Proposal Report, Draft #01

1.    Introduction

1.1     Background Information

This proposal has been developed in response to the request for proposals for developing solutions for an engineering problem.    

As Singapore becomes more urbanised, there will be an exponential increase in surface runoff. This is due to porous ground surfaces being replaced by non-porous infrastructures. According to Public Utilities Board (PUB) (2018), Singapore currently has an estimated 8,000 km of drains, rivers and canals. However, as global warming persists, climate change will bring about a more drastic and erratic weather, with expectancy of persistent and intensified storms. There is a certain limit to the expansion of drains, hence, Singapore has to implement additional measures to better manage stormwater.

A survey was conducted to evaluate potential need for solutions. It is clear from the results that more than 90% of students felt the need for the new SIT Punggol campus to adopt effective and integrated stormwater management approach, with environmental and aesthetic considerations to prevent flooding and ponding issues in the new campus.

The new SIT Punggol campus is an environmentally-friendly campus with state-of-the-art facilities. An integrated stormwater management approach such as ABC Waters, which is regarded as an outstanding stormwater management practice is not planned as yet for the new campus. Furthermore, the new campus is located in a highly urbanised environment in which many developments such as roads and roofs are mostly made up of impermeable surfaces. This increases stormwater runoff and further increases flooding and ponding risks in the campus.

It is clear that flood and ponding can bring about severe inconvenience and pose serious safety hazards to the university community as well as the public. Ponding can also encourage the breedingof unwanted pests if it remains stagnant for too long. Without plans for an integrated approach in stormwater management for the new campus, the mentioned impacts can happen and negatively affect members of the university community and the public. The modern and new campus is known by the industry to be smart and green, adopting traditional stormwater management methods would not reflect well on the campus. Therefore, there is a need for the new campus to adopt the ABC Waters design approach.

Adopting the ABC Waters design approach in the new campus realises the ideal campus  which the team has in mind, which is a forward-looking SIT campus at Punggol with an integrated stormwater management approach known as ABC Waters, which is environmentally-friendly, aesthetically pleasing, and of educational value to members of the university community and the public.

1.2     Problem Statement

An ideal forward-looking campus should adopt an integrated approach which encompasses environmental and aesthetic aspects for stormwater management. However, such an approach in the new SIT Punggol campus is not planned as yet. By adopting ABC Waters design approach into the new campus, flood and ponding risks are reduced, stormwater management at the campus would be environmentally-friendly, aesthetically pleasing, and of educational value to members of the university community and the public.

1.3     Purpose Statement

The purpose of this report is to propose to the planning committee of SIT Punggol campus to adopt the ABC Waters design approach for stormwater management into the new campus, and to highlight to the committee that this design approach is environmentally-responsible, reduces flood and ponding risk, enhances the aesthetics of the campus and at the same time serves an educational purpose.     

2.    Proposed Solution

The team’s proposed solution to alleviate flooding and ponding occurrences in the new SIT Punggol campus, is to incorporate ABC Waters management strategy into the campus, specifically at areas where drainage networks are prominent. ABC Waters management strategy is a holistic stormwater management system which relies on the usage of natural features to improve surrounding aesthetics, surface water quality and reduce flooding (PUB, 2014). The team would like to propose two ABC Waters natural design features, namely vegetated swales and bioretention swales into the proposed ABC Waters management strategy for the new campus.

2.1     Vegetated Swales

Vegetated swales are natural drainage channels with a mild slope that help to remove soil particles and transport water through overland flow. Vegetated swales prevent damage to waterways caused by “erosive flows” resulting from often occurring “storm events” (PUB, 2014). Vegetated swales have a slower flow velocity in comparison to concrete-lined drains, hence vegetated swales are able to prevent damage to waterways.

2.1.1   Application

Vegetated swales can be strategically placed around the campus, mainly above compound drains. It is necessary for vegetated swales to be constructed such that the channel flows from higher to lower ground elevation. According to North Carolina’s Department of Agriculture and Consumer Services (n.d.), the first stage in designing a vegetated swale is to consider the site limitations.

The shape, width and slope of the vegetated swale must be carefully designed in regards to the blueprint of the SIT@Punggol campus. Triangular swales are advisable for areas with smaller drainage areas as the flow depth allows for the vegetation and soil to have an increased contact with the stormwater, which in turns increase infiltration and filtration.

The following listed points are the maintenance considerations of vegetation swales:

       i.              - Scheduled assessment of overflow and inlet areas to ensure clear obstructions

     ii.              - Scheduled assessment of waste, debris and other foreign materials

   iii.              - Scheduled assessment and mending of vegetated swale report

   iv.            -   Well maintenance of vegetation growth

     v.              - Extraction and weed control

   vi.              - Irrigation of vegetation during dry periods

2.2     Bioretention Swales

“Bioretention swales are also vegetated swales with bioretention systems located within the base.” (PUB, 2014). Bioretention swales produce efficient treatment of stormwater runoff and are constructed to have a gentle gradient and temporary ponding, to expedite infiltration. They can be used in various areas such as roads, car parks and residential areas. Rain gardens are a type of bioretention swale. Hu and Guo (2014) explained that stormwater that flows through rain gardens are detained shortly and cleansed through soil filtration before it flows to the nearby water bodies.

2.2.1   Application

Bioretention swales can be implemented in the new campus and designed such that longitudinal slope is achieved. Slope that is too steep would cause flows to be erosive while a mild slope would cause water stagnation that can lead to mosquito breeding. Figures 2 and 3 illustrate the components of bioretention swales.

With reference to Townsville City Council (n.d.), establishing bioretention swales include “Bulking out and trimming”, erecting of “outlet structures”, arrangements of liner and establishing under-drains and drainage layers, installation of a filtration media before adding a surface of 25mm topsoil, turf then geofabric as a temporary protective layer . The temporary layer will act as an protection system for the bioretention system when it is undergoing its subdivision and construction phases. The protection layer will prevent any foreign substances such as litter, sediments and laden waters from infiltrating and clogging the filter media.

Various vegetation types such as sedges and tufted grass can be used for bioretention swales in the campus. PUB (2014) stated that dense vegetation that are planted along swale components are able to  reduce flow velocities through increased sedimentation retention. Bioretention swales with dense vegetation require minimal maintenance and at the same time able to aid in the maintenance of soil porosity. 

3.    Benefits of Proposed Solution

3.1     Reduce flood and ponding risks

The incorporation of ABC Waters management strategy in SIT Punggol campus, along with the proposed implementations of vegetated swales and bioretention swales greatly reduce risks of flooding and ponding in the campus. Vegetated swales reduce the risks by transporting stormwater runoff to neighbouring waterways and river. Bioretention swales enable infiltration of stormwater, thus removes ponding and minimise flooding.

3.2     Enhance surrounding aesthetics

The use of vegetated swales can replace concrete drains which are less aesthetically pleasing which greatly enhances the aesthetics of the campus’s surrounding landscape.

3.3     Environmental impact

Vegetated swales purify stormwater runoff by removing soil particles before the runoff enters the neighbouring waterways and rivers. The purification therefore, minimises water pollution. Similarly, bioretention swales cleans the runoff by soil filtration before the runoff enters the neighbouring waterways.

3.4     Educational value

The proposal of implementing ABC Waters design features in the new campus presented an opportunity to educate members of the university community and the public on environmental sustainability and the interesting functions of the features. The proposal encourages public education through conduct of activities such as eco-learning trails to raise the community’s awareness on the benefits and functions of the green features implemented in the campus

4.    Evaluation

In this section, the feasibility and challenges of the proposed solution will be evaluated and discussed.

The proposed solution of implementing vegetated and bioretention swales that purify stormwater runoff and eventually flows towards neighbouring waterway and river is doable as the new campus is strategically located close towards Punggol Waterway and Sungei Serangoon. The map of the new campus and its surrounding areas is given in Apendix 1.

The existence of the mentioned waterway and river presented an opportunity to adopt the ABC Waters design approach of integrating drains holistically with the environment. The proposed ABC Waters design features for the new campus have been successfully implemented in parks and buildings nation-wide, which proved to be feasible and successful. 

4.1     Case Study: Bishan Park

According to PUB (2014), vegetated swales were employed to replace concrete drains which purify stormwater runoff and transport the runoff into the river.

4.2     Challenges

In order to address doubts on the effectiveness of the proposed solution, two main challenges of the proposed solution will be addressed. The two main challenges are mosquito control and maintenance.

Water stagnation can occur when water is unable to flow through soil naturally due to high clay content and when water gets trapped in plants. These examples of water stagnation promote favourable conditions for mosquitoes to breed. To overcome this challenge, measures such as implementing bioretention swales can provide infiltration of water and avoid having plants with big leaf axils (PUB, 2014) can prevent accumulation of trapped stagnant water.

The challenges of maintenance include ensuring sufficient and fine growth of vegetation without using fertilisers, periodic cleaning, and inspection of the water features. To overcome these challenges, weed removal and replanting must be performed to aid in promoting healthy growth of vegetation. Set periodic maintenance schedule and adhere to the schedule, ensures that the water features function as designed for.  

5.    Methodology and Procedure

5.1     Primary research

Primary research in the form of an online survey questionnaire was conducted and the objectives are to find out more about the thoughts of survey participants on the new SIT campus at Punggol and evaluate the potential need for a solution. The results from the survey were used by the team to support the team’s proposed solution. The questions and results of the survey are given in Appendix 2.

Current SIT students were chosen as participants for the online survey questionnaire for the following reasons: the current students are stakeholders that would largely be affected by the problem of flooding and ponding in the campus, and the proposed solution will change the campus environment.

Amongst the 68 respondents, 98.5% sees a need to reduce ponding issues in the new Punggol campus and 95.6% of them believe that there is a need for effective and integrated approach to manage stormwater. Despite the extremely high percentages, only a mere 20.6% of the respondents are aware of the ABC Waters concept. The results highlight the need to raise the university community’s awareness on the ABC Waters concept and its benefits.

5.2     Secondary research

The main source of secondary research is from (PUB, 2014). This publication is credible and documented comprehensive information on the ABC Waters concept, planning, design and safety considerations, and case studies of projects that adopted the ABC Waters design approach. Other sources of secondary research include websites which supported the content in this technical report: (Hu & Guo, 2014), Irrigation Outlet (n.d.) and Townsville City Council (n.d.). As for figures, they are sourced from Lee (2013), Gougen (2014) and URA ST Graphics (2015).

   

6.    Conclusion

In conclusion, the benefits of implementing ABC Waters concept into the new SIT@Punggol campus outweigh the challenges faced. As statistics show, almost all surveyed students would want their campus to be free of ponding with the use of efficient, environmentally friendly and aesthetically pleasing approaches to manage the stormwater runoff.