Tag Archive - Hydrogeology

Water Use Changes in Northeast Florida

July 30, 2010 in Geology with 1 Comment

The St. Johns River Water Management District (SJRWMD) is proposing regulatory changes to the current Environmental Resource Permitting (ERP) and Consumptive Use Permitting (CUP) programs that could have significant impact on businesses in Northeast Florida.

The changes are being implemented to assist in water conservation, and due to a concern that continued development will put our area into the category as a Priority Water Resource Caution Area.

You see, our primary source of drinking water in Northeast Florida is the Floridan Aquifer. This “underground river” of water is being used at a rate greater than the natural ecosystem can replenish it, and creating unacceptable impacts.

As the availability of fresh water from the Floridan Aquifer becomes a concern, we have to look at:

  • Additional water conservation measures, and
  • Alternative Water Supply (AWS) sources to meet our water needs, including desalinization of ocean water, surface water body withdrawls and reuse of reclaimed water.

Both of these efforts are ongoing.

The currently proposed regulatory changes include amending the SJRWMD rules to include water conservation requirements in the ERP program and to require consolidated processing of ERP and CUP applications for specified activities. The specified activities include all ERP applications that will involve irrigation of landscape, golf courses or recreational areas. These applicants will have to develop and implement a water conservation plan to obtain a permit.

If these changes are of an interest to you, please feel free to contact me here or at my company website, Isotropy, Inc. for further information and to see how it may affect your business.

Preservation of The Freshwater Lens on New Providence Island, The Bahamas

April 16, 2010 in Geology with 0 Comments

The Lynden Pindling International Airport (LPIA) is located in the central part of New Providence Island and provides local and international air travel connections. LPIA is the busiest airport in The Bahamas and is undergoing an expansion. The airport expansion includes the addition of a new building that will handle passenger traffic traveling to and from destinations within The United States of America.

The most cost-effective way to cool the large buildings like those at LPIA in The Bahamas is through heat-exchange. This process basically takes large quantities of groundwater, which is at a constant temperature of 70-72 degrees Farenheit, and a heat exchanger is used to transfer the cooling capacity of the groundwater to the air that is then circulated through the building.

Isotropy, Inc. was subcontracted through Sentinel Drilling of The Bahamas, Ltd. to assist with the hydrogeological services for the LPIA project. Our services included assisting with the design and testing of groundwater wells for the heat exchange system. The wells include two production wells and two return wells. The groundwater production wells remove groundwater at a depth of 320 to 400 feet below land surface, and are each 12” in diameter.

Our services included determining if the groundwater withdrawals would have an adverse affect on the surficial freshwater lens, a valuable resource that the local government would like to preserve. The freshwater lens present in the subsurface on New Providence Island is aerially extensive and used locally as a water source tapped by private wells. The freshwater lens is recharged by the infiltration of rainwater, as rainfall at this location exceeds the local evapotranspiration. Generally, the geometry of the lens is such that it is thickest in the central part of the island, and thins toward the coast. The freshwater lens is between 20 and 50 feet thick in the area of the airport.

A large-scale pump test was performed to assist in determining if the new groundwater withdrawals at the airport would affect the freshwater lens. Water levels were monitored in the shallow and deep aquifers during the pump test. The information collected in the field was complied and analyzed, and it has been determined that there does not appear that an impact to the freshwater lens will occur through the use of the groundwater wells at the airport. The deep aquifer is very porous, and the groundwater wells installed at the site have a large capacity to produce groundwater. Additionally, the groundwater return wells installed at the property are designed to assist in eliminating impacts to the shallow freshwater lens. The return wells are open from 200 to 300 feet below land surface, and are located northeast of the production wells. The return wells provide discharge of the heat-exchange discharge water to the aquifer at a shallower depth than the production wells, helping to block affects to the shallow freshwater lens.

This project has been very exciting to work on. I’m very grateful to Sentinel Drilling and the Swaby’s for the opportunity to assist with this high-profile project. It is always a pleasure to work with the people of The Bahamas.

Good News

March 20, 2010 in Geology with 0 Comments

About 4 years ago now God blessed me with an absolute miracle. A dear friend included me on a project team at Atlantis, in the Bahamas, for the Phase III Expansion Project, as the Project Hydrogeologist.

That summer, I spent more time in the Bahamas than at home, and got to know a few of the good Christian people there very well. One of the families that I got to know was the Swaby’s. Brendan and Julie Swaby are very dedicated Christians, and own Sentinel Drilling of the Bahamas, Ltd. Since then, they have continued to plug me into projects, and I’ve been able to work on several water resources projects there, including reverse osmosis (drinking water) and heat-exchange cooling water uses.

I’m currently working on a project at the Lynden Pindling International Airport on New Providence Island. I’ve been waiting to go back there for about two months now to complete my part of the on-site project work that includes a detailed hydrogeological analysis of the new groundwater wells that will provide the water for the heat-exchange cooling system for the new structure at the airport.

Yesterday I got the news that…

“yo mon, we’re ready!!”

and

I have been invited to attend the ceremony celebrating the completion of the super structure for the project.

… and they occur at the same time (yep, His timing is PERFECT once again!!)

BONUS TIME, THANK YOU LORD!!! All I can say is… what an incredible God we have, I’m extremely humbled and grateful.

'til their cup overflows (Part 2 of 3)

March 1, 2010 in Geology with 0 Comments

(Part 2 in a series about the water crisis in Haiti)

… the water that goes into the cup…

It’s helpful to understand a little more about the country of Haiti to put the water situation into perspective… According to the United States Army Corps of Engineers (US ACOE), Haiti has an average annual rainfall of 55 inches. That amount is substantial, but it is also highly variable depending on where you are in the country. Variations in the geology and precipitation affect the availability of water in Haiti.

If we think of the water resources in Haiti in terms of Surface Water and Ground Water, and at the same time focus our discussion on the geographical area of Port-au-Prince (the largest population center in the country, and the area receiving the most damage from the earthquake), we find can define some specific water supply challenges in Haiti.

Surface water is perennially available in this geographical area from two major streams that originate in the mountains to the east of Port-au-Prince. The municipal water system in the city does not use any of the surface water for its supply as the water is heavily polluted near the city from human sewage, solid wastes and industrial chemical contamination. However, for much of the city’s population, the municipal system does not provide water (the municipal system only provides water for approximately 1/3 of the population). The only source of water for the remainder of the population is from the contaminated sources, including the two major streams, along with smaller streams, irrigation ditches, and the city’s storm water drains. This usage leads to increased risk for the people of developing malaria and Dengue fever, which are endemic to the area, and gastrointestinal diseases and food poisoning, with children and seniors being at the highest risk.

The subsurface geology in the area of Port-au-Prince is highly variable and, consequently, so is the availability of ground water as a resource. The surficial and near-surface soils and rock in the area consist of alluvial and carbonate deposits as well as sandstones and conglomerates. Some of the alluvial deposits also lie within an area affected by saltwater intrusion and are, therefore, not desirable for use as a water resource. Springs are also prevalent in the area south of the city. The main sources of water for the municipal system are from two well fields to the east of the city, and from a series of springs to the south. These sources are all facing major problems that are decreasing the quantity and quality of water entering the municipal system.

Water is obviously a precious resource that we can’t live without, imagine living in Haiti where clean drinking water is not a given like it is for most of us… what else is there in your life that you feel is absolutely necessary to live? Do you think the people of Haiti would answer this question in the same way?