Old Jamestown Association

P.O. Box 2223
Florissant, MO 63032
ph: 314-831-5570
prautes@aol.com

Karst Preservation Area

The St. Louis County Council has established the Karst Preservation Zoning District, which is entirely within the Old Jamestown area. The legislation recognizes the Florissant Karst as an environmentally unique area in north St. Louis County and preserves the natural drainage system of the sinkholes for future generations. A preservation proposal by the Association was submitted to the County in April 2008.

Documents related to the Association's proposal for recognition of the Florissant Karst Area:

Florissant Karst Boundary Map
Environmental Features (excerpted from April 1988 Community Study)
OJA Statement at March 3, 2009, County Council Meeting
Karst Preservation Proposal
Karst Ordinance
Human Modification of Karst in the St. Louis area, Missouri, Robert Criss

Aside from the natural beauty of the rugged terrain and the abundant wildlife, the geologic formations in the Old Jamestown Area are unique. The underlying karst limestone formations are reflected on the surface by sinkholes created after hundreds of thousands of years of a critical combination of underground water flow, dissolvement of the limestone, the weight of the overburden soil, collapse of the soil/rock structure, and then surface runoff water flowing into the ground openings to cause further erosion. More than four square miles of the Old Jamestown Area have been identified by the Missouri Department of Natural Resources as karst formations. Their report, after a field investigation in February 1988, said, "The karst area is so unique; preserving its natural state as much as possible would certainly be desirable."

The significance of what is generally referred to as the "Florissant karst" is well documented by virtually every book on Missouri geology. Taken from the Land Element of the St. Louis County 1973 General Plan..."The Florissant karst is recognized as having the finest example of deep funnel-shaped sinkholes in the Central United States."

The karst formation will always be active. Taken from the Old Jamestown Association Position Statement of September 4, 1987..."Most people think of sinkholes as a geological feature that has occurred during the past thousands of years. That is true in some cases, but it is also true that sinkholes constitute a continuously changing configuration of the surface in a karst terrain. We are prepared to show you sinkholes that have recently occurred, ponds that have drained because of sinkholes, the effects of creep as the sides of sinkholes move laterally into the holes, and forty foot deep ravines eroded by surface water drainage into sinkholes." (A copy of the Position Statement, which includes an extensive segment about sinkholes, is provided with initial membership, $3.00 for additional copies.)

KARST PRESERVATION ZONING DISTRICT ORDINANCE ENACTED

The St. Louis County Council enacted final legislation on December 29, 2009 to establish the Karst Preservation Zoning District (KP) in the Old Jamestown Area of unincorporated North St. Louis County. The newly created Zoning District recognizes the environmental uniqueness of the 4.2 square mile area of karst geology known for many years by geologists as the“Florissant Karst”. Its significant characteristic is the intensely spaced, deep, steep sided sinkholes into which all the surface runoff water drains. The water draining into sinkholes can travel rapidly through open cracks and crevices and quickly contaminate the underground water supply over a very large area. Sinkholes can sometimes be unstable as a result of soil erosion and subsidence of the underlying geological formations.

General provisions of the new Zoning District include:

· Increased construction setbacks from sinkholes.

· Permitted Uses remain the same as present Non-Urban Uses.

· Essentially all Conditional Uses remain the same as Non-Urban.

· Geotechnincal report required for most projects.

· Alteration of the natural drainage system not permitted.

· Discharge of developed storm water into sinkholes not permitted.

· Three acre minimum lot size required for single family structures.

COUNTY RECEIVES AWARD FOR CREATION OF NEW ZONING DISTRICT

On March 29 the St. Louis County Planning Department won an Outstanding Achievement in Planning award by the American Planning Association-Metro St. Louis for the new Karst Preservation Zoning District. The zoning district was developed to protect the landscape in a four square mile area in the Old Jamestown community in North St. Louis County that is recognized as being one of the finest examples of deep funnel shaped sinkholes in the central United States.

The purpose of the new district is to preserve this natural karst/sinkhole area while continuing low intensity development within the constraints of the geology. New setbacks from sinkholes were established and geotechnical reports are required prior to future development being authorized.

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P.O. Box 2223
Florissant, MO 63032
ph: 314-831-5570
prautes@aol.com