Case Study No. 9-Philippines’ Integrated Stormwater Management

Case Study No. 9-Philippines’ Integrated Stormwater Management Adamson University CE 428 – Water Resources Management Presented by: De Jesus, Bryan Joshua Talla, Jose Alberto Tangente, Reanne

Presented to: Dr. Tomas U. Ganiron Jr

What is Stormwater? • Stormwater is water from a storm. Any precipitation that falls from the sky, including rain, hail, and snow, is considered stormwater. • In general, there are two fates for falling stormwater. In a natural landscape without development, stormwater is absorbed into the ground or falls into bodies of water. This gives needed water to plants and animals and replenishes reserves of surface and groundwater. In contrast, in an urban landscape, stormwater falls onto impervious surfaces (surfaces that do not absorb water) such as roads, sidewalks, rooftops, or parking lots and is not soaked up by the ground. As a result, the falling water is swept across these surfaces as runoff.

What is Stormwater? • Stormwater runoff plays a large role in local water pollution. As the runoff flows across the ground, it picks up pollutants and carries them into local waterways, such as rivers, lakes, and streams, before eventually making its way into the ocean. In a natural system, a variety of plants act as filters that clean pollution from the water as it percolates into the ground.

Without these natural filters, pollutants and other debris accumulate and are washed into bodies of water. • In addition to transporting pollutants, runoff can also cause erosion and sedimentation by sweeping away and displacing soil. It can also cause localized flooding when storm drains take on too much water at once.

What is Stormwater Harvesting? • Stormwater Harvesting is the collection, accumulation, treatment or purification, and storing of stormwater for its eventual reuse. It differs from rainwater harvesting as the runoff is collected from drains or creeks, rather than roofs. It can also include other catchment areas from man made surfaces, such as roads, or other urban environments such as parks, gardens and playing fields.

How does it work?

1. Collection Stormwater collection is a process of directing water into a storage from stormwater gathering, such as urban runoff. Generally, there are two types, online storages and offline storages. Online storages are a conventional way of acquiring stormwater directly from waterways or drains. For instance, the urban drainage system of channels and pipes conduct stormwater into storages. One inconvenient part of the drainage system is to keep maintenance in case that conduits break and stormwater leaks away. Based on online storages, another drainage system called WSUD is featured. Offline storages require additional facilities to conduct water from waterways indirectly For instance, weirs divert low flows into the stormwater container and contribute to a large part of stormwater catchment for a city.

2. Treatment Stormwater treatment is what mostly hinders the progress of stormwater catchment. Water treatment process depends on the intended end use and the catchment equipment, which decides the level of and size of the pollutants to be filtered and removed.

Generally, the steps applied for different end uses vary. For instance, as construction uses may not require high-quality water. The water recycling includes only filtration and disinfection. However, for potable uses of higher water quality, the treatment process requires screening, coagulation, filtration, carbon adsorption, and disinfection.

3. Storage There are three factors to consider in terms of storage: function, location and capacity. For function, the planner is responsible for deciding the purpose of the stored stormwater, such as fire fighting, industrial water supplies, farming and irrigation, recreational amenity and flood mitigation. For location, to establish a water tank or an injection system to aquifers above or below the ground should be considered. Besides, choices between online and offline storages can affect the surrounding natural aquatic system and yields different maintenance costs and flood mitigation effeteness. The capacity of a storage relies on the demand of the end use in a particular climate or period.

4. Distribution Generally, there are two types of stormwater distribution systems. The first one is open space irrigation systems. The other one is non-potable distribution systems. Some key points are underscored in terms of designing an appropriate distribution system: "Consideration of customer requirements; Adjusting design criteria; Selecting design peak factors; Methods for peak leveling; Controlling distribution non-potable water; Minimization of bacterial and algal build up; Corrosion risk and so forth"

Stormwater Practices Effective stormwater practices are integrated into the urban landscape to improve their function and performance. Twelve principles that help define the successful integration of a stormwater practice in the landscape include.

Twelve Principles 1.

Provides Reliable Pollutant Removal Performance.

-The practice should be sized so that it captures sufficient volume of runoff and employs a sequence of pollutant removal mechanisms via a treatment train approach to maximize the removal of key pollutants of concern.

2. Mimics Pre-development Hydrology.

-The practice should operate in a manner so as to replicate pre-development hydrology for a range of storm events such that it safely recharges groundwater, protects downstream channels and reduces off-site flood damage.

Twelve Principles 3. Integrates the Practice into Overall Site Design.

- The overall design of the site should support the function and performance of the practice, by minimizing or disconnecting impervious cover, implementing source controls, and utilizing better site design practices that reduce the quantity and adverse quality effects of runoff generated by the site.

4. Has a Sustainable Maintenance Burden - Both routine and long–term maintenance tasks should be carefully considered throughout the design process to reduce life cycle maintenance costs and promote longevity of the practice.

Twelve Principles 5. Is Accepted by the Public - The practice should be viewed as an attractive community amenity by adjacent residents or business owners, as measured by interviews, surveys, testimonials, increased property values and other yardsticks.

6. Creates Attractive Landscape Features.

- The practice should be an integrated practice designed to be highly visible within the site and serve as an attractive and inviting landscape feature.

Twelve Principles 7. Confers Multiple Community Benefits.

- An integrated practice should also contribute to other community benefits such as promoting neighborhood revitalization, expanding recreational opportunities, and educating residents about stormwater.

8. Creatively Uses Vegetation.

- An integrated practice not only greens up the site, but also uses vegetation to effectively promote cooling, shading, screening, habitat and enhanced pollutant removal functions. The design should also explicitly consider how vegetation will be managed over time to maintain functions and minimize maintenance costs.

Twelve Principles 9. Provides a Model for Future Improvement.

- An integrated practice is inspected, evaluated, or monitored so that lessons can be learned to improve the performance and integrate future designs.

10. Realizes Additional Environmental Benefits.

- The design of an integrated practice maximizes other environmental benefits at the site, such as the creation of aquatic or terrestrial habitat, protection of existing natural areas, reduction of urban heat island effects and other urban amenities.

Twelve Principles 11. Reduces Infrastructure Costs.

- An integrated practice reduces the amount of paving, curbs, storm drain pipes and other infrastructure that would have otherwise been employed in a traditional stormwater practice design within the community.

12. Acceptable Life Cycle Costs.

- An integrated practice will not result in high life cycle costs over its useful life.

EFFECTS OF POOR STORMWATER MANAGEMENT • • • • • • •

DOWMSTREAM FLOODING STREAM BANK EROSION INCREASED TURBIDITY FROM EROSION HABITAT DESTRUCTION COMBINED SEWER OVERFLOWS INFRASTRUCTURE DAMAGE CONTAMINATED STREAMS, RIVERS, AND COASTAL WATER

TWO MAIN ISSUES OF STORMWATER: 1. RELATED TO THE VOLUMES AND TIMING OF RUNOFF WATER (FLOOD CONTROL AND WATER SUPPLIES) 2. RELATED TO POTENTIAL CONTAMINANTS THAT THE WATER IS CARRYING

ADVANTAGES ➢ Provides proper drainage of surface run-off and avoids damages on infrastructure such as private properties and streets. ➢ Provides possibility to recharge groundwater and reuse precipitation water and surface run-off as irrigation or household water. ➢ Minimizing health risks. ➢ Provides effective stormwater flood control. ➢ Can be integrated into urban landscape and provide green and recreational areas.

DISADVANTAGES ➢ Expert planning, implementation, operation and maintenance required for a stormwater management. ➢ It depends on the technique, a lot of operation and labor required. ➢ There is risk of clogging infiltration system caused by high sedimentation rates. ➢ Temporary covering methods, such as plastic sheeting, can become torn or ripped, exposing the contaminant to precipitation and/or storm water run-off.

Water Management Challenges in the Philippines.

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Fragmentation of water agencies (more than 30 agencies) Lack of science-based data and information for effective planning and decision making 3. Depletion of water availability and quality 4. Rapid urbanization and industrialization 5. Indiscriminate land use and development 6. Increasing volume of solid wastes, pollutants and hazardous wastes 7. Unabated extraction of groundwater 8. Inadequate Sewerage and Sanitation facilities 9. Watershed degradation 10. Inadequate water infrastructure facilities

STORMWATER MANAGEMENT IN THE PHILIPPINES •

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There is no National Policy on Stormwater Management in the Philippines.

However, large corporations and industries have implemented rainwater and stormwater harvesting systems to augment their water supply. The eco-efficient management of their water supply is in line with the companies ISO14001 Environmental Management System which most of them want to achieve as part of their corporate social responsibility.

There is a pilot stormwater and wastewater management project that is being implemented in Cebu. The project aims to strengthen the capabilities of local government officials or the integrated planning and management of rainwater and stormwater recycling and to establish a model for integrated rainwater and stormwater recycling in selected building so as to demonstrate the eco-efficient approaches for water infrastructure. The project aims to promotes awareness and advocacy on eco-efficient water infrastructure development in the Philippines.

REFERENCES: ▪ ▪ ▪

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https://aseaniwrm.water.gov.my/iwrm-in-philippines/ https://www.integratedstormwater.eu/toolbox/ism/strategic-approach?fbclid=IwAR1tcJyjIvb4WfdfOUrcok2jYFjOPz3hZ-DL0kQMtGO8aFXR5ABGHXtFzA https://www.slideshare.net/Doreen118/stormwater-management-ppt55638544?fbclid=IwAR2eFfjIxaOP0ab87x08fOYSeeBQuJjCwM0l00q_eqVMLIxUYmkLW8ItekY http://www.greenvillesoilandwater.com/what-is-stormwater/ https://stormwater.pca.state.mn.us/index.php/Integrated_stormwater_management?fbclid=I wAR1ZJywPfC-nw3ybqFreK-ac0YCB8g2lyXK8hDN-HlQrOASOh4DL42ISlzk https://en.wikipedia.org/wiki/Stormwater_harvesting?fbclid=IwAR0ymPGC7ZwZet0I82c0Wse 3QfxPj1rdcE458kAO992PL2yyFFplvUUcLz0