Grade is a site fact
Before anyone argues about unit sizes, walk the plot with a level and a tape. The island’s coastal terraces are coral limestone, and terraced ground tends to arrive in steps rather than in one continuous plane, so two plots a short distance apart can hand you very different problems. One may need nothing more than a shallow crossfall to a soakaway. The next may need a low retaining course, a landing and a run of shallow risers. Measure what is there rather than working from a plan drawn before clearance.
What to establish first
Slope work goes wrong at the survey stage far more often than at the laying stage. Fix all of this before anything is ordered:
- Finished floor levels at every door, gate and pool edge the paving has to meet.
- Where water goes once it leaves the surface, and what it crosses on the way.
- Whether the ground under the build-up is compacted fill, weathered rock or something softer under a thin cap.
- Turning and parking positions, because those change the depth you need.
- What the existing building fabric actually is, since that governs tone and texture more than any product page.
Why small units follow a fall
A sett is a small block, and a small block can be tapped down a few millimeters without opening a lipped edge against its neighbor. Across a run of falling ground a sett course absorbs the change gradually, joint by joint. A large format slab cannot do that. It either sits proud at one corner or asks for a wedge of bedding underneath that will move under load. On stepped or irregular ground the small unit is the practical answer rather than the decorative one, and that is the whole case for cobblestone setts graded for slopes on this kind of site.
Bedding and jointing where rain is scarce
Bonaire is semi-arid. Annual rainfall runs roughly 350 to 450 mm, about 14 to 18 inches, with a rainy season from October to January and the wettest weather in November and December. That pattern is harder on a slope than steady year-round rain, because the surface spends most of the year dry and dusty and then takes its water in concentrated spells.
- Design the joint for infiltration where the ground below can accept it, rather than for a sealed skin.
- Keep a compacted, well graded sub-base under the laying course, because thin bedding over loose fill will rut.
- Never use beach sand as bedding or jointing material, since taking sand from the shore is an offense here and the material is salt loaded in any case.
- Detail a defined overflow route for the spells that exceed what the joints can take.
The park boundary is the high-water mark
Bonaire National Marine Park covers all the water around Bonaire and Klein Bonaire, from the high-water mark down to 60 m depth, and STINAPA Bonaire manages it under the marine environment ordinance. On a shoreline plot that boundary is not somewhere offshore. It is at the bottom of the slope you are paving, which means silt leaving the works is heading straight for protected water.
- Stage excavation so that bare graded ground is never left open through a rainy-season spell.
- Use silt barriers and a settlement point at the low end of the site.
- Keep cutting slurry and tool washings away from any route that drains toward the shore.
- Check whether the works touch the coastal zone, where some activities need permission from the Bestuurscollege.
Wind, salt and the face you specify
The north-east trade wind here is close to constant, averaging around 7 m/s, which is about 25 km/h or 15 mph. It carries salt onto every exposed face, and with so little rain to rinse surfaces down the dominant decay mechanism is salt crystallization rather than freeze-thaw. Specify low-porosity, low-absorption units in splash and windward positions, and ask for absorption figures rather than a description. Lighter tones also stay more comfortable underfoot under high sun. Where a slope faces the wind directly, format and depth deserve more thought than tone, and the Bonaire stone hub sets out the options.
Depths, restraint and step transitions
Once levels and drainage are settled, the remaining decisions are structural rather than aesthetic.
- Deeper units where vehicles cross or turn, with the same format at a shallower depth acceptable on a path.
- Positive edge restraint at every downhill margin, cast or bedded, not a soldier course relying on friction.
- Risers formed from full units rather than cut slivers, so nothing works loose at the nose of a step.
- A consistent joint width up and down the fall, because a joint that opens on the slope reads as a fault line.
How the pallets arrive
Bonaire is a special municipality of the Netherlands and it uses the US dollar, official since 1 January 2011, so a US supplier can quote in dollars with no conversion in the middle. Ocean freight runs direct from Florida: a weekly ABC service leaves Port Everglades on Saturday and reaches Kralendijk on Thursday, a five-day sailing, with the container staying on the same vessel the whole way. The Port of Kralendijk operates around the clock and has a container terminal with handling equipment and warehousing. There is no import duty, the rate is set at nil for all goods, and the operative levy is ABB at 8% on the import of goods, charged on the customs value of the goods plus insurance plus transport, declared to Douane Caribisch Nederland. Plan the levels first and the slope stops being the difficult part of the job.