Depok plans a 1,000 tonne RDF plant on a landfill already holding 2.9 million tonnes

Two routes out of one constrained site

Depok's environment and sanitation agency is preparing a refuse derived fuel plant at TPA Cipayung, designed to process 1,000 tonnes of waste a day. Reni Siti Nuraeni, who heads the agency, set out the plan following an inspection of the site.

The plant is one of two routes the city is pursuing. The second is an agglomeration arrangement with Bogor regency, under which waste would be handled at a facility in the Kayumanis area with a capacity of around 1,000 tonnes a day, of which roughly 700 tonnes a day would come from Depok.

Together the two routes would account for a volume well above what the site currently receives. TPA Cipayung takes between 900 and 1,300 tonnes a day, and the accumulated material at the site has reached roughly 2.9 million tonnes.

The RDF proposal is progressing through the Depok council for approval, and the funding structure envisaged involves a third party or a private business entity rather than the municipal budget alone.

The number that changes the problem

The figure worth pausing on is 2.9 million tonnes.

Daily inflow figures describe a flow problem, and a flow problem can be solved with capacity. A stock of 2.9 million tonnes is a different kind of problem. It does not decline because new capacity is built. It sits there, generating methane, occupying land that Depok does not have to spare, and carrying the fire risk that materialised at this very site earlier in the year.

The distinction matters for how a facility is specified.

A plant sized against daily arrivals stops the mountain growing. Reducing the mountain requires capacity above the inflow, or a landfill mining operation feeding the same line.

Either route is a deliberate choice that has to be written into the specification and the contract. Neither happens because a facility exists.

An RDF plant at 1,000 tonnes a day against arrivals of 900 to 1,300 sits roughly at the level of the inflow. Combined with 700 tonnes a day routed to Kayumanis, the arithmetic implies real headroom, which is what would allow the accumulated material to be worked down rather than merely capped. Whether that headroom is actually directed at the stockpile is a design and contracting decision rather than an automatic consequence.

Why Depok has to build up rather than out

Depok's constraint is land, and it is absolute rather than financial. The city cannot expand its disposal area, which removes the option most municipalities reach for first when a landfill fills.

That constraint explains both elements of the strategy. A processing plant placed on the existing site converts a land problem into a technology problem, because the same footprint handles more material. An agglomeration agreement with a neighbouring regency converts it into a logistics and intergovernmental problem, because the material travels to where capacity exists.

Both are harder to arrange than acquiring more land, and both are where a growing number of Indonesian cities now find themselves. Depok is not unusual in this. It is early.

The agglomeration route deserves particular attention. A city sending 700 tonnes a day into another jurisdiction's facility depends on an agreement that has to survive changes of administration on both sides, and on a commercial arrangement that gives the host something durable in return. Those agreements are the connective tissue of regional waste management and they are still rare.

The agency is also upgrading heavy equipment at Cipayung, which sounds routine and is not. Operating a site safely during a transition, with compaction and cover maintained while a processing facility is built alongside, depends on machinery that works.

There is a feedstock quality consideration attached to the RDF choice as well. Refuse derived fuel is judged on calorific value and moisture content, and both deteriorate when wet organic material enters the processing line. A city feeding an RDF plant with mixed waste produces a low grade fuel that is difficult to sell, while a city that diverts its organic fraction first produces a product industry wants. Depok's separation programme is not, in other words, an activity separate from the plant. It is what determines whether the plant is economically viable.

What ending open dumping means here

Depok has stated an intention to end open dumping at Cipayung, in line with the national position. That is the commitment the RDF plant and the Bogor agreement are ultimately there to serve.

The sequencing challenge is familiar from other cities this year. A site cannot stop accepting mixed waste until there is somewhere for the diverted material to go. The RDF plant is in council approval, and the Kayumanis arrangement depends on a neighbouring jurisdiction. Neither is available tomorrow. Meanwhile arrivals continue at up to 1,300 tonnes a day.

The practical implication is that the interim period is where the risk sits, and interim measures, source separation, organic diversion and improved daily operation at the site, carry the transition until the facilities arrive.

Sirkularium's view for government and public institutions

Three observations.

First, on specifying against stock as well as flow. Any city with a large accumulated stockpile should state, when it procures a processing facility, whether the design capacity is intended to stabilise arrivals or to draw down the stock. Those imply different capacities and different contract terms. We would encourage Depok to publish which of the two the 1,000 tonne figure represents, because it determines whether the 2.9 million tonnes has a route out or simply stops growing.

Second, on agglomeration agreements as infrastructure. The Kayumanis arrangement is as important as the plant and receives a fraction of the attention. Cities entering these agreements should seek multi year terms, a defined tariff, a dispute mechanism and clarity on what happens if the host jurisdiction's own volumes rise. Provinces are well placed to broker and underwrite these agreements, and doing so would unlock capacity sharing that individual cities struggle to arrange bilaterally.

Third, on the interim. Between council approval and commissioning there is a period of at least a year in which Cipayung continues to receive waste at close to its current rate. Depok's upstream programmes are what carry that period. Districts in the same position should resource source separation during the construction window rather than treating it as something to begin once the plant opens.

What to watch next: council approval for the RDF plant and the financing structure that accompanies it, the terms of the Kayumanis agglomeration agreement, whether the plant specification addresses the accumulated stockpile, and whether daily arrivals at Cipayung begin to fall before the facility is commissioned.

Depok has two routes drawn and a stockpile that will not wait. Sirkularium will continue following which arrives first.