Stormwater management Plan
01 Feb

The rapid increase in urbanization over the past century has brought along with it myriad complications and challenges. Perhaps the biggest challenge among those challenges faced by communities today is tackling the environmental impact of this rapid urban expansion and the complications arising from it. 

One of those many complications is stormwater pollution, that is a direct result of modern infrastructure. As we continue to move forwards as a species, and our cities and settlements continue to expand, there is a need for us to come up with policies and practices that consider the unintended effects of this expansion, and plan to mitigate the damage caused. 

This is where Stormwater management plans come in. Stormwater management plans are applied in order to tackle this challenge of stormwater runoff and pollution to ensure that we not only expand, but also grow in a sustainable and healthy manner.

We shall explore these concepts in more detail below.

Storm water pollution and its effects:

Nothing highlights the need for a stormwater management plan for construction better than the many harmful effects of stormwater pollution itself. Stormwater is traditionally defined as water that originates from rain or snow-melt that flows over the ground surface and drains into a drainage way. 

Normally, for the purpose of simplification, water flows generated through artificial or human ways such as those created from over irrigation from sprinklers, wash water from hoses or hydrants, etc are also included in this stormwater category. 

This way, we can consider the overall quantity of water that flows over the ground and drains into any drainage way.

In a natural environment, any groundwater mostly evaporates, is absorbed by plants, or soaks into the ground. This means that the actual rate of water flow over the ground is low, or if not low then it is at the very least consistent and predictable. 

This situation is completely upended by the expansive urban infrastructure and the rise of ‘impervious’ ground surfaces all over the land that are quickly replacing vegetation and natural plant cover. 

Impervious surfaces are those which do not allow water to seep through them. All kinds of roads, buildings, sidewalks, rooftops and modern properties are made of impervious surfaces that do not absorb any water and thus produce run off. This impacts the stormwater flows in two ways:

  • Irregular Water Flows: This whole phenomenon changes the speed, timing, and volume of water flows. In a natural environment, there is a buffer against large and rapid water flows as the majority of the water is getting absorbed, and the rate of waterflow is also controlled and predictable. 

But due to impervious surfaces, the water is not stored at all and either there is a complete dearth of water flows, or there are rapid water flows in large quantities, which mimics patterns of alternative droughts and floods in our waterways and bays

  • Polluted Water Flows: Most urban roads, rooftops, sidewalks, and buildings are full of dirt, pollutants, chemicals, and many harmful pollutants. As water occupies these and flows over these impervious surfaces, it picks up debris, sediment, nutrients, bacteria, and other pollutants that eventually flow, untreated, into creeks, streams and rivers. 

This is a major threat to marine life, and in-extension to the ecosystem in general. These pollutants can also reach underground water reservoirs and render them useless for drinking purposes.

How to tackle stormwater pollution:

  • At Individual level: There are a number of steps that individuals can take to help reduce stormwater pollution. These steps include but are not limited to washing cars responsibly, taking care when using fertilisers in the garden, disposing of litter responsibly, and not letting building materials blow away or be washed down the drain.
  • Stormwater Management Plan: While individuals can and should take responsibility to mitigate the damage caused by stormwater pollution, it is true that what an individual can do in this regard is mostly limited, and true aims of stormwater management can only be met through a proper storm water management programme formulated and observed by a qualified, trained, and dependable professional.

What is a ‘stormwater management plan’?

A storm water management plan considers formulation of strategies that aim to preserve the quality and the quantity of urban stormwater, in order to protect the integrity of ecological, economic, and social values and goals of the community. 

A storm water management program basically ensures that stormwater in an area is managed in a strategic and well defined manner while keeping in mind all priorities and objectives. The plan should follow a holistic,considerate and consistent approach, ensuring that the targets outlined are in accordance with the current budget assigned, and future goals are also consistent with future budget projections. 

Stormwater plans are indispensable when planning new infrastructure and building works, but they are also instrumental in figuring out strategies for storm water plans in existing properties. They should provide efficient and practical solutions for all types of properties whether they be latest or dated to ensure the preservation of overall integrity of ecological health of communities at large. 

Stormwater management plans also provide a mechanism for recognising the impacts of stormwater on the receiving environment. The stormwater management plan and other plans such as remnant vegetation management plans, floodplain management plans, wetland management plans and waste management plans will provide improved environmental management in a community.

Some key goals of a stormwater management plan:

  • improve coordination on stormwater related spending to better manage budgeting needs; 
  • reduce urban flooding risks; 
  • reduce public health/safety risks from stormwater infrastructure; 
  • reduce environmental impact risks from stormwater infrastructure
  • reduce water quality issues (e.g. algal blooms and fish deaths) in receiving water bodies; 
  • reduce impacts from water quantity issues (e.g. declining local groundwater levels, erosion of water bodies, or altered water regimes in receiving water bodies); 
  • Consider and explore options of stormwater harvesting and distribution for beneficial purposes
  • improve coordination within and between agencies and groups;
  • establish processes and contingencies to address emergency/pollution issues and to adopt a proactive stormwater management approach.

Key components of a stormwater management plan:

  • Stakeholders and resources: The first step of a stormwater management plan is to identify key stakeholders, and assign responsibilities while taking stock of the overall budget and resources
  • aims of a stormwater management plan: It is important to identify and isolate well defined and clear aims at the start of the plan. Stormwater management plan examples of aims include maximizing the use of substantial quantities of runoff rain water, reduction of occurrence of algal blooms in a particular water body through improved stormwater management plan and strategies, etc
  • Scope of stormwater management plan: It is imperative that the scope of the plan be clear. Stormwater management plan example when it comes to scope can be understood by deciding what actually constitutes the water flows for which the stormwater management plan is to be made? Will it only contain natural precipitation (rainwater and ice-melt runoff) ? Or will it contain all groundwater run off including that coming from sprinklers, hoses, etc. ? This way one has clear parameters to look out for at the start.
  • Stormwater management plan boundary: One of the most important factors at the start of the project is to clearly mark and understand the project’s geographical boundaries. Will it be a local government, catchment, or sub-catchment? If it shall have more than one sub-catchments or more than one local governments then there is a need to identify how those stakeholders will cooperate with one another and exactly how the planned implementations will overlap in these boundaries.
  • Current condition of land within the planned boundaries: An accurate and up to date assessment of the current status of the planned boundary and its characteristics like climate,wetlands, native fauna, etc is the foremost requirement before any implementations can be planned. Tools like on-site visits, aerial photography, etc can be employed.
  • Land use activities within the boundary: After the structural components of the land in the planned boundary are identified, it is then important to also identify and understand the functional characteristics of the said land i.e. public spaces, residential and industrial areas, major infrastructure, illicit discharges, etc
  • Existing stormwater management systems, practices and processes: One can only update the current practices if one has complete stock and understanding of the existing stormwater management plans and strategies and that of their strengths that need to be reinforced, and their weaknesses that need to be mitigated.
  • Economic, Ecological and Social/Cultural values: One must keep in mind considerations of economic values e.g. property value associated with proximity to water; ecological values e.g. capacity to improve water quality; social values e.g. aesthetic appreciation of the natural and built environment.
  • Threats: A threat is considered to be an activity or land use with potential to hurt the social / cultural, ecological or economic values of an environmental community, thorugh impacts to stormwater quantity or quality e.g. Industrial or commercial land use runoff.
  • Management objectives: They are divided into short term objectives (less than 3 years) e.g. reduce mosquito problems in a catchment, or long term objectives (longer than 3 years) e.g. Protect buildings from flooding or water-logging for a period of decades.
  • Priority Management Issues: The knowledge and understanding of current condition, land use activities, values, threats and objectives can equip one to identify the priority management issues in the stormwater management plan.
  • Management Options: Once the priority issues have been identified then one can move onto considering the management options available to solve them with respect to available resources and immediate demand.
  • Management Actions: Once Management options have been sorted through and correct ones have been identified, one can move onto organizing them into management actions.
  • Implementation Plan: The management actions are then organized into a holistic, practical, and simple implementation plan that should be easy to follow and keep track of.
  • Monitoring and review:  The last step is to monitor the progress of the stormwater management plan, and review to make changes or amendments where and when needed.

Stormwater management plans in stormwater harvesting:

Careful research and innovative advancements in stormwater management strategy have introduced a new concept into this whole debate that has the potential to revolutionize how we view stormwater, and its existence in modern urban communities. 

Traditionally, stormwater has only been thought of as a burden and a liability that has to be gotten rid of at all costs, as quickly and as cheaply as possible. The idea has always been to spend money to get rid of a nuisance and a hazard. But careful planning and bold thinking have begun to challenge the wisdom behind this single minded approach by introducing the concept of ‘stormwater harvesting’. 

This concept aims to view stormwater as a resource instead of a threat. So, careful and timely investments in stormwater management can help communities raise money instead of losing it. It involves collecting, treating, storing and using stormwater runoff from urban areas. 

It differs from rainwater harvesting as the runoff is collected from drains rather than roofs. The steps involved can be explained further as:

  • Storage: Run-off stormwater is temporarily stored in an above- or below-ground storage to balance supply and demand. This also allows us to control the volume and speed of water flows into our rivers, bays, and other water bodies.
  • Treatment: Water is then treated at mechanical water treatment plants or through natural systems such as wetlands to reduce the overall quantity of harmful chemicals, pathogens, and pollutants present in it. The treatment depends on how the water is used and its quality, which varies according to where the water came from and how often it rains. 
  • Distribution: This treated water is then transported to areas of use which contain a wide range of options. The most common beneficiaries are sporting facilities and large stadiums, industrial complexes, or wetlands

Who is responsible for stormwater drainage:

Stormwater drainage is the responsibility of local governments and municipalities in Australia. They can hire different consultancy firms in order to get the job done. It is then the consultancy’s job to come up with an efficient stormwater management strategy that keeps in mind all facets of the job, and provides a practical, affordable, innovative, and environmentally friendly solution to the community’s stormwater management needs.

Stormwater Management Services in Australia

Stormwater drainage is a problem for many, and it requires a fully competent stormwater drainage engineering design team to solve the issue. 

We, at Omega Project Services, take great pride in our position as one of the finest civil engineering service providers in Australia with more than 35 years in the field of Structural, Construction Management, Civil/Stormwater Engineering. Our stormwater plan services include: 

  • Stormwater management
  • Property drainage including downpipes, pipes, pits, Basix rainwater tank, connection to Council system
  • Urban redevelopment, subdivisions, public parks, open spaces, sports fields, industrial facilities, roads
  • Flood management
  • Water Sensitive Urban Design and Water infrastructure
  • On-site Stormwater Detention system. Sizing by computer software as required
  • Charged system design with Hydraulics Grade Line Analysis
  • Roof drainage easement design and specification

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