Stormwater Commission

IF we are to do it via cartoon physics, we can just scoop dense patches of urban communities, mold them like high-rise sandcastles and then run a finger to create stretches of swales on empty spaces, you’ll have a city safe from storm water flooding. Too bad the world wasn’t designed by Cartoon Network.

Januar Yap

Meanwhile

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The recent jest emerging from the Metro Manila flooding was that designing the future house will have to be a collaborative effort that’ll involve a naval architect. The joke comes with an illustration of a house with a scuba diver exiting via the basement.

Funny, except that as they appear, storms come like persistent visitors with really rude manners.

I take my hats off the Malaysian government for its foresight and political will. In the last few decades since its independence, it saw a shift from its agricultural economy to an industrial one, and thus anticipated a growing percentage of its populace in urban areas. In the ‘70s, only 26.8 percent of its populace were urban dwellers, but in 1991, the country saw half of its populace living in the cities. It projected that in 2020, 65 percent will be in the urban areas.

Seeing more paved areas as the cities expand, government saw a decreasing permeability of its land surfaces, exposing the city to more storm water flooding.

What did the Malaysian Government do? Its Department of Irrigation and Drainage re-crafted its then 25-year-old “Planning and Design Procedure No. 1: Urban Drainage Standard and Procedure for Malaysia” into the much more relevant and advanced “Urban Stormwater Management Manual for Malaysia” (MSMA).

They found that the traditional approach of “rapid disposal” only worsened the flooding since it merely deposited sediments and pollutants on bodies of water and, therefore, reduced their water-conveyance capacities.

In Cebu, you can imagine what a rapid disposal of storm water, corrupted by urban pollutants, would do to our surrounding seas. You can imagine our rivers spewing black ink like a squid into our poor seawaters. You don’t want your friendly butandings walking, er, swimming away because you play dirty. Is there a night-vision underwater goggles? So, maybe, we need a paradigm shift.

Anyway, what I find interesting in Malaysia’s MSMA is that it looks at stormwater not as a disturbance, but as an opportunity to contain an added resource. The new guidelines specified more stringent requirements for developers to comply with.

The measures intend to control the quantity and quality of the runoff by creating swales, sub-surface modules, dry ponds, detention ponds, wetland and wading streams and gross pollutant traps. This was to “retard the flow” and re-channel stormwater into areas for reuse. The trick here is to set free the water in catchments in its purified form and thus not damaging the environment.

The MSMA requires land developers to fill in a long checklist of requirements. One of those is that a developer needs to submit an erosion and sedimentation control plan. The guidelines set very specific gauges on holding capacities of a catchment for a specific amount of rainfall for a number of days. A sediment trap must also have the capacity to retain 70 percent of coarse sediment.

I don’t know if we have that kind of requirement in our own backyard, but last I remember, a bunch of residents stormed up a developer because the project gushed forth streams of mud into their houses after incessant rain. The MSMA guideline also specified “aesthetics,” so that developers would have to find a way that their catchment areas are by themselves livable sites and not look like grotesque killing fields.

Cebu City should begin looking at proven and tested best practices on stormwater management. The nursery song about driving the rain away is passé. Consider rainwater as a resource, heaven-sent.