Let's make a simple comparison of installing a drainage ditch and lining the ditch with Fabriform® vs. other revetment systems (rip rap, articulated concrete block mats, conventional concrete, etc.).
No matter what type of revetment is installed, the ditch will have to be excavated and graded.
The Fabriform® system does not require any additional time for heavy equipment to install. Riprap or precast articulated concrete blocks (ACB's), for instance, will require additional heavy equipment time to place the rock or ACB mats. Fabriform® and ACB's will have anchor trenches that will need to be excavated by smaller equipment like a mini-excavator or trencher.
Fabriform® is shipped via common carrier either on pallets for small orders or loose in box trailers for large orders. RTC Southern's standard panel (roll) size is 3,600 SF that measures approximately 6'x3'x2' when rolled up. This allows for easy handling. Riprap is shipped in multiple loads in dump trucks and ACBs are delivered by semi-trailers, which usually carry only a few mats per load. Conventional concrete is obviously shipped as needed.
Fabriform® panels (rolls) are stored on-site in Connex boxes (storage container) which can hold up to 150,000 SF in a 40' container. Riprap and ACB's have to be stockpiled or delivered as needed in multiple shipments.
RTC Southern's crew size varies depending on many factors. Most installations incorporate a 4 man crew. However, our labor cost for a Fabriform® installation will be lower than ACB installations because a 4 to 5 man ground crew is needed plus an operator to place the mats. Fabriform installation labor is also lower than conventional concrete labor, because of the need for forming and finishing.
RTC Southern's production is a result of many years of experience of the superintendents and crews. RTC Southern can install upwards of 5,000 SF per day depending on several factors such as Fabriform style and size, application, site conditions, etc. A common Fabriform ditch lining averages around 3,000 SF to 4,000 SF per day. ACB installations are time-consuming because the mats have to be unloaded, precisely laid, and cabled together. Riprap installations usually incorporate only a one-man crew, the track hoe operator; therefore, it can take considerably more time to place rip rap in the bottom and both side slopes of a ditch, especially if the operator has to place from both sides of the ditch. Conventional concrete linings have to be formed, poured, finished and stripped, adding considerable amounts of time to the installation.
Fabriform® is pumped with a fine aggregate concrete; therefore, having our equipment (truck, pump, and concrete truck) extremely close to the installation location is not an absolute necessity. RTC Southern has the ability to pump up to 400' with a conventional setup. For longer distances we can pump up to 1,000,' although increasing the pumping distance may decrease production. Installation of ACBs, riprap and conventional concrete must have all of the equipment very close to the installation location or double handling may be needed.
With the Fabriform® system you have the fabric itself and the concrete grout. The fabric is very economical compared to the other types of revetment systems. The concrete grout is generally about the same price as 3,500 psi concrete, but is dependent on the local market. The material cost for ACBs are usually two to three times more costly than an installed Fabriform system. Rip rap cost can vary depending on the location of the project and can be significantly higher where rock quarries are not close to the jobsite.
The Fabriform® system is a monolithic system that acts as one unit, unlike rip rap that is many pieces which can be displaced by hydraulic flows. A Fabriform® system can be easily designed with greater or lesser attenuation of hydraulic energy and hydraulic friction. Fabriform® can be easily sized to resist hydraulic uplift, and can also be easily designed to relieve hydrostatic pressure beneath (or behind) the system. It can be easily designed to accommodate changing soil and water conditions. All of these criteria can be ECONOMICALLY addressed just by selecting the right style and size of Fabriform®.