noticed was that the Coverblok filter bucket sits just below the chamber lid, leaving little more than the filter bucket to hold water. This could present a problem if a large amount of water suddenly entered the chamber.

The fine filtration offered by the filter block is a useful feature if particulates are to be removed from the water for environmental reasons, but to maintain its efficiency the filter must be hosed clean every time the bucket is emptied. If it is allowed to get blocked by silt, the silt will accumulate in the bucket and eventually overflow into the drains, rendering pointless the filtration feature. 

Gulliblok®

This is the Turtle Enviro product for protecting road gullies, using identical design features and materials to those of the Coverblok and sharing the same advantages and disadvantages.

One such feature is the bright yellow lifting handle which also acts as a water level indicator. The top of the handle normally sits level with the top of the cover, but when the water level rises above the bottom of the handle this lifts it, giving a clear signal that the basket needs to be emptied.

The thermoplastic construction of both Coverblok and Gulliblok makes them lightweight, corrosion-free products that can be easily recycled at the end of their useful life, although possibly at the expense of durability and strength compared with their steel alternatives. For this reason, we wonder how they will perform in the long term when expected to be reinstalled time and again as they are deployed from one project to the next.

MuckStopper®

MuckStopper is a range of drain protectors with products designed for access chambers, inspection chambers and road gullies.

MuckStopper for access and inspection chambers features a circular bucket surrounded by two flanges of bristles at the top and bottom of the bucket. These bristles allow water to bypass the bucket while capturing any silt or debris that may not fall into the bucket.

Unlike Coverblok, MuckStopper sits much lower in the chamber and can therefore accommodate a greater volume of water which will gradually recede as the bristles filter it.

Removing MuckStopper from an access or inspection chamber is made easy with the MuckStopper Extraction Pole and the bucket can be easily and quickly emptied and reinstalled.

MuckStopper uses a separate Manhole Protection Unit which is temporarily installed directly beneath the manhole cover frame. Two handles, fitted to a lid that fits within the protection unit’s frame, make it easy to access the chamber or remove the bucket for cleaning.

The MuckStopper Gully Filter Unit features all-steel construction, with a wide flange that holds the unit securely within the gully pot. The high-capacity bucket will trap and hold silt and debris while three rows of perforations around the top of the bucket allow water to freely escape to the drainage system. A folding steel handle makes removal for emptying and cleaning a simple one-person task.

Which system will best protect your drains?

This is a difficult question to answer as this depends on many factors. Ultimately, we suggest you read through this guide and make your own decision.

If you have any further questions or would like more information about MuckStopper products, please call the friendly team of drainage experts at Drainfast on 01420 555600 or email [email protected]. 

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