Posted by: rainworks | September 7, 2009

Rainwater Porous Roads and Paths

 A service road and Golf Cart path on a Caribbean island

With an average of 126 inches of annual rain that runs through in the low areas, construction proved to be a simpler process than the prior road design which required hundreds of truckloads of stone and many pieces of heavy equipment. GeoWeb and GeoTextile products were selected to enable a porous road surface over highly organic wet areas, and over tree roots. This allowed the natural flow of rain water to follow its natural path to the Mangroves and Caribbean Sea, and while continually nourishing the jungle growth.

Starting laying the GeoWeb Service Road

Starting laying the GeoWeb Service Road

After a rough base of river stone and gravel was put down, (allowing water movement laterally under the road surface) compacted by hand and smoothed, a GeoTextile membrane was applied to the base surface. The GeoTextile allows some water seepage but does not allow earth (mud) from pumping up to the road surface, or roots from entering up into the road surface. Then as shown in the photo; sections of GeoWeb were stretched outward from both sides with wood stakes and red nylon cord. A continuous side perforated GeoWeb base was created by attaching GeoWeb sections with heavy duty Nylon ties.

Temporary drainage while filling GeoWeb

Temporary drainage while filling GeoWeb

Temporary drainage was dug to assist construction during the rainy seasons.  A crushed stone aggregate was then loaded onto the GeoWeb surface and raked into the GeoWeb cells forming a reliable surface for the Bobcat front loader to quickly deposit more aggregate. The right center of the (r) photo shows the GeoWeb bundles as shipped, and prior to stretching and attaching.

Still into day one, progress moves along. After the two day construction was complete, the 192m service roadway was compacted with a walk behind power roller and finished to a smooth surface.

Continued progress of Service Road GeoWeb construction

Continued progress of Service Road GeoWeb construction

 

 

After the GeoWeb Porous road still holds no water
After 4 years the GeoWeb Porous road still holds no water

Four years after completion the Service Road/Golf Cart Road still holds no water due to its porous design. This rain forested Jungle road was designed with minimal excavation and with a huge reduction in heavy aggregate and heavy equipment. Where necessary, the first 3km of the rough grade/base required earth retention/revetment walls which were made with terraced GeoWeb, and pillow bases for the culverts were also made utilizing GeoWeb.

A porous foot path from the waterfront up to the Island’s B&B.

Typically the indigenous Indians inhabiting the island wear no shoes and simply trod along on mud trails much like the game trails of North America. However, as an international tourist destination the project required suitable paths for those wearing sneakers, sandals, and especially flip flops. Climbing 90 feet up the hill, a porous road design was used, and because of the wet soil and Rainwater sheding conditions, a semi ridgid design was required.

GeoBlock laid on base of course aggreate 
A preview of what a section of GeoBlock looks like 

GeoBlock laid on a base of course aggreate, and a  preview of what a section of GeoBlock looks like.

First a GeoTextile membrane was placed on the base surface. Then a 1 inch crushed aggregate was placed on the GeoWeb to assist lateral drainage. The 1 x 0.5 meter sections of GeoBlock were then placed on the aggregate with the interlocking tabs screwed together with 1 inch #12 Pan Head stainless steel sheet metal screws. 

Start of pea gravel fill of GeoBlock path 

After the 2 inch deep GeoBlock base mat was laid and adjusted, it was filled with pea gravel. The major rise in the center of the path was completed by building a series of steps with 1’ x 1’ x 4” Landscape webbed concrete blocks, these also were filled with pea gravel, and several 10’ long 5-8 degree slopes were also added. This path was created with tourists in mind, especially the potential retired crowd with luggage and or canes. Therefore each step rise was limited to 4 inches, and minimum tread length of 14 inches at center was used.

A view from the top of what was a trecherous climb 

A view from the top of what was a trecherous climb, my path construction supervisor shows off his handiwork.

Stormwater Runoff and the District of Columbia

Impervious concrete surfaces cover 65% of District land, equaling an area big enough to hold 175 Washington D.C. National Malls!

Stormwater runoff is Rainwater that flows off impervious surfaces such as rooftops, driveways, roads, sidewalks and sometimes even lawns. Stormwater runoff travels from these surfaces to our streams, picking up pollutants such as oil and grease from our roadways and driveways as it goes. Nutrients from lawn fertilizers and bacteria from pet waste may also be picked up by Stormwater and carried to our streams.

All sidewalks should be of brick where they are easily removable and replaceable, if not much more beautiful. Presently the water authority yanks out the bricks and replaces them with a large Black Asphalt patch when reconnecting water connections to the homes.

It’s obvious that a brick sidewalk adjusts more smoothly than do concrete slab sidewalks which break up from tree root growth, and can cause more hazardous areas for walking, wheel chairs, and baby carriages.

Brick walkways can be done with shovel ready local hand labor instead of high “carbon foot print” heavy equipment.

Although it should be noted that when using new perfectly cut style brick, one eighth to one quarter inch joints should be allowed for a better porous integrity.

However, Washington D.C does offer a solution

for home owners by promoting a commercial solution; Pervious Paver concrete type designer pavers.

Pervious pavers permit water to seep around and through their paved surface, and soak naturally into the ground underneath. In short, pervious pavers are a self-draining system.

Aesthetically pleasing pervious pavers are commonly used for patios, walkways, driveways, and landscaping. Pervious pavers also come with a lifelong guarantee in materials and labor cost.

Replace impervious surfaces with pervious pavers, and have $1200 of the cost difference covered. All RiverSmart Homes practices require co-payments for landscaping that reduces Stormwater runoff to help the District’s streams and rivers.

Find more information about RiverSmart Homes and Pervious Pavers at:

http://ddoe.dc.gov/ddoe/cwp/view,a,1209,q,497794.asp or call 202-535-2252

DC’s other green initiatives also include Rainwater Harvesting and Sustainable Green Roofs

Regency House Green Roof
The 6,140 square foot sustainable roof of the Regency House Senior Center consists of low-level vegetation, stone walkways, and assorted seating areas. A rain-harvesting system helps irrigate the roof using rainwater as much as possible instead of the city’s water. In addition, the roof includes six state-of-the-art solar panels that collect energy used to power the building.

A recent TV program also showed the many Rainwater Harvesting systems in use in D.C. which included thousand gallons large cisterns.

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Responses

  1. Thank you! My family owns land in Jamaica, and my biggest concern was what the grounds would be like after heavy rains. I saw this product featured on TV but couldn’t remember the name. Right now the roads break apart after heavy rains and they take forever to repair them. This system looks like it would last a long time.


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