What are the advantages of the Portadam system?

The cost of a Portadam system is much lower than an alternative sheet piling system. The system can also be used on uneven bed terrains or slopes and punctures, tears or rips will not cause system failure. Additionally, the system can be installed in flowing water is capable of retaining 100% of system height and will not shift or roll in flowing water. Portadam’s can also be installed on concrete or bedrock as penetration of the stream bed is not required.

Furthermore, the lay-down and prep area requirements are minimal and installation can be accomplished with minimal equipment requirements. The installation process is clean, quiet and does not produce vibration or noise. Finally, as a rental product, there is nothing to purchase, no waste and no disposal cost. Excavated materials are permitted to dry, which makes disposal easier and less costly. The system is environmentally friendly through minimal site disturbance, decreased levels of turbidity and it is easily installed and removed.

Will the environmental permit accept the Portadam system?

The Portadam technology was specifically developed to meet the clean water regulations of the federal, state, and local environmental agencies. Portadam can provide a reference list of those agencies as required.

Do I need to provide any assistance (labor) on site?

Ultimately, the contractor is responsible for the installation of the cofferdam and Portadam’s crew is only providing in-water technical assistance. The contractor is expected to provide supervision for their crew as well as a minimum of two men and one machine operator to install and remove the structure.

Can I install the Portadam system myself?

Yes, this is entirely at the discretion of the contractor as they are ultimately responsible for the installation and removal of the cofferdam system.

What if the dam springs a leak? Can it be fixed in place?

If Portadam develops a puncture or tear some leaking may occur, however it is easily repaired while in place under load. Inflatable dams will usually fail as a result of a puncture or tear.

The river bottom is really soft, can the Portadam be installed here?

The Portadam system can be installed on any base material with enough consistency and mass to support the loaded structure. Also, loading must be considered a function of the maximum anticipated water depth on the outside of the dam. We offer free site surveys (by a qualified Portadam technician) to gather site information, specifically, water depths and linear footages. Portadam does not take soil samples of the subsurface and therefore does not represent or warrant the stability of the subsurface for the Portadam system.

The bottom is solid rock, can the Portadam be installed here?

The Portadam system can be installed on solid rock. On flat, slippery rock and on radical slopes, drilled pins may be required to resist movement. Large, irregular outcrops and ledges may make installation difficult or impractical. Fissures in the rock base could cause higher than normal seepage.

The bottom is concrete, can the Portadam be installed here?

The Portadam system can be installed on concrete surfaces. On flat, slippery concrete and on steep slopes, drilled pins may be required to resist movement.

The bottom is sloped, can the Portadam be installed here?

The Portadam system can be installed on sloped surfaces provided the installation alignment traverses the slope. Surfaces sloping in the direction perpendicular to the structure will change the load angle of the structure. Depending on the water depth, this situation is acceptable to a certain degree. We offer free site surveys (by a qualified Portadam technician) to gather site information to determine if the slope will be acceptable.

The bottom is irregular, can the Portadam be installed here?

The Portadam system is a very flexible structure assembled with adjustable connectors which allow placement over most irregular surfaces. Sandbags can be utilized under the structure legs to flatten out small areas that present installation difficulties.

Can you put pipes through the dam?

Portadam manufactures a special flume, which is integrated into the liner system. The (fabric) boot slides over the piping and makes a watertight connection around it.

How much space does it need from the dam to my excavation?

A rough rule of thumb is 1:1 away from the excavation i.e. if the excavation is 5′ deep, Portadam should not be placed any closer than 5′ from the edge of the excavation. This is highly dependent on the base material under the Portadam structure. Portadam is not an engineering firm and therefore makes no representations or warranties regarding the space requirements for any excavation project.

Will the Portadam hold up the walls of my excavation?

Portadam is utilized strictly as a dewatering barrier (cofferdam) around the perimeter of the area to be excavated above the existing ground line. The customer is required to utilize standard shoring equipment and methods to assure worker safety while working in the trench.

How high is the Portadam?

Portadam is available in heights of 3, 5, 7 and 10 feet and the equipment sections can be combined to meet the specific site requirements and slopes. A project that requires a 10′ high (max.) Portadam cofferdam may also utilize 3′, 5′ and 7′ high equipment where elevations permit, this allows lower rental costs.

What depth of water will it retain?

Portadam equipment is capable of 100% height retention. What does that mean for my project? Unlike inflatable structures which are only capable of retaining 75% of their overall height, Portadam will remain stable and in place even as the water level reaches the top. This simply means that a 10′ high Portadam structure will give you 10′ of protection.

What happens if it is overtopped?

The Portadam structure is designed to hold water to the top and if specified in advance is capable of withstanding over topping. Portadam is sometimes used as an overflow weir structure. The key to this application is to eliminate any possibility of erosion of the base material on which the Portadam structure is installed. Any anticipated overtopping must be carefully planned and prepared for by providing a non-erodible base under and behind the Portadam structure. In certain situations, additional bracing may be required. Since stability of the Portadam structure is dependant on the stability of the foundation on which it is placed, erosion or displacement of the base material could cause the structure to shift. Severe, uncontrolled erosion of the base material could cause collapse. For this reason, it is always best to plan your project using a Portadam structure higher that the anticipated water level fluctuation.

Can Portadam be installed in flowing water?

The Portadam system can be installed in flowing water. The equipment is assembled by people working in the water, so the rule of thumb is, if the workers can stand still against the flow, then the dam can be installed. There are certain situations involving higher flows where our technicians can recommend and design a flow diversion to reduce the flow to a workable range. Our sales staff can arrange a site visit to determine your project requirements and applicability of the system to your situation.

What (velocity) speed / flow can it be installed?

Installation flow velocity depends on the actual site conditions and installation procedure (see #4 above). In shallow water, the dam can be installed in flows up to 2 fps. In deeper water, about 1 fps flow rate is the maximum, but a temporary diversion could be used to make the installation easier.

Will objects / debris floating down the river puncture it? Or knock it over?

Once dewatered, the Portadam structure becomes extremely stable due to directional loading. The liners are made of a nylon or polyester reinforced fabric which is extremely strong. We do not normally have problems with debris or floating object punctures. In extreme situations where a flood flow builds up huge amounts of debris against the dam structure, it can be displaced or knocked over.

What length does the Portadam come in?

Portadam can be designed and built to any size or configuration. The Portadam system is completely modular, which allows the system to be built to the exact length or size required.

Can I purchase it instead of renting it?

For construction related projects, Portadam only rents the product. This is ideal since each job site is remarkably different, allowing contractors to only rent what they need for each project without significant investment in these assets. For that reason, Portadam remains strictly a rental product.

Is there any break in the rental rate for long term rentals?

Portadam rental rates are tiered, which reduces the monthly rental rate from the first to the second month and from the second month to the third month. Every month thereafter remains the same. Portadam can make special concessions for Rentals in excess of eighteen months.

When does the rental start and end?

Rental period begins upon delivery to site and continues until loaded for return to Williamstown, NJ.

Who handles the pumping?

The customer is responsible for all pumping (initial de-watering and 24 hr. maintenance pumping as required, to include any and all seepage, infiltration, groundwater, overflow and precipitation) while Portadam equipment is onsite.

What size pumps will it need?

A number of factors come into play here such as the overall size of the cofferdam, maximum water depth, porosity of the streambed and some other variables. Initial dewatering usually requires larger pump(s), maintenance pumping can only be assessed once initial dewatering has taken place.

What items do I have to provide in support of the Portadam system?

Lifting rig services to handle Portadam equipment each day at site and to transport to site from staging area. Access, clearing, offloading & reloading at site staging area. Sandbags as required. Structure security, maintenance and rental equipment insurance (include flood).

Who designs the Portadam layout?

The cofferdam layout is usually specified by the contractor’s project engineer or project manager. Utilizing the project plan view as a guide, Portadam will perform an inwater survey to determine exact system placement and water depths. Other factors the contractor needs to consider are excavation, excavation depth, limits of construction, permits, clearing of subsurface and bank conditions, etc.

Are there permits required?

Permits are usually required. Portadam does not handle any permitting requirements. Check with the local permitting agencies.