DETENTION PONDS

The use of detention ponds marks the most recent flood prevention method to be used in Trinidad and Tobago. The detention pond at South Quay Port of Spain is now one of three such ponds in the country: another detention pond, the Connector Road Detention Pond,  in the Charlieville/Felicity area, is already in operation and one other, still under construction, is  in the Fairview /Calcutta area. Notable about these other detention ponds is that they are located in central Trinidad, undoubtedly, the most flood prone part in the country.

The South Quay Detention Pond will be part of the arsenal to combat flooding in the capital.  It has been designed to reduce the amount of standing water on the Eastern Main Road at the entrance to Port of Spain and thereby significantly reducing flooding in that area.

As with central Trinidad, Port of Spain has also long experienced recurrent flooding, which has not only led to much frustration of the many persons that live and traverse through the capital on a daily basis, but has helped to negate the notion  of Port of Spain being regarded as one of the most developed cities in the region.

Prior to and continuing in the current rainy season, the Ministry of Works and Infrastructure, through its Drainage Division, has embarked upon  several measures to prevent and alleviate flooding in Port of Spain and throughout the country. The first of these is the conducting of basin studies.

Basin Studies

These studies entail a holistic study of specific catchment areas that experience perennial flooding. These areas that have been have been identified are:

• Beetham Gardens and environs
• Bull Bull
• Soledad
• Diego Martin
• Maraval

The studies involve analysis of the entire basin/catchment area. Upon completion of the analysis, feasible and sustainable solutions will be sought and implemented.

In addition to basin studies the Drainage Division also embarked upon a "Clean the Drains" campaign whereby most of the city drains have been cleared of silt and debris. In this exercise, both surface and underground drains were cleaned using suction machines, power hoses and manual labour.

   What is a detention or retention stormwater facility?

A detention basin is constructed to essentially catch and temporarily store storm water. An infiltration basin, pollution basin, or storm basin can form part of a detention system.

How do R/D Facilities Work?

A detention pond stores accumulated storm water runoff and slowly releases it  downstream. Rains fall on a particular catchment area and usually finds its way (naturally or manmade) to the lowest point of concentration.

 
A flow control structure regulates the release rate of the stored water. This regulation is designed to allow either a pre development flow rate or reduced rate of flow.

Why is storm-water runoff a problem?

As we cut woodlands, clear land, pave roads and parking lots, and construct houses and buildings, we change the permeability of the ground. Falling rain has fewer places to soak in gradually.  Runoff on hard surfaces occurs faster and in greater volumes. Increased storm-water runoff may increase flood risk and affect erosion, water pollution, and destroy habitats and eco-structures.

How are they formed?

Detention basins/ponds may be formed from earthen structures or composite materials. These may vary in size and complexity depending on the size of the catchment it was designed to serve. They are basically storm water impoundments created by an embankment or excavation with a restricted outlet flow capacity.