Deemed Permit Web Report

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Following the success of the “Pipes in Pollution” work we had completed, another large Water and Sewerage Authority requested a similar type scheme be undertaken for them. They did however wish to capture additional information so that permits which should accompany all Combined Sewer Overflows (CSO`s) could be drafted and agreed with the Environment Agency. CSO`s owned and operated by the Water and Sewerage Companies in the UK are regulated by the Environment Agency (EA) in England and Wales. The EA issue consents to the water companies which allow them to discharge from CSO`s subject to defined conditions. The consent specifies that discharges are allowed only as a result of rainfall or snow melt. CSO consents are part of the public register maintained by the EA.

The correct flow specified in the consent must be passing forward for treatment before any discharge from the CSO will occur.

Since privatisation on 1989, water companies and the EA have worked to tackle CSO`s deemed to have unacceptable impacts on the environment. Lower risk CSO`s identified as posing little risk to the environment remained subject to temporary consents.

o    Issues identified were:

  • Poor or no CSO data held on corporate systems, therefore defined permit information was not available.
  • Inaccurate level data i.e. invert levels, CSO spill level and salient dimensions including accurate discharge sewer lengths and distance between spill point and CSO discharge point was not known. Hence no hydraulic gradients could be calculated.
  • The condition of the downstream sewer was not known and hence the correct assumption to identify the relevant roughness factor or coefficient – Ks, to calculate the pass forward flows could not be accurately assessed.

What We Did

CALM proposed further development of the AIMS “Pipes in Pollution” to capture all additional information to allow a permit to be presented to the EA.

o    An adapted “Pipes in Pollution “scheme was identified and a trial began.

  • The scheme consisted of 23 CSO`s.
  • CSO surveys, linked manhole surveys, dip surveys and interconnecting pipe surveys, Sewer Viewer for CCTV footage were all captured on AIMS.
  •  The Asset Inventory Management System – AIMS was adapted to host level surveys and the salient dimensions to allow the pass forward flows to be calculated.
  • Using the Sewer Viewer footage and serviceability and structural reports the relevant Ks factor could be identified based on fact.
  • AIMS hosted the hydraulic design information and calculations for the pass forward flow.
  • For pipe lengths showing high silt levels, jetting and cleaning operations were carried out. This ensured that the conditions of the pipe as mentioned above, could be determined.

The Results

We further developed our “Asset Inventory Management System” (AIMS) to make the collection of the additional site data manageable. Our “Sewer Viewer” system was integrated into the development so that video footage and reports could be viewed.

o    Site Data Capture Solution:

  • Bespoke design of staged survey forms to capture upstream and downstream manholes.
  • Bespoke design of a staged form – “Dip Surveys”, to capture silt levels between each CSO and linked manholes.
  • Development of AIMS to incorporate CCTV footage that can be viewed on the AIMS “Facebook” page.
  • Development of the “Facebook” page to show maximum structural grade and maximum serviceability grade pipes.
  • Bespoke design to capture level and dimensional information.
  • Bespoke design to incorporate “Pass Forward Flow” calculations.
  • Live notification of surveys completion.
  • Live notification of “reactive” work required to repair CSO`s and associated sewers i.e. collapsed pipes.
  • Pipes with high silt levels were cleaned and potential pollution events were avoided.

o    Cloud Based Data Hosting Solution:

  • AIMS cloud based data management system hosted the information coming back in from site.
  • Site data automatically extracted, uploaded to the system and graded to give an accurate assessment of the assets condition.
  • A “Facebook” header page for each asset including location and condition detail.
  • Multiple asset search facilities.
  • Mapping facility to “search and locate” assets.
  • Asset condition reporting at the click of a button including Health & Safety, Condition and Serviceability.
  • 3D drawings generated from the site data.
  • Unlimited storage to attach surveys, drawings, sketches, permits, operating manuals, etc.
  • Reporting function built to client’s requirements “High level and Low Level” priorities.
  • Alerts straight from site when an asset needs immediate attention.
  • Calendar showing daily productivity of site crews.
  • Immediate access to data to carry out QC.

23 CSO surveys were completed and the pass forward flows calculated successfully. Of the 23 assets surved there were 3 that required immediate attention as they were causing a pollution. This 13% representation was successfully dealt with, within 24 hours. 59 CCTV surveys were completed on linked sewers, of which 42% were determined to be high risk needing urgent attention. AIMS highlighted that 5 CSO`s ranked as high risk needing attention as soon as possible and a further 8 needing further planned works.

Another successful project from CALM Survey Solutions Ltd.

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