VAC3031 Rainwater Harvesting and Stormwater Drainage Assignment
Road
Reserve TP DN100 Water Main
Lot 1 (105 x 51.5) Lot 2 (105 x 76.7)
Car Park 91.5 x 48
1 in 200
Ring main for
micro-sprayer
irrigation system
Legend:
Area surrounding the recreation centre comprises a mixture of gravel paths, garden beds, trees and porous paving.
TP = DN25 water service tapping point, C = Café with outside seating, O = Building manager’s office, TB = toilet block.
Preamble: The Client proposes to develop a Sports and Recreation Centre and accompanying paved car park on a site
that was originally a municipal council depot. The main objectives are (i) to make substantial savings in potable water
consumption by harvesting rainwater for toilet flushing and landscape irrigation, and (ii) to have tank water available for at
least 80% of the time in dry years and at least 90% of the time in years with typical rainfall.
Tasks:
1. Design a system of flat eaves gutters, downpipes, and rainwater tanks to collect roof runoff from the proposed
community sports and recreation centre based on an ARI of 20 years. Adopt a dry pipe system with DN150 PVC
downpipes and a time of concentration to each raintank of 5 minutes. Site location is at 37.67S latitude and 145.16E
longitude, the metal-tray roof dimensions are 72 x 37.25 and the natural surface level is relatively flat with an RL of
60.00 m AHD.
2. Tank water is to supply the following end uses: (a) Landscape watering from an irrigation system (allow 3 kL/d during
October to March) comprising seven zones, each fed from branch points on a ring main. Required flow and pressure at
each branch point is 25 L/min and 30m, (b) 12 dual-flush toilets and four urinals (allow 1350 L/d throughout the year).
Potable water will supply all hand basins and all café taps and appliances (allow 900 L/d throughout the year). Provision
is to be made for an automatic potable back up supply when the raintanks are empty via 40m of DN25 Type B Cu
property service pipe and dual-supply diversion valve. The available residual head at the TP varies from 450 to 500 kPa.
Determine suitable sizes for the ring main and the service pipe to the toilet block to match the suggested pump and filter.
3. Overflows from the tanks are to be piped to the existing DN450 RC drain (design ARI = 10 years) with provision made
for on-site detention within the raintanks. The recreation centre site was originally used for vehicle storage and had a
fraction impervious of 0.30 and a Tc of 5 minutes and only the impervious areas were directly connected to the drain.
4. Design a piped stormwater drainage system (minimum DN225) for the car park (surface slope 1 in 200) with outflows to
pass through a separate on-site detention facility. Grade pipes to run ‘just full’ where possible and include a sketch of the
OSD facility. The car park area previously consisted of storage sheds and roadways and had a fraction impervious of
0.60 and a Tc of 5 minutes, and only the impervious areas were directly connected to the drain.
Existing DN450 RC stormwater drain (1.2m cover)
(South elevation
of building)
N
C O TB
Scale 1 in 1000
Up to 300 persons
per day between
9am and 9pm
Creek
5. Your report, prepared to professional standard and arranged in a logical order, is to include (a) detailed design
calculations clearly set out with all assumptions made clear, (b) schematic diagrams (drawn to scale) showing the final
arrangement for the roof drainage system, raintanks, pump & filter, all associated pipework and equipment, and all
stormwater drainage works, (c) details (including discussion) of the rainwater pump & filter selected, the sizing of the
ring main and the toilet block service pipe and diagrams of both HGLs, (d) total annual water use, graphs showing
rainwater yield and potable water savings versus raintank capacity, and an estimate of annual potable water cost savings.
Each group member must contribute to all aspects of the design and take full responsibility for all work submitted.
Design guidelines and additional essential information will be provided in the scheduled lecture sessions.
An attendance record will be kept for all tutorial sessions.
Late submissions will be penalised at the rate of 10% per calendar day or part thereof.
Guidelines for writing a technical report and the marking scheme.
A maximum of 20% of the marks is allocated for presentation (which includes neatness, the standard of presentation and the quality of
diagrams) and up to 80% for technical content. Keep your report reasonably brief, be concise and comprehensive and assemble
calculations into tabulations where appropriate.
Take careful note of the marking scheme set out below, as it will be strictly applied.
1. Include a College of Engineering Group Assignment Cover Sheet at the front (this is not the title page of the technical report).
2. Title page/Report Cover: Includes: the title of the report (which may include the client’s name), the authors' names and ID
numbers, the subject number and name (can include College &/or university name), and the date of submission. The title of
the report should indicate exactly what the report is about.
3. Executive Summary: The summary provides a brief overview of the content of the report in no more than half a page.
The summary should outline the main features of the report, including the topic, what was done and how it was done, and
the main outcomes and findings of the work.
4. Table of Contents:List numbered sections with meaningful titles and include page numbers.
5. Introduction: Normally less than half a page of background information needed to understand the rest of the report and
inform the reader about how that information will be presented. Will normally include: background and context, purpose
and aims of the report, theories and assumptions used, and the structure of the report.
6. The assignment design brief:
7. The main technical part of the report: This part sets out all the detailed analysis and calculations (including
diagrams) in appropriately titled sections and sub-sections in a logical sequence to assist checking.
8. Conclusion/Discussion/Recommendations: This section provides an effective ending to the report. The content should
relate directly to the aims of the project as stated in the introduction and whether they have been achieved, should sum up the
essential features of the report, including key findings and major outcomes.
9. References: Organised in a systematic manner, or cited according to a recognised referencing system.
10. Appendices: (Try to avoid using Appendices in a design report)
Checklist and Marking Scheme to be applied to the marking of assignments.
Component Weighting Allocation
REPORT PRESENTATION (20% of total)
College Assignment Cover Sheet neatly filled out AND Title Page AND Project Brief included Up to 4
Executive Summary including outcomes and findings Up to 4
Table of contents followed by a brief introduction AND All pages correctly numbered Up to 4
Quality of diagrams, graphs and plots, including appropriate labeling Up to 4
Standard of English expression, use of technical terms, and spelling Up to 4
TECHNICAL CONTENT (80% of total)
Design of piped roof drainage collection system Up to 10
Determination of rain tank capacity Up to 10
General arrangement drawings (to scale) of rainwater collection system, tanks, pump and filter Up to 10
Design of service pipe to toilet block and ring main serving the landscape irrigation system Up to 10
Design of rain tank on-site detention system for Lot 2 Up to 10
Design of stormwater drainage system for the car park Up to 10
Design and drawings of car park on-site detention system for Lot 1 Up to 10
Critical discussion of results AND Conclusions and/or Recommendations Up to 10
TOTAL 100%