SUBJECT:
Title
Orange Lake Overlook Restoration - Major Site Plan - Waiver to Major Site Plan in Review
19865 N US Hwy 441 Micanopy
Project #2025030052 #32721 Parcel #02709-000-00
JB Pro
DIVISION 10. - KARST TOPOGRAPHY AND HIGH RECHARGE AREAS
CODE states Sec. 6.10.1. - Purpose and intent. Marion County is uniquely situated in a geologic area featuring limestone and rock characteristics identified as karst, promoting the quick and rapid movement of water between the surface and the aquifer. As the aquifer is the vital source of Marion County's potable water, as well as much of the State of Florida, its protection and preservation is essential. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.2. - General requirements. A. An application for any new development or expansion of existing development, located within a high recharge or karst sensitive area as designated by the appropriate water management district or Marion County maps, shall submit an analysis of site conditions in sufficient detail to define hydrologic and geologic conditions which may guide mining, land development, or construction activities on the proposed site. B. An applicant for any new development or expansion of existing development shall depict karst features on the project site and off-site within 200 feet of the project boundary. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.3. - Additional submittal requirements. A. When providing a submittal for the purposes of demonstrating karst feature and high recharge area protection, the following minimal information shall be included: (1) Potentiometric surface map; (2) Geologic bulletins and papers specific to the project area; (3) Geotechnical and hydrogeologic reports or studies, including test borings. The total number of borings shall be determined by the professional responsible for signing and sealing the study; (4) Assessment of sinkhole, cave, lineament, escarpment, solution pipe and other known and potential karst features; and (5) Engineering analysis and recommendations, including: (a) Evaluation of planned site area; and (b) Options and recommendations including but not limited to: 1. Remediation or buffering; 2. Minimization of impervious surfaces; 3. Potential for innovative stormwater collection and protection measures including pre-treatment and shallow drainage retention areas; and 4. Alternatives to stormwater retention basins when soil cover is inadequate to protect the Floridan aquifer. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.4. - Untreated stormwater. No untreated stormwater shall be directed into a karst feature. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.5. - Development restrictions. Development restrictions in high recharge and karst sensitive areas are as follows: A. Businesses or industries which produce, use, or store hazardous materials listed in Section 12.7 shall prepare the proposed development plans in conformance with the requirements of Section 12.8.3, the Florida Administrative Code, and the requirements of this division. B. Non-residential uses shall be set back 200 feet from a sinkhole, unless the sinkhole is remediated or alternative design addressing water quality issues is approved. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.6. - Karst feature remediation. If remediation of a karst feature is proposed, the application for development must include a remediation plan containing all details for the remediation activity. A final certification documenting that the karst feature was successfully remediated in accordance with the plan shall be submitted with the final certifications for the development. The remediation plan and final certification must be signed and sealed by a Professional Engineer or Professional Geologist. Karst features remediated in compliance with this paragraph shall not be required to meet the buffer requirements of this division. (Ord. No. 13-20, § 2, 7-11-2013) Sec.6.10.7. - Karst feature conservation. All new development and expansion of existing development shall provide and maintain a permanent vegetative buffer around any sinkhole, cave, lineament, escarpment, solution pipe, and other known karst features that are not remediated. The buffer shall be entirely within a Conservation Easement. The Conservation Easement shall be clearly delineated, labeled, and described on the applicable plan, and follow the provisions in the Habitat Protection section of this Code. A. Buffer Width. The minimum width of the required karst buffer shall be 150 feet for karst features with a direct connection to the aquifer and 75 feet for karst features with no direct connection to the aquifer, as measured from the outermost closed contour or edge of the escarpment, as applicable, but no greater in width than the contributing watershed. These minimum buffer widths may be reduced if the applicant demonstrates either of the following: (1) A narrower buffer can be calculated using the design methodology for calculating buffer width based on infiltration, as set forth in the Applicant's Handbook for Regulation of Stormwater Management Systems, SJRWMD 2005, as amended; or (2) The lot of record is too small to accommodate permitted development in compliance with the minimum width, in which case the applicant shall, as an alternative, design and construct a stormwater control feature such as, but not limited to, a vegetated swale and/or berm that effectively prevents drainage to the karst feature. B. Design Buffer Use. The karst buffer shall be maintained in permanent vegetative cover. In addition, the following shall be prohibited within the buffer: (1) Buildings, pavement and other impervious surfaces, except sidewalks five feet or less wide may be permitted; (2) Septic tank drain fields and any form of domestic wastewater disposal; (3) Drainage retention areas; and (4) Use of irrigation, fertilizers, and pesticides. C. Native Vegetation. The native vegetation shall be restored, preserved, and maintained to provide a buffer around sinkholes in excess of 50 feet in diameter.
Applicant Request a waiver due to the proposed site plan is under the threshold required for stormwater
LDC 6.13.2.(B)- Minimum requirements
CODE states 6.13.2 B. Calculations shall minimally include: (1) Runoff analysis that reflects the project basin soil type, area, and ground cover based on pre-conditions and post-conditions for ultimate development. (2) Time of concentration and travel time analysis for hydrology and hydraulic systems. (3) Soil boring parameters including the confining layer elevation, estimated seasonal high-water elevation, porosity, and permeability rates as justified in the geotechnical investigation report. (4) Hydrologic stormwater model analysis including all input parameters, supporting calculations, assumptions, documentation for design and results. (5) Hydraulic stormwater model analysis including all input parameters, supporting calculations, assumptions, documentation for design and results. (6) A minimum freeboard of six inches shall be provided for all retention/detention areas. (7) Recovery analysis based on drawdown of the total required volume. (8) Calculations must be consistent with the plan sheets and other supporting details. Calculations shall use standard methodology recognized in the State of Florida, including hand and/or computerized calculations.
Applicant states the proposed site plan is under the threshold required for stormwater
LDC 6.13.4 - Stormwater Quantity Criteria
CODE states A. Methodologies, rainfall distribution and intensities shall be consistent with those approved by the governing water management district. Assumed parameters must be supported by conventional methods. B. Design storms shall consider open or closed basins as provided in Table 6.13-1. C. Discharge conditions (1) All stormwater facilities shall be designed to limit discharges considering open or closed basins per Table 6.13-1. (2) Discharges shall mimic the pre-development condition, match the pre-development location and not exceed the pre-development rate, except when discharging into a stormwater system designed to accept such discharges. (3) The bypass or discharge of offsite runoff, shall be allowed when it mimics the pre-development condition, matches the pre-development location and does not exceed the pre-development rate, except when discharging into a stormwater system designed to accept such discharges. (4) In closed basins with downstream flooding, existing improvements may be included in the pre-development calculations when all of the following apply: (a) The existing improvements were constructed as part of a development with a permitted stormwater system or constructed prior to stormwater permitting requirements; (b) Discharge from the existing improvements are into a private system designed to accept such discharges or a public system; and (c) There is no adverse impact downstream including, but not limited to, flooding of structures or hindering of access. (5) A discharge structure shall be required for all retention/detention areas not designed to retain the entire 100-year 24-hour post-development design storm. (6) Discharge structures shall include a skimmer at a minimum. Design elements such as baffles or other mechanisms suitable for preventing oils, greases, and floating pollutants from discharging out of the facility shall be considered. When discharging from a natural facility, a skimmer may not be required upon approval from the County Engineer or his designee. When a grassed weir is used it shall be constructed with a hard core center or geoweb. D. Recovery. (1)All retention/detention areas shall recover the total volume required to meet the discharge volume limitations within 14 days following the design rainfall event. (2) For retention/detention areas not able to recover the total required volume within 14 days, the stormwater facility volume shall be increased to retain an additional volume of the post minus pre difference in runoff for the 25-year 24-hour design storm when in an open basin or for the post minus pre difference in runoff for the 100-year 24-hour design storm when in a closed basin. The control elevation for retaining this volume shall be no greater than the top of constructed stormwater facility or the easement limits of a natural facility. Credit for the recovered volume through the 14-day duration may be considered to meet this requirement. E. Infiltration or percolation can be considered when establishing the design high and discharge elevation. F. Other design criteria may be used if approved by the County Engineer or his designee.
APPLICANT requests a waiver due to the proposed site plan is under the threshold required for stormwater
LDC 6.13.6 - Stormwater Quality Criteria
CODE states A. Methodology. Stormwater management systems may be designed using a combination of design techniques ranging from traditional to low impact. The method(s) utilized shall focus on enhancing the quality of stormwater discharge and recharge through shallow systems, the processes of adsorption, filtration, denitrification, ion exchange, nutrient uptake, microbial activity, and decomposition. (1) Exemptions. (a) Sites less than ten acres with an industrial use, as defined by North American Industry Classification System. Larger size exemptions will be considered through the waiver process. (b) Existing commercial parcels two acres in size or less. This exemption shall only apply if the parcel is a parcel of record, with the appropriate land use and zoning, on or before the original adoption of the Springs Protection Ordinance 09-17 dated June 2, 2009. Land use changes and rezonings that occur after this date which create a parcel two acres or less are not exempted. (2) Transportation facilities. Public transportation projects that have a contributing drainage area comprised mostly of the road right-of-way and non-developed natural areas are not considered significant contributors of nutrients and shall meet the water quality standards of the governing state agency. Public transportation projects in urbanized or developed areas shall be evaluated for their nutrient loading impact and designed accordingly. Transportation facilities provided as part of a development shall meet the water quality requirements set forth in this Code unless it is clearly demonstrated that drainage is not received from parcels within the development. (3) The following systems shall be considered as meeting the County's stormwater quality criteria: (a) Systems that demonstrate numerically the post-development stormwater quality is equal to or better than the pre-development stormwater quality using methodology approved by the County Engineer or his designee. Consideration shall be for both surface water and groundwater; or (b) Dry retention systems that have a depth of four feet or less, measured from top of bank to pond bottom, and shall have a vegetative cover; or
(c) Dry retention systems that have a depth of six feet or less, measured from top of bank to pond bottom, with side slopes that are no steeper than 4:1 and sodded bottoms; or (d) Wet retention/detention systems, including wetlands, that meet the governing State standards; or (e) Distributed volume. This treatment type shall provide distributed volume within each sub-basin, mimicking the pre-development sub-basin, prior to discharging to the project's stormwater quantity facility. 1. The required volume to be distributed shall be a minimum of 75 percent of the difference between the post-development and the pre-development initial abstraction, not to exceed 1 inch. If the initial abstraction is less than 0.25 inches, a minimum of 0.25 inches shall be used. The initial abstraction shall be calculated using the National Resources Conservation Service Technical Release 55 (NRCS TR-55) methodology. 2. The contributing area shall be of approximately two acres or less. 3. Distributed volume shall be controlled within systems such as, shallow swales, bioretention facilities, or recessed medians located within a right-of-way, drainage right-of-way, drainage easement or conservation easement. 4. When bioretention facilities are used they shall provide retention/detention of stormwater for the basin utilizing vegetated depressions that implement landscaping and soil specifications in the design. 5. Distributed volume upstream of the receiving on-site retention/detention area shall fully recover surface storage within 72 hours. 6. There is no freeboard requirement for systems such as shallow swales, recessed medians or bioretention facilities used to solely achieve distributed volume. 7. Distributed volume shall be allowed within required buffer area if the applicant can demonstrate that the intent of the buffer can still be accomplished. 8. The seasonal high water table shall be a minimum of 1 foot below the invert of the swale or 1 foot below the bottom of the prepared soil matrix of the bioretention facility. B. Alternative treatment techniques. When proposed systems do not meet the above stormwater quality criteria, two of the following alternative treatment techniques shall be implemented and evaluated per contributing basin. (1) Limiting direct discharge. No greater than 15 percent of the project area can be directly discharged to the water quantity facility. Roof area shall not be included in these calculations and may be directly connected. The remaining impervious area shall be conveyed for a minimum distance of 25 feet at a rate no greater than 1.5 fps for a mean annual storm event to the water quantity facility via overland flow or a vegetated swale. Pipe can only be used when crossing under driveways and roads and when directly connecting roof runoff. (2) Pervious parking. Projects that require more than 30 parking spaces shall utilize porous concrete or asphalt material on a minimum of 20 percent of the total parking spaces required. Approved grass parking spaces may also be used as an alternative to meet this requirement. Use of this alternative may be considered throughout the site and not per contributing basin. (3) Stormwater harvesting system. This technique shall provide for the collection and reuse of stormwater or rainwater through the use of cisterns, underground tanks, wet stormwater facilities, rain barrels or other systems, as may be approved by the County Engineer or his designee. These systems must harvest and reuse the first 1 inch of runoff from a minimum of 40 percent of the impervious area. Two alternative treatment techniques will be satisfied when runoff is collected from a minimum of 80 percent of the impervious area. Use of this alternative may be considered throughout the site and not per contributing basin. These systems must provide the following: (a) An overflow or bypass. (b) A drawdown mechanism by use or direct discharge. (c) Reuse for irrigation or other approved purposes to augment a water supply. (4) Site preservation. This treatment type shall provide for the preservation of natural low areas, existing vegetation, and wetlands as well as karst features, when only non- developed, natural areas discharge to the karst feature. A recorded conservation easement shall be established over the area to be preserved and shall not be less than 10 percent of the parcel of record at time of submittal. Marion-friendly landscaping area and groundwater recharge preservation area, when applicable, may be considered toward meeting this criteria. (5) Limit impervious area. This treatment type shall limit the total impervious area to no greater than 50 percent of commercial or industrial parcels or 30 percent of residential subdivisions or 25 percent of residential parcels (when an individual residential improvement is being proposed without road improvements). (6) Other low impact development treatment types. Alternative techniques may be approved by the County Engineer or his designee in which the technique can demonstrate a water quality benefit greater than or equal to the treatment types provided in this division. C. Best Management Practices (BMPs) are characterized as runoff prevention, retention, detention, and pollution prevention. The following BMPs are required and shall be incorporated as part of the project's stormwater management system and demonstrated by a permit from another agency if applicable: (1) Oil/water separator or comparable BMP technology is required for pre-treating runoff from vehicular traffic areas associated with the following practices: (a) Car washes; (b) Auto or marine paint and body shops; (c) Auto, recreational vehicle, commercial truck, tractor-trailer, farm tractor, heavy machinery, or small engine parts, service and repair operations; (d) Automotive fleet operations; and (e) Gas stations, including convenience stores with gas pumps. (2) A minimum of three feet of unconsolidated soil material shall be provided between the surface of any limestone bedrock and the bottom and sides of any stormwater facility. Excavation and backfill of suitable material may be made to meet this criterion. (3) Retention and/or detention facilities shall have a maximum depth of ten feet, as measured between the design high water elevation and the pond bottom for dry facilities, and between the design high water elevation and the normal control water elevation for wet ponds. (4) Other best management practices are encouraged, such as but not limited to routine street sweeping, and fertilizer free zones. When practices such as these are proposed and documented in a manner that is enforceable, the County Engineer may accept these as an additional treatment technique.
APPLICANT requests a waiver due to the proposed site plan is under the threshold required for stormwater.
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