Drainage maintenance for flood-control infrastructure
Dezu Corporation is a drainage maintenance contractor for flood-control infrastructure in the Philippines. We take on the corrective end of desilting and declogging — main drainage lines, trunk lines, box culverts, pumping station wet wells, and dam drainage galleries where compacted silt and hardened deposits have stopped routine methods — with industrial waterjet pumps, cutting tools matched to the measured pipe, and continuous debris extraction. Nationwide, for national agencies, LGUs, water districts, dam and hydro operators, and airport and estate facility managers.
Why restore blocked drainage before building new capacity?
Every drainage network was designed on the assumption that its lines flow at full bore. A main drainage line half-filled with compacted silt, or a box culvert with hardened deposits across the invert, passes a fraction of its design flow, and any new capacity built upstream discharges into that same restriction. Corrective restoration returns the capacity the system already paid for, on a cleaning program's timeline rather than a construction program's. That is the engineering case for putting desilting and declogging of the existing mains first. It is also why a cleared line has to stay cleared. A line that was only holed through blocks again. The full argument is in our guide why drainage still floods after declogging.
Which flood-control drainage assets does Dezu serve?
Dezu fields the pump classes, tooling, and method for the drainage assets flood-control systems depend on. Delivered proof is further down this page; this is the capability map.
Main drainage lines and trunk lines
Desilting and declogging of large-diameter mains and storm trunk lines — compacted silt and hardened deposits cut from the wall, conveyed to the access point, and extracted continuously, restoring the line toward its design bore.
Box culverts
Box culvert desilting and declogging, including fully blocked cells — rotary unpluggers open the pilot path, cutting heads sized to the measured bore take the deposit to the wall.
Pumping stations
Wet wells, intakes, and forebays cleared of the silt and debris that starve the pumps — scoped and scheduled around station operation.
Drainage inlets and laterals
Inlets and connecting laterals cleared as part of a mains program, so restored trunk capacity is actually reachable from the surface.
Dam drainage galleries and foundation drains
Foundation drain holes and gallery drains cleaned to the owner's dam-safety requirements — controlled pressure and flow, no packers so pressure cannot build against the structure, undersized cleaning heads, before-and-after flow measurement.
Airport and estate storm drainage
Terminal and industrial-estate storm drainage restored correctively — the 2022 airport terminal drainage restoration is the delivered anchor for this class.
Why is a combination sewer truck sometimes not enough?
A combination sewer-cleaning unit, the jetvac (in the Philippines often called a combi truck, vacuum truck, or siphoning truck), is a genuine engineering achievement: jetting pump, vacuum blower, debris body, and water tank on one chassis. The trade-off is built in. Every component is sized inside one truck's weight and power budget, and one machine divides itself between putting water in the line and taking debris out of it. Published specifications for representative combination units put the water end at roughly 2,000 to 3,000 psi at 55 to 120 gpm. That is the right water end for flushing silt and organics down a line, and a different pressure class from the 10,000 to 20,000 psi range used to cut hardened scale and compacted deposits.
Industry guidance draws a similar line. NASSCO's technical publications on heavy and large-diameter cleaning (Tech Tips editions of 2012 and 2015) put it at about 30 inches (about 760 mm). Below that, a combination vacuum-and-jetting truck is usually the right machine. Above it, debris is measured by the ton, deposits turn compact and difficult to jet, and cleaning shifts to dedicated vacuum, pumping, and mechanical systems with continuous extraction. Hardened and compacted deposits are their own work class — the standard cleaning specification itself anticipates cases that defeat the tools normally used in the industry. That guidance is written for large-diameter sewers and interceptors; Philippine flood-control mains, trunk lines, and box culverts carry the same deposit physics at the same diameters.
So the honest sorting rule is simple. For routine maintenance of smaller drainage lines — silt, organics, light debris in lines up to roughly 30 inches — the jetvac is the right machine and the right economics: one crew, one mobilization, purpose-built for exactly that duty. Dezu does not compete with that work and does not claim to beat it. Dezu's lane is the corrective end, the lines the combination class was sent to and could not clear. If a jetvac can clear your line, use the jetvac; when it cannot, that is the work Dezu is built for.
How does Dezu's two-machine method work?
Dezu runs the two halves of drainage cleaning as two dedicated machines. A standalone industrial jetting unit, sized for the cutting tool rather than for a shared chassis, cuts scale and compacted debris and conveys it toward the access point. A dedicated vacuum unit works the access point continuously, so extraction never waits for jetting and jetting never waits for extraction. Each machine at full capacity, at the same time.
The jetting side is Dezu's fleet of NLB 225-series industrial pump systems with convertible fluid ends. Manufacturer-rated configurations of the same power frame run from 8,000 psi at 49 gpm to 20,000 psi at 23 gpm, with higher pressure classes above that, and the pressure and flow point is configured to the deposit — high flow for conveying loose material, high pressure for cutting hardened scale.
The cutting head is selected to the measured pipe, not the nominal size. Rotary unpluggers open fully blocked lines, self-rotating cutting heads take scale off the wall, and large-pipe rotary heads with centralizers and extension arms cover lines up to roughly 37 inches (about 940 mm) of measured clear bore. Dezu is StoneAge's Authorized Distributor — Philippines and runs the same tooling it sells. The pump fleet and tool families are on the equipment page; the full comparison with combination units is in the guide jetvac vs hydro jetting for drainage declogging.
What drainage and hard-deposit work has Dezu delivered?
The deposits that block flood-control drainage — hardened scale, compacted silt, construction debris — are the deposits Dezu removes for a living. The delivered drainage engagement below is the 2022 airport terminal restoration, delivered under Dezu's hydro jetting service. The industrial engagements beside it are the same deposit physics delivered at industrial pressure classes, shown as method proof, not as flood-control work.
Hydro Jetting — Airport Terminal Drainage Restoration (2022)
Fully clogged drainage affecting a VIP area cleared by hydro jetting. As of 2026, never called back for the same problem. Read the full case study.
Reactor Tank Descaling for Plant Decommissioning — HPAL Nickel Processing Plant (2026)
Five months (January–May 2026) removing mixed sulfide scale from a brick-lined reactor tank with hydro demolition equipment; working volume and baffle plates restored.
Shutdown Cleaning Program — HPAL Nickel Refinery (2023–2026)
High pressure cleaning at every minor (March) and major (September) shutdown since the 2023 major shutdown — six shutdowns delivered to date, retained because Dezu removed buildup others could not.
Pipe Internals Cleaning — Geothermal Facility (2020)
Internal cleaning of geothermal pipework, documented with before-and-after bore photos. Full register at projects.
Clients on delivered work stay unnamed in public copy out of respect for their confidentiality. Full project records and references are available in a meeting.
Who does main drainage declogging for flood-control infrastructure in the Philippines?
Routine desilting and declogging of public drainage is largely carried out by government maintenance crews and their service contractors, and for smaller lines that is the right arrangement. Dezu Corporation serves the corrective end as a drainage maintenance contractor for flood-control infrastructure: main drainage lines, trunk lines, box culverts, and pumping station wet wells where compacted silt or hardened deposits have stopped routine methods. Dezu holds PCAB Contractor's License No. 56253, is a PhilGEPS Platinum Member, and serves public and private infrastructure operators nationwide.
Can hydro jetting clear a fully blocked box culvert?
Yes, when the water end and the tooling are sized for it. A fully blocked line is opened with a rotary unplugger head that cuts a pilot path through the obstruction, then taken to the wall with cutting heads matched to the measured clear bore. Large-pipe rotary heads with centralizers and extension arms cover lines up to roughly 37 inches (about 940 mm) of measured clear bore. Dezu cleared a fully clogged airport terminal drainage line by hydro jetting in 2022 and, as of 2026, has never been called back for the same problem. Access, flow management, and continuous debris extraction are planned per culvert before the first pass.
Should you hire a jetvac combination truck or standalone hydro jetting?
If a jetvac can clear your line, use the jetvac. For routine desilting and declogging of drainage lines up to roughly 30 inches (about 760 mm), a combination sewer-cleaning unit is the right machine and the right economics. When the deposit has hardened or compacted beyond what its sewer-flushing water end can cut, or the line is larger and the debris volume calls for continuous extraction, that is the work Dezu is built for: a standalone industrial jetting unit and a dedicated vacuum unit, each running continuously at full capacity.
The full comparison, including where each option wins, is in the guide jetvac vs hydro jetting for drainage declogging.
Can dam drainage gallery foundation drains be cleaned by high pressure water jetting?
Yes, within controls that dam-safety practice has already documented. The reference evaluation, US Bureau of Reclamation report DSO-98-16 (1999), documents a 15-drain program cleaned by water jetting at 12,500 psi and 15 gpm under three controls: no packers, so pressure cannot build against the structure; a cleaning head sized well under the drain-hole diameter; and before-and-after flow measurement as the acceptance test. Dezu's manufacturer-rated pump configurations and rotary tooling cover that envelope, and every gallery scope is engineered to the owner's dam-safety requirements before mobilization.
A blocked main, culvert, or gallery on your network?
Send the asset type, the measured or nominal size, the length between access points, and what the last cleaning attempt found. We reply with a method recommendation and a scope-based quotation.