HOW THESE PLANS WERE DEVELOPED
The guidebook, 'Unpaved Road Standards for Caribbean and Pacific Islands' is published by the Horsley-Whitten Group. It is endorsed by DPNR and is considered the bible on the subject. The HW Guide provides both very detailed specifications for best practices and general principles for roads just like ours.
A team from HW came to STX to conduct a study of the watersheds of Creque Dam through Prospect Hill/Butler Bay. Our road was one of the primary concerns. They spent several hours over three days with us reviewing the road and our plans.
This link will take you to the guidebook. It has been invaluable over the last year in arriving at the plans we have now.
UNPAVED ROAD PRINCIPLES
HW Guide p4.
Get water off the road quickly to prevent flows from concentrating.
Drainage is the most important factor. Many outlets all along the road are required to direct the water off the road and down the slope towards the gut. The steeper the incline, the more frequent the outlets. This will reduce the volume of water running downhill.
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Maintain proper cross road slope
Most of the road is pitched to an out-slope. Pitch refers to the angle side to side, it either slopes into the hill or out to the gut.
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Maintain surface compaction
The guidebook suggests a 15 ton roller compactor, for the urgent repair plan we will use a 15 ton traxcavator.
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Stabilize ditches
At the lower part of our road the pitch changes from out-slope to in-slope. This requires a ditch along the hillside to convey water all the way down to the bottom.
Check dams are required to slow the velocity of water as it runs downhill. Check dams of rock rip rap, placed at intervals in the ditch, along with variable depths of the ditch create a 'stair step' effect that slows the water down. Water absorbent grasses planted in the ditch can also help.
Disconnect from paved surfaces (in our case that means the coast road)
At present, we are working directly with the HW team for ideas that will stop the water from going out onto the road and into the reef. More to come on this.
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Commit to routine, long term maintenance in order to minimize frequency of grading and major repairs
That's exactly what we are here to do.
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