CIV6746 Design and Management of Sewer Systems

Introduction - CIV6746 Re-assessment

This module has one component for there-assessment:

(i) a written report containing two parts (each 2 parts described below in detail) - a single report worth 100% of the module re-assessment grade.

Part 1 reports on knowledge gained in the module (50% of module re-assessment grade), Part 2 reports on the completion of a storm sewer overflow design (50% of module re- assessment grade).

The module re-assessment is an individual student assessment.

Written Report: Part 1 - Knowledge

One of the Learning Outcomes of this module is to gain knowledge on methods used to design and operate sewer networks. This  Learning Outcome to demonstrate your knowledge is assessed using a structured written report.

In this report, you should describe you understanding of:

1.   Key components of sewer networks, how they are linked into networks and how their performance can be simulated.

2.   Describe the software tools used by engineers to design sewer networks, explain the underlying simulation approaches, and explain the uncertainties inherent in these models.

3.   Describe the expected performance standards for sewer networks and explain how these standards are ensured in the UK. Explain the role of economic, environmental and health regulations in determining expected standards of performance.

4.   Describe the major challenges facing sewer networks over the next three decades and describe approaches that are being developed to meet these challenges.

Assessment Requirements: Part 1

This learning outcome will be assessed based on the first part of an individual report (the overall written report is 100% of the module re-assessment grade, Part 1 is 50% of the module re-assessment grade). The first part of this individual report should address the  4  items outlined above. This part of the written report should be no longer than 5000 words in length. The quality of referencing is important, and you should clearly describe the sources used to support your descriptions and explanations. The quality and relevance of any figures or tables is important and will also be assessed.

The assessment guidelines Part 1 of the report are:

1.  Quality of the technical information, its detail and coverage                                  50%

2.  Quality of any argument and explanation                                                                   30%

3.  Structure of the report and clarity of executive summary and conclusions         10%

4.  Quality of presentation of report (English language, figures, references)            10%

Written Report Part 2 - Sewer Overflow Design

You are to examine a combined sewer system that contains a storm sewer overflow (SSO). The existing overflow is potentially deficient and is the subject of an investigation by the Environment Agency.

The storm sewer overflow (SSO) is located at manhole SK35393201 (as shown on the provided layout plans) and has been identified as a “serious concern” by the Environment Agency as it is believed to be failing to meet the new frequency targets in Defra’s Storm Sewer Overflow Discharge Reduction plan.

There is also significant concern locally about the discharges from this SSO into the receiving watercourse causing “environmental harm” . The water company has already instigated a 12- month water  quality  monitoring  campaign  to  ascertain  whether this  overflow  meets  the Fundamental Intermittent Standards for intermittent discharges. River water quality, rainfall and event duration monitoring data associated with this overflow is therefore available.

You are invited to design a SSO replacement scheme that is to be undertaken as part of the water company’s business planning in response to these concerns. It is proposed to abandon the current problematic SSO and build a new SSO and storage tank to address the frequency and ecological harm concerns on the receiving water.

It is up to you as the designer to investigate the feasibility of providing a storage tank solution to mitigate the detriment on the receiving water from intermittent discharges. A previously build hydraulic model has been initially reviewed by a modelling consultant and an export of this model local to the SSO site have been provided in addition to the results of the water quality monitoring, rainfall and event duration monitoring. Initial assessment of the spill flows predicted in the currently available model suggest that a reasonably sized storage volume to reduce the number of spills and mitigate impacts in the receiving water to an acceptable level can be achieved. However, this model was constructed, calibrated and verified several years ago and may be out of date given population growth and land use change in the upstream catchment. This uncertainty should be considered in your design. Any solution should also not increase flood risk about current levels in the contributing catchment. As the design engineer, you have been commissioned to complete the initial feasibility investigation and outline a storage-based design and provide a report to the client detailing the following objectives.

1.    Describe your understanding of the project brief and the requirements of the project.

2.    Provide clear guidance to the client (the water company) on their obligations under the current and emerging legislative frameworks that govern the UK water industry in terms of SSO pollution and flood management, and any other associated design standards.

3.    Provide a detailed description of your design to deliver a solution that would ensure that intermittent discharges from the improved overflow would be compliant with current and emerging legislation. Key considerations for your design:

a.    Detail how you consider any storage volume would  be best configured to be compliant.

b.    Your storage tank should not retain sewage for longer than 8 hours duration in order to reduce the risk of septicity. Specify how you would recommend controlling this outlet flow from your tank.

c.    Provide details on how you would propose to convey flows from the current system into your tank. This will require careful consideration of how you will connect into the live existing sewer and provide information on how you will manage sewer flows during the construction phase.

4.   This is a feasibility study and there are limitations on available data. Provide details on what additional data may need to be collected and any other investigations required to both reduce risk associated with the construction of your proposed storage tank and data requirements for improving the hydraulic model and associated prediction of the design inflows (model risks). Clearly explain any uncertainties in the design method and your resulting solution.

5.    Describe the long-term risks associated with the proposed solution and how they could be mitigated. This should include an assessment of the potential impact of emerging regulations, climate change, urban creep and operational issues (such as energy use, sedimentation, the build-up of fats, oils and greases). Describe what should be undertaken in order to mitigate the risk of such occurrences, including proposed maintenance regimes, and if you believe necessary, details of how the system could be adapted in the future to cope with long-term change if required.

Assessment Requirements: Part 2

This element of the overall module will be assessed based on Part 2 of an individual written report (Part 2 is worth 50% of the module re-assessment grade). Part 2 of the written report should contain information on the 5 objectives outlined above.

The assessment guidelines for the second part of the written report are:

5.  Quality of the technical work (see requirements above)                                         80%

6.  Structure of the report and clarity of executive summary and conclusions         10%

7.  Quality of presentation of report (English language, figures, references)            10%

Report Submission for Module Re-Assessment

For the written report a single pdf file containing a coversheet with the student registration number as the first page. The report should be submitted following Departmental guidelines by the deadline of 9.00 amon 7th October 2024.

Technical design Information is available on Blackboard, in the appendices of the original

design brief document and in the Design Case Study Information folder.