A View Of The Manila Beach Sand Nourishment Without The Emotions

The old world charm of Manila Baywalk area. In early 1900s, development had already pushed right to the sea. There is not much of beach width as can be see in this heritage photo.  What is obvious is the cleanliness of the beach front back then.

Modern day Manila and pollution is a big problem throughout the city, especially in the waterways. Major rivers Pampanga, Pasig, Talisay, Meycauayan, Navotas-Malabon-Tullahan-Tenejeros, and Maragondon, and the city pour floatsam, untreated waste water and sewage into the Manila Bay. The garbage is an eyesore, but what cannot be seen in the water is terrifying. The e-coliform level has reached as much as 330 million mpn/100ml, which is 3.3 million per cent over the acceptable health standard.

After a massive beach cleanup, Manila Beach is a sight to behold, even without white sand. However one's political stand, the beach clean up is a helluva of a Herculean task and ought to be applauded. All previous administrations have talked about it, but unable to do anything.

Manila beach after the Php389m beach nourishment. This covers a stretch of about 500m in the locality of the US Embassy. This beach nourishment project came out of the blue and, by the country's standard, very quickly completed. The sand came from a dolomite mining plant in another island (Cebu). It was excavated, crushed to sand, and shipped to Manila. Despite the Covid-19 pandemic, Filipinos came to check out their new pride.

The white sands of Manila Beach after the rain and natural waves have had their say. A pyhrric victory for the administration and absolution for detractors who said its a vanity project and money should have been better spent on pandemic assistance to the needy.

Let's leave the politics and emotion aside. Let's try to understand some basics of the science and engineering behind beach nourishment.

The natural beach sand cycle:

Incoming wave is called the swash. It brings with it the sediments from the sea and deposits them on the beach. This process is called accretion. The outgoing wave is called the backwash which carries sand back to the sea. This is the erosion.

Where is the sand coming from? It is from a submerged sand bar which could be kilometres offshore. The volume of sand in the sandbar is a few thousand times more than the sand that is seen on the beach.

Nature crafts a particular beach depending on the gradient of the slope, native sediments, wave energy, longshore drift, current patterns, wind, storms, sea-level changes, and coastal topography. Without any coastal engineering construction, but simply pouring the dolomite sand, it is only a matter of time before nature will return the beach to its previous condition of equilibrium. The added sand will ultimately end up in the sad bar.. The only way the Manila beach can be widened is to pour billions of tons of dolomite sand onto the sand bar. This is of course humanly impossible.|

The engineering considered:

Geotube perimeter -

DENR have insisted the sand can be retained by the use of Geotubes. The snake-like strings in the "sand washed out" photo appear to be the Geotubes. They are obviously not in position but brought in after the sand has been deposited. A further tell-tale sign is the pathetic use of sandbags. The use of Geotubes seemed like an after-thought for a project lacking engineering approach.

Geotubes are mostly used in protection of dunes and embankment. DENR idea seems to be to use Geotubes as perimenters to cordon in the sand. The seaward portion is likely to be submerged. There don't appear to be any examples of installations like this anywhere else. It is possibly experimental.

The Geotube perimeter will prevent the seaward movement of the sand. At the same time, it also prevents the shoreward movement. In the frothy waters of the swash and surf zones, sand grains are floating in the water. The impact is yet to be seen.

Geotubes are porous. They are filled with the native flurry. Fine sediments flow through it. Submerged Geotubes have a longer lifespan. The portion that is above water line is subject to the wear and tear effect of the waves thus shorter maintenance intervals.

Submerged Geotubes are hazards to boating activities and swimming. However, if these recreational activities are not allowed given the dangerous e-coliform levels in Manila Bay, then it does not present a problem.

Breakwaters -

The Dept of Public Works and Highway announced belatedly that they are considering the construction of breakwaters. This underlies the project was approached without engineering concepts and coordination amongst agencies. It's an afterthought.

Breakwaters may be offshore or onshore. There is already an existing offshore breakwater some kilometres out in that part of the bay. It is obvious DPWH was talking of onshore breakwaters.

Onshore break waters are barriers built parallel to the beach. These contraptions are common and have been proven highly effective in many beaches all over the world. They help to entrap the sand on the backwash and stabilise the beach from erosion.

The onshore breakwaters on the reclaimed land on  Singapore's East Coast Park were constructed in 1982 and there have been no need for beach nourishment for 38 years.

The sand:

This could be onsite or offsite. Onsite sand is predominantly used in beach nourishment for 2 reasons. It is more economical to dredge and pump in the sand from the sand bar offshore. Another reason is ecological. Native sand is preferred.

Manila white sand came from a dolomite mine in Cebu. For a country that has good legislation for extractive industry, the project is in breach of environmental requirements at the production and the deposition sites. There were no environmental studies done at both extraction and dumping sites. Neither were official permits issued. The Cebu mine in fact has breached its mining share agreement with the government and the local governor has suspended the mine's local sales operation.

Why is native, or local sand, preferred? Beach nourishment impacts the ecological system both onshore and offshore. The benthic invertebrates population decrease which affects the fishes and the birds. The impact is greater if offsite sand is used. The Manila Beach nourishment is not large scale, so this may not be a big issue. However, the use of dolomite sand is controversial. Government managers said it poses no dangers to human recreation activities, but biologists warned of the toxicity of dolomite particles. The sudden fish kill in the bay after the beach nourishment was completed is a tell tale sign. Is there a reason no other beach nourishment projects in the world use dolomite sand?

The size and jaggedness of the grains of sand matter. The size affects the way the sand is distributed by the accretions and erosion of the waves. Finer sediments are deposited further upshore and bigger sized end up at the waterline. Offsite sand interrupts the natural composition of native sand and thus the natural equilibrium. The long term outcome is uncertan once nature is disturbed.

The jaggedness of the sand matters. One way beach sand mitigates erosion is it hydraulic stabilisation characteristic. This works by the interlocking effect of the jaggedness of the sands. The finer sands with more rounded shapes have less hydraulic stability and gets washed away easily.

Thus one grain of sand is not the same as another. In the Singapore land reclamation project, supply of sand is subject to quality control in terms of size and jaggedness. It's not a simple case of any sand will do.

It would seem the native sediment at the Manila Bay area is more silt and volcanic in nature. Thus the sand tends to be blackish and very fine. The man-made dolomite sand is coarser and bigger grains. The tidal dynamics will tend to pull the white sands to the water line and the finer black sands deposited higher up the shore. Maintaining white sand there will be a tough job working against nature.

The Mandamus :

Is the sudden and seemingly rushed projet a populist and vanity project? The government maintains it is in abeyance of the 2008 Supreme Court mandamus.

Wikipedia: "Mandamus is a judicial remedy in the form of an order from a court to any government, subordinate court, corporation, or public authority, to do some specific act which that body is obliged under law to do, and which is in the nature of public duty, and in certain cases one of a statutory duty."

In 1999 a group of complainants calling themselves "Concerned Residents of Manila Bay" filed a complaint in the Regional Trial Court in Imus, Cavite against various government agencies for cleanup, rehabilitation, and protection of the Manila Bay. Complainants won. In 2002 the lower court ordered the various agencies to do their respective tasks :

MWSS - sewerage treatment facilities
WUA - proper disposal of waste
DENR - waste facilities to rid the bay of toxic and hazardous substances
PPA - discharge of solid and liquid wastes from docking vessels
MMDA - solid waste and liquid garbage disposal system
DA - marine life in Manila Bay
DBM - budget for rehabilitation of Manila Bay
DPWH -removing debris and garbage in the bay
DOH - fecal sludge and sewage coming from septic tanks
DECS - education on environmental protection
Coast Guard and PNP Maritime Group - prevent illegal fishing in Manila Bay.

The order was sustained by the Court of Appeal in 2005. The case went to the High Court which upheld the decision. It issued the Mandumus in 2008, penned by Justice Velasco. The Mandamus set out the tasks of each agency with quarterly progress reports. A Mandamus remains open until all ordered tasks have been completed.

Read the Mandaus here

Three cheers to the Caviteans.

It is a bit far-fetched that the administration can be compelled by a Mandamus which had been swept under the carpet for 12 years. In the scheme of things for the rehabilitation of Manila Bay, the beach nourishment ought to be the final tasks after all the other systems are in place to control sewerage, solid, liquid and garbage disposal and the rivers are rejuvenated. It's a case of trying to run before one learns to walk.

Manila Bay Coastal Strategy :

It is naive to believe such a complex project for the rehabilitation of Manila Bay can be organised and supervised by the courts. The tragedy is that the Philippines already has a comprehensive coastal strategy for Manila Bay and nobody is paying attention to it.

Partnerships in Environmental Management for the Seas of East Asia (PEMSEA) is a regional partnership programme implemented by the United Nations Development Programme (UNDP) and executed by the United Nations Office for Project Services (UNOPS). Its mission is to foster and sustain healthy and resilient coasts and oceans, communities and economies across the Seas of East Asia through integrated management solutions and partnerships. PEMSEA regional development office is in fact, hosted by Philippines with its office within DENR in Quezon City.

In 2001 PEMSEA completed the Manila Bay Coastal Strategy. It provides a comprehensive environmental management framework, targeted outcomes and a series of actions programs involving the participation of both government and non-government sectors to bring back the old glory of the Bay. A PEMSEA project has logistical. funding, and technical expertise support from various international partnership agencies within the UN and other countries.

It's a crying shame the Manila Bay white sand project was rushed through with no proper environmental studies nor engineering modelling instead of working through PEMSEA framework for the Manila Bay Coastal Strategy where support may be availed.

For the full 121 page Manila Bay Coastal Strategy read here.

The economics :

2,000 to 3,000 beach nourishment projects are carried out annually all over the world. These projects are expensive and they are not one off events. The sand replenishment is repeated after an interval of a few years, the periodic cycle differs from site to site. Most beach nourishment projects are conducted because the onshore  economic activities generate positive payoffs. This may not be so for Manila Bay. However, it does not preclude the government from expending for the purpose of providing recreation facilities for the people to enjoy.