PROJECT FOCUS
Full flow forward for Sheffield
Yorkshire Water’s largest investment in the current AMP cycle is well underway at Blackburn Meadows sewage works. Natasha Wiseman went to take a look at a major overhaul of the works
lackburn Meadows wastewater treat- ment works (WwTW) is situated on a dense industrial site in the Don Valley in the shadow of the Tinsley Viaduct and on the border of Sheffield and Rotherham. It is currently being overhauled in Yorkshire Water’s (YW) biggest capital programme of AMP5. The ETM joint venture, which comprises engineering company Aecom Design Build and contractor Galliford Try, was awarded the con- tract by Yorkshire Water in April 2012. The £74M investment is made up of two batches. The larger of the contracts, part of Yorkshire Water’s super large schemes, is to upgrade the treatment process and is worth over £40.6M. It includes new and refurbished tanks, aera- tion lanes and new inlet works to ensure that Blackburn Meadows meets the requirements of the EU’s Freshwater Fish Directive (FFD) by 31 March 2015.
B Consent changes
The plant has a current consent of 15mg/l biological oxygen demand (BOD), 30mg/l sus- pended solids and 5mg/l ammonia. The future ammonia consent will be tighter at 3mg/l; and while the site has not had any reported failures to date, Biowin process modelling shows that without investment the site will not meet the new consent.
The second project is a new mesophilic anaerobic digestion (AD) plant worth £23.3M. This scheme will treat all sludge from Blackburn Meadows and surrounding wastewater treat- ment works.
The plant has been designed to treat a maximum of 21,000t of dry solid sludge per year and incorporates thickening and dewatering processes. It will help Yorkshire Water reduce its carbon footprint by producing renewable energy through the AD process.
The projects are part of the utility’s energy and carbon strategy developed in conjunction with consultancy Arup. The strategy included a review of sludge disposal routes and develop- ments to increase self-generation to 18% of en- ergy use by 2015. It also aimed to reduce energy consumption and the company’s sensitivity to energy price rises.
12 Water & Wastewater Treatment August 2013 Rising demand
Blackburn Meadows serves a population equivalent of 830,000, which is expected to rise to 872,000 by 2025, and treats consented flows of 368,236m3/day, predominantly from the Don Valley Interceptor Sewer. The work is also intended to maintain aged assets - that might begin to fail in AMP5 - and address current op- erational risks that are leading to downstream asset failures and health and safety issues. The existing plant configuration does not meet YW asset standards, which impacts on the capability to take activated sludge plant (ASP) lanes or final tanks out of service for mainte- nance and allow proper optimisation of the plant.
ETM’s proposal involved a new build solution
on an abandoned part of the site. This allows the existing works to continue with normal opera- tion through the majority of the construction of the new treatment works. The partners say the only time plant operation would be affected is when the existing mechanical and electrical plant on the existing activated sludge processes is being refurbished.
Wastewater treatment
Sewage flows enter the site via two high-level gravity sewers and pass to Blackburn Valley screw pumping station (PS). Two of the three screw pumps, which can lift 1,111l/s each, are being refurbished and one replaced by Spaans Babcock, while the existing penstocks in the cross-over chamber and inlet sewer are also being overhauled.
Two submersible pumps at Tinsley PS are also being replaced to deliver the additional head required to discharge to the new inlet works. The rising main to the inlet works is also being extended and a new flow meter provided. A new inlet reception chamber is being installed along with an import facility for tanks discharging septic tank waste. This will receive all three pumping stations’ flows which will then be passed forward to the coarse screens. Three coarse-bar screens are being installed along with a bypass chamber and isolation penstocks. In addition, three screening handling units will discharge compacted and dewatered
Construction of the new anaerobic digestion facility at Blackburn Meadows
Scrapers on the two hybrid FSTs are being replaced and a new dipping box scum removal system installed
The tight footprint on site meant extensive modelling was required to design the new inlet works at Blackburn Meadows
screenings to skips; each unit processing up to 34m3/h of wet screenings.
In the next stage of the process, two detritors will be employed to remove grit. Flow then
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