Portadam is available in different heights. 3', 5', 7' and 10' high Portadam equipment sections are used, which can be mixed and matched to suit specific site requirements and slopes. A project that requires a 10' high (max.) Portadam cofferdam may also utilize 3', 5' and 7' high equipment as well where elevations permit, this allows lower rental costs. 12' high Portadam equipment is available for use in certain situations where the base material is solid (rock, concrete, etc.) and the flow characteristics are minimal. The 12' high Portadam is only quoted on a special project basis after site information is verified.

2) 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.

3) What happens if it is overtopped?

The Portadam structure is designed to hold water to the top and 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.

4) 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.

5) 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 maximum, but temporary diversion could be used to make the installation easier.

6) 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.

7) 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.

8) Can I purchase it istead of renting it?

Portadam is engineered and designed for each specific project location. A "cookie cutter" Portadam system that can be utilized at different locations does not exist because different locations have different conditions and dewatering requirements. For that reason, Portadam remains strictly a rental product.

9) Is thereany 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.

10) When does the rental start and end?

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

11) 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.

12) 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.

13) 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).

14) Who designs the Portadam layout?

The cofferdam layout is usually specified by the project engineer or project manager. Utilizing the project planview as a guide, Portadam will perform an inwater survey to determine exact system placement. Other factors considered are excavation, excavation depth, limits of construction, permits etc.

15) Are there permits required?

Permits are usually required. Check with the local permitting agencies.

16) What are the advantages of the Portadam system?

Cost is much lower than the alternative sheet piling. Can be used on uneven bed terrains or slopes. Punctures, tears or rips will not cause system failure. Can be installed in flowing water. Capable of retaining 100% of system height. Will not shift or roll in flowing water. Can be installed on concrete or bedrock. Penetration of the stream bed is not required. Lay-down and prep area requirements are minimal. Installation can be accomplished with minimal equipment requirements. Installation process is clean, quiet and does not produce vibration or noise. 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. Is environmentally friendly, minimal site disturbance, contains turbidity, easily installed and removed.

17) 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.

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

Customer is expected to provide on-site labor to assist with installation and removal (min. 2 men).

19) Can I install the Portadam system myself?

3' or 5' high Portadam equipment can be installed by the customer with the proper training and personel. 7' & 10' high dam equipment require a qualified Portadam inwater installation crew.

20) 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.

21) 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, including sub-bottom probes, to determine applicability of the Portadam system for your project site. In some situations, the technician may determine that placing a geo-fabric under the base of the support structure will offer enough load distribution to accommodate soft bottom installations.

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 applicability of the Portadam system for your project site.

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.

22) Can you put pipes through the dam?

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

23) 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.

24) 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.