The Krupaseep

Next Generation Seepage Meter
Kissimmee River Ground Water/Surface Water Study

( Click on the image for larger view )

( Click on the image for larger view )

The scientific community has made an intense effort to understand the principles that drive the exchange of ground water to the surface water and vice versa. Today we are still manually measuring the fluid exchange between the ground water and surface water with cut-off 55-gallon drums fitted with plastic bags. There is no water quality sampling from within the drums because of anoxic conditions within the drums' closed system. Modern technology has allowed us for the first time to begin to understand the chemistry and flow conditions in-situ in rivers and wetlands.

Understanding the exchange between the surface water and ground water has been a problem worldwide since measurements of the exchanges were first recorded in the late 1950's. The seepage meter methodology of the 50's has not changed significantly. Today's method of measuring the flux at the interface between an aquifer and a river channel or a wetland utilizes a crude seepage-metering device, fabricated from the top of a 55-gallon drum, cut off and driven into the river bottom with a sledgehammer. A plastic bag that is half filled with a known volume of water is attached to the hole at the top of the drum. The bag is left attached to the drum underwater for a period of time. The difference (gain or loss of water in the bag) is noted. This difference constitutes the flux across the cross sectional area of the drum per unit of time. A gain of water in the bag reflects discharge from the aquifer to the river channel wetland. Conversely, a loss of water from the bag reflects recharge to the aquifer from the river channel or wetland.

The study of the quality of water leaving or recharging the aquifer has only been attempted in several small studies. The investigators concluded that water quality from the seepage-metering device could not be used to assess nutrient loads from the ground water because of the anaerobic conditions within the drum.

In early 1996, the Kissimmee River Restoration Division (KRR) issued an RFP to evaluate a groundwater monitoring network designed by Jeff Herr and Dave Butler of the South Florida Water Management District. For this, the District hired Dr. Sam Upchurch of ERM South, Inc. through the expert assistance program. Dr. Upchurch evaluated and approved the proposed ground water monitoring network with minor modifications. As part of a second RFP, Dr. Tom Belanger of Florida Institute of Technology was selected to evaluate several methodologies for studying the exchange of the surface water and ground water at the monitoring network locations on the Kissimmee River. The RFP required an evaluation of conventional flow net analysis, conventional in-situ seepage meter fluxes, drive points for hydrostatic head measurements in the river bottom, water levels in the onshore and river bottom piezometers, in-situ flow measurements, as well as an evaluation of a proposed design for a new seepage meter device previously developed by Steve Krupa of the South Florida Water Management District. For the design of the new seepage meter device, an in-depth literature search was conducted to gather information on seepage meter results, testing, analysis and problems. Based on results of the literature search, Steve Krupa developed and constructed two prototypes for a new generation of seepage meter, which Dr. Upchurch nicknamed the "Krupaseep".

The prototypes, which utilize translucent polycarbonate plastic domes, were fabricated in two sizes. The largest dome size is 3-feet in diameter with a cross sectional area of 7.07 square feet (0.66 square meters). The dome is fitted with a 16-inch (40.64 cm) vertical skirt to anchor into deep organic muds. The smaller dome is 2-feet in diameter with a cross sectional area of 3.14 square feet (0.29 square meters) with an 8-inch (20.32 cm) vertical skirt. A port was cut into the top of each dome to allow flow-though of water. A flow meter was installed in the port. As an added feature, water quality meters were installed on the inside and the outside of the dome. When completed, the domes were then pressed into the river bottom until the top of each dome was 14 inches above the mudline. The monitoring equipment on each dome was tethered back to computers on shore.

The Krupaseep--The early version of the onshore data logger
and solar panels for the Krupaseep seepage meter.
Both seepage domes are to the right of the tripod/solar panel system

The Krupaseep is powered by batteries that are recharged by two river-side solar panels (one 20 Watt and one 60 Watt). The batteries provide voltage to drive both the flow meter computer and also the CR-10 data logger. The computer records real-time water quality data on the inside and outside of the seepage meter and records the inflow or outflow (flux) via heat pulse technology.

The system is currently restricted to a radial operating distance of 160 feet from the computers. The data logger also records system battery voltages (flow meter and CR-10) and photosynthesis-activated radiation (PAR) allowing us to understand the oxygen curves inside and outside of the seepage meter. The Krupaseep domes have also been set up to allow remote water quality sampling via masterflex hoses mounted on both the internal and external surfaces of the dome and a peristaltic pump located onshore. The seepage meters have been on field trials since September 1997. Currently, weekly maintenance is required because of the harsh conditions of the C-38 Channel. The Okeechobee Field Station has been providing the divers who perform the river-bottom installation and service. The West Palm Beach field station has also been providing assistance with back-up dive crew staff.

Steve Krupa works on the new interface box/solar panel
for the Krupaseep seepage meter at Pool C, Site C.