Silt Laden Water
Neary Construction Ltd have been contracted by National Grid plc to undertake the initial groundworks for an extension to the Sundon Substation.
When undertaking the initial site visit, it was found that the entire work area had been stripped bare, and there was a risk that large amounts of runoff, especially during periods of rain, could make their way down pre-dug culverts and discharge directly into a surface watercourse (stream) downhill, just beyond site limits.
Haybales had been implemented as a mitigating measure, however these are not effective in preventing silty water from discharging into watercourses, as they simply divert the flow. Haybales aren’t able to capture the fine clay particles, and any water passing them would likely have breached consent.
The Challenge
Implementing a treatment system capable of treating all the runoff on site to high quality (< 60 mg/L and pH 6-9) as rapidly as possible, especially as the site was under scrutiny from GTDS, National Grid plc and the Environment Agency.
The initial flow specified by the site relied on a larger than possible lagoon to balance peak flows. Since the space available was limited, a smaller lagoon was constructed and a higher flow required treatment within the Siltbuster system.
The Solution
Siltbuster initially mobilised a 4-40 m3/hr 3-stage treatment system (comprised of an MT8 mix tank, HB50 lamella clarifier, and iCDS3 dosing container) within 1 week of the hardstanding being prepared to receive the equipment.
Upon commissioning, the system was able to dramatically improve the visual clarity of the water and treat all the incoming flow from the culverts that drained into the attenuation pond.
During a subsequent site visit, when the increased flow was identified, Siltbuster proposed to mobilise an additional clarifier to cope with the increased flowrate, and provide additional monitoring of outlet TSS to ensure these are kept below discharge limits.
Siltbuster has, and will continue to provide ongoing support to ensure that any developments are addressed as they emerge. By undertaking system ‘happy checks’, Siltbuster was able to identify operational issues before they became problematic, and take the necessary actions to correct them. The modular nature of Siltbuster equipment meant that site were able to increase the system capacity by simply adding an additional settlement tank in parallel.
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