REFERENCES AND DESIGN AIDS FOR THE ENVIRONMENTAL RESOURCE PERMIT APPLICANT S HANDBOOK VOLUME I

Transcription

1 REFERENCES AND DESIGN AIDS FOR THE ENVIRONMENTAL RESOURCE PERMIT APPLICANT S HANDBOOK VOLUME I These References and Design Aids are not incorporated by reference in Chapter , F.A.C., and therefore do not constitute rules of the Agencies. They are intended solely to provide applicants with useful tools, example calculations, and design suggestions that may assist in the design of a project under Chapter , F.A.C. FOR USE STATEWIDE BY AND FOR THE: FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION AND NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT SUWANNEE RIVER WATER MANAGEMENT DISTRICT ST. JOHNS RIVER WATER MANAGEMENT DISTRICT SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT SOUTH FLORIDA WATER MANAGEMENT DISTRICT March 1, 2013

2 TABLE OF CONTENTS DA 1 Mitigation Ratio Historical Guidance... 1 DA 2 Design and Performance Guidance for an Individual Private, Residential Single-family Residence Involving Dredging or Filling in Wetlands or Other Surface Waters... 1 DA 3 Sediment Sump Design Example... 1 DA 4 Critical Habitat Maps for Johnson s Seagrass... 1 DA 5 Critical Habitat Maps for the Smalltooth Sawfish... 1 DA 6 HELPFUL INTERNET LINKS... 1 DEP-WMD AH Volume I Design Aids March 1, 2013 DA - i

3 DA 1 Mitigation Ratio Historical Guidance DA Introduction The following discussion is applicable only to projects that qualify for grandfathering under Sections (11), (12)(a), (13), (14), (15), or (16), F.S., and for use with certain mitigation banks that were designed and permitted using mitigation ratios. This guidance was previously contained in the Applicant s Handbooks and Basis of Review used by each water management district and the Department prior to the adoption of the Statewide Environmental Resource Permit Rule (Chapter , F.A.C., effective [effective date]), except within the Northwest Florida Water Management District. This guidance also was generally applicable to the wetland resource permit rule Chapter , F.A.C., after adoption of the Warren S. Henderson Protection Act in The use of this guidance was superseded upon adoption of the Uniform Mitigation Assessment Rule, Chapter , on February 2, was previously: Suwannee River Water Management District ERP Applicant s Handbook St. Johns River Water Management District Applicant s Handbook: Management and Storage of Surface Waters Southwest Florida Water Management District Basis of Review for Environmental Resource Permit Applications South Florida Water Management District Basis of Review for Environmental Resource Permit Applications The numbering of the sections of this guidance as contained in the above Handbooks and Basis of Review documents has been retained to assist users, except that the Chapter numbers 12, 3, and 4, above, have been replaced by DA-I (for Design Aid for Volume I) when the reference was to the above chapter numbers. However, the X appearing in section DA-I.3.2.1(a) should be replaced with the 12, 3, or 4 applicable to the District where the mitigation is proposed. Other than those changes, the section numbing from the above documents has been retained. DA Mitigation Ratio Guidelines Subsections DA-I DA-I establish ratios for the acreage of mitigation required compared to the acreage which is adversely impacted by regulated activities. Ranges of ratios are provided below for certain specific types of mitigation, including creation, restoration, enhancement and preservation. The difference between the ranges of ratios provided for mitigation types is based on the degree of improvement in ecological value expected from each type. Creation and restoration are assigned the lowest range of ratios as these activities, when successfully conducted, add new wetlands or other surface waters which provide the same or similar functions as the areas adversely impacted. The range of ratios established for enhancement is higher than that for creation and restoration, as the area being enhanced currently provides a degree of the desired functions, and this type of mitigation serves to increase, rather than create, those functions. Preservation differs from the other types of mitigation in that it does not serve to DEP-WMD AH Volume I Design Aids Mitigation Ratio Guidelines March 1, 2013 DA 1-1

4 improve the existing ecological value of an area in the short term. However, preservation does provide benefits as it can ensure that the values of the preserved area are protected and maintained in the long term, particularly when these values are not fully protected under existing regulatory programs. Therefore, the range of ratios established for preservation is higher than those for other types of mitigation. These ratios are provided as guidelines for preliminary planning purposes only. The actual ratio needed to offset adverse impacts may be higher or lower based on a consideration of the factors listed in subsections DA-I and DA-I For example, in instances where the proposed system results in only a small loss of ecological value in the impacted area, such as cases involving impacts to areas of low ecological value or cases where the proposed system results in a small reduction of ecological value of the impacted area, then the actual mitigation ratio would normally be in the lower end of or below the range. For other types of mitigation, ratios will be determined based upon the reduction in quality and relative value of the functions of the areas adversely impacted as compared to the expected improvement in quality and value of the functions of the mitigation area. DA Creation, Restoration and Enhancement When considering creation, restoration and enhancement as mitigation, the following factors will be considered to determine whether the mitigation proposal will offset the proposed impacts and to determine the appropriate mitigation ratio: (a) (b) (c) (d) (e) (f) (g) The reduction in quality and relative value of the function of the areas adversely impacted, including the factors listed in subsection X.2.2.3, as compared to the proposed improvement in quality and value of the functions of the area to be created, restored or enhanced. Any special designation or classification of the affected area. The presence and abundance of nuisance and exotic plants within the area to be adversely impacted. The hydrologic condition of the area to be adversely impacted and the degree to which it has been altered relative to the historic condition. The length of time expected to elapse before the functions of the area adversely impacted will be offset. The likelihood of mitigation success. For mine reclamation activities subject to chapter 211, F.S., part II, whether the ratio is consistent with the mine reclamation plan submitted pursuant to chapter 378, F.S. DA Creation and restoration have the potential to result in similar benefits, if they can be successfully accomplished. Therefore, the ratio ranges given below for these two types of mitigation are the same. Restoration is usually preferred over creation as it often has a greater chance of success due to soil characteristic, hydrologic regime, landscape position or other factors that favor re-establishment of wetland or other surface water communities. Restoration ratios will generally be at the lower DEP-WMD AH Volume I Design Aids Mitigation Ratio Guidelines March 1, 2013 DA 1-2

5 end of the ratio ranges within the guidelines below. The following ratio guidelines will be used to estimate the acreage of wetland restoration or creation required: (a) Mangrove swamps, cypress swamps, and hardwood swamps - 2:1 to 5:1 (acres created or restored: acres impacted). (b) Saltwater marshes and freshwater marshes - 1.5:1 to 4:1 (acres created or restored: acres impacted). DA DA The ratio guidelines for use in the estimation of the acreage of wetland enhancement will range from 4:1 to 20:1 (acres enhanced: acres impacted). Preservation (a) (b) Preservation of important ecosystems can provide an improved level of protection over current regulatory programs. The District will consider as mitigation the preservation, by donation or conservation easement or other comparable land use restriction, of wetlands, other surface waters, or uplands. Conservation easements or restrictions must be consistent with the requirements of subsection DA-I.3.8. In many cases it is not expected that preservation alone will be sufficient to offset adverse impacts. Preservation will most frequently be approved in combination with other mitigation measures. When considering preservation as mitigation, the following factors will be considered to determine whether the preservation parcel would offset the proposed impacts and to determine the appropriate mitigation ratio. 1. The reduction in quality and relative value of the functions of the areas adversely impacted, including those factors listed in subsection DA-I.2.2.3, as compared to the quality and value of the functions of the area to be preserved and the additional protection provided to these functions by the proposed preservation. Factors used in determining this additional level of protection include the extent and likelihood that the land to be preserved would be adversely impacted if it were not preserved, considering the protection provided by existing regulations and land use restrictions. 2. Any special designation or classification of the affected area. 3. The presence and abundance of nuisance and exotic plants within the area to be adversely impacted. 4. The ecological and hydrological relationship between wetlands, other surface waters, and uplands to be preserved. 5. The extent to which proposed management activities on the area to be preserved promote natural ecological conditions, such as natural fire patterns. DEP-WMD AH Volume I Design Aids Mitigation Ratio Guidelines March 1, 2013 DA 1-3

6 6. The proximity of the area to be preserved to areas of national, state, or regional ecological significance, such as national or state parks, Outstanding Florida Waters, and other regionally significant ecological resources or habitats, such as lands acquired or to be acquired through governmental or non-profit land acquisition programs for environmental conservation, and whether the areas to be preserved include corridors between these habitats. 7. The extent to which the preserved area provides habitat for fish and wildlife, especially listed species. 8. Any special designation or classification of the area to be preserved. 9. The extent of invasion of nuisance and exotic species within the area to be preserved. (c) Wetland and other surface water preservation ratios. Since wetlands and other surface waters are, to a large extent, protected by existing regulations, the ratio guideline for preservation of wetlands and other surface waters is substantially higher than for restoration and creation. The ratio guideline for wetland and other surface water preservation will be 10:1 to 60:1 (acreage wetlands and other surface waters preserved to acreage impacted). (d) Upland preservation ratios. Many wildlife species that are aquatic or wetland dependent spend critical portions of their life cycles in uplands. Uplands function as the contributing watershed to wetlands and are necessary to maintain the ecological value of those wetlands. Because of these values, the preservation of certain uplands may be appropriate for full or partial mitigation of wetland impacts, impacts to the upland portion of the riparian habitat protection zones described in subsections and , and impacts to uplands that are used by listed aquatic or wetland dependent species as described in subsection DA-I.2.7(b). The ratio guideline for upland preservation will be 3:1 to 20:1 (acreage of uplands preserved to acreage impacted). DEP-WMD AH Volume I Design Aids Mitigation Ratio Guidelines March 1, 2013 DA 1-4

7 DA 2 Design and Performance Guidance for an Individual Private, Residential Single-family Residence Involving Dredging or Filling in Wetlands or Other Surface Waters This section contains examples and suggestions intended to aid applicants in providing a more complete application for an Environmental Resource Permit to construct an individual, private single-family residence involving some impacts to wetlands. Please note that the information contained in this section is provided for guidance purposes. It does not constitute rule criteria and is not to be used in lieu of adopted criteria or in a manner which is inconsistent with adopted rules. This information is intended to provide guidance for select situations. More elaborate analysis of the project may be needed depending on site topography, soils, existing development, receiving water body location and water quality classification, development density, and wetland preserve areas. Individual, Private Single-Family Home Projects In order to obtain an Environmental Resource Permit to construct an individual, private single-family home involving some impacts to wetlands, an applicant must provide reasonable assurance that the project: 1. eliminates and reduces impacts to wetlands as much as possible 2. won t cause or contribute to flooding (water quantity), 3. will maintain pre-development drainage flows as much as possible, AND 4. won t contribute to water pollution (water quality). The following should be considered by an applicant and should be described in the application and shown on the plans where possible. Eliminate and reduce any impacts to wetlands as much as possible. This may include changing the proposed layout for the home to utilize more upland area. It may include reducing the footprint of the house, driveway, deck, and pool. It may include reducing the size of the fill pad or constructing a fill pad with stem walls instead of sloping sides. Department or Water Management District staff can assist in determining where the wetlands on a property are located. Please note that an applicant may be required to provide mitigation for wetland impacts that remain (cannot be eliminated or reduced.) Please see figures 1a and 1b for an example: Figure 1a. Single-family home project that does not eliminate and reduce wetland impacts. Figure 1b. Single-family home project that eliminates and reduces wetland impacts DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-1

8 Reduce the amount of impervious surface proposed for your project. This will reduce the amount of runoff produced after a rain storm (water quantity). (Did you know that a 1/4 inch of rainfall on a 2,000 ft 2 roof produces 312 gallons of runoff?) Efforts to reduce the amount of impervious and areas where alternative design and construction techniques or alternative construction materials will be used should be described in the application and shown on the plans where possible. Ways to reduce the amount of impervious surface can include, but are not limited to: Reducing the size of the home. Reducing or eliminating concrete decks such as pool decks or patios. Using pea gravel or paving stones to construct sidewalks and other external walkways instead of solid concrete. Constructing the driveway with two wheel tracks with grass in the middle instead of solid concrete or asphalt. See Figure 2a. Figure 2a. (Source: Google Images.) Construct the driveway using gravel (not limerock) instead of solid concrete or asphalt. See Figure 2b. Figure 2b (Source: Google Images.) Construct the driveway using paving stones with grass in between instead of solid concrete or asphalt. See Figure 2c. Figure 2c (Source: Google Images.) DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-1

9 Construct the driveway with gravel, pavers, or wheel tracks and invert the crown, or center line of the driveway so that runoff flows toward the middle and not to the outside edges. See Figure 2d. Figure 2d. Example driveway cross section. (Note: scale is exaggerated.) As much as possible, direct stormwater runoff from rooftops and other impervious surfaces onto grassed areas or into rain gardens, landscaping and flower beds. Doing this will slow down the runoff allowing some of it to percolate into the ground or evaporate into the air, which will reduce the chances of causing offsite flooding. Efforts to minimize and redirect stormwater runoff to grassed or landscaped areas should be described in the application and shown on the plans to the extent possible. Please see Figures 3a and 3b, below. Figure 3a. Roof gutter down spout draining onto a concrete driveway Figure 3b. Roof gutter down spout draining onto grass Fill material to be used for the house pad and/or driveway must be clean (without rubbish or vegetative material) and it should drain well. Specifications for the fill material to be used in the project should be included in the supporting information submitted with the permit application. The pre-development drainage patterns must be maintained as much as possible. Adding vegetated swales and/or buffer strips to intercept and direct runoff to pre-development locations may be necessary. Please see figures 4a and 4b, below, for an example: DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-2

10 Figure 4a. Pre-development drainage pattern is toward the wetland Figure 4b. Post development - property grading and swales direct runoff along the property boundary toward the wetland and a culvert under the driveway maintains flow in the drainage ditch The following tables provide estimations of the volume of runoff that swales of different lengths can provide: DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-3

11 DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-4

12 The following web sites may provide the applicant with additional information and ideas for their project: Geographical information including water bodies, drainage basins and approximate wetland areas can be found at DEP s Water Data Central - Check County websites for a Water Atlas or similar web page Information on the type of soils and the soil characteristics for an area can be found at the USDA s Natural Resources Conservation Service (NRCS) Soils website at Information on flood zones can be found at the FEMA website at Information on Low Impact Development can be found at the EPA s website at DEP-WMD AH Volume I Design Aids Guidelines for SFRs March 1, 2013 DA 2-5

13 DA 3 Sediment Sump Design Example A horizontal-flow sump or sediment basin must remove the particles under peak flow conditions. The length of the sediment sump or basin will be governed by the depth required by the settling velocity of the particle, and the cross-sectional area will be governed by the rate of flow. A length to depth ratio for the sediment sump or basin can be calculated: Flow through velocity (V d) = (length of sump (l)*settling velocity (V s))/depth of sump (h) The cross-sectional area (A) required for peak flow (Q p) at a flow through velocity (V d): The cross-sectional area (A) is the width of the sump (W) multiplied by the depth of the sump (h): The sump can be sized using these equations: Where: Q p = design peak rate of flow V d = flow through velocity V s = settling velocity l = length of sump W = width of sump h = depth of sump V s is the settling velocity for a discrete particle using Stokes Law: Where: V s = settling velocities S s = specific gravity of particle γ = kinematic viscosity d = diameter of particle g = acceleration due to gravity Remember that the Reynolds number for flow must be less than one for Stokes Law to apply. DEP-WMD AH Volume I Design Aids Sediment Sump Design Calculations March 1, 2013 DA 3-1

14 Given the following, calculate the settling velocity, the flow through velocity and the sump dimensions: d = 0.01 cm sand particle S s = 2.65 for sand particle γ = 1.31 x 10-2 cm 2 /sec with water at 20 o C g = 981 cm/sec 2 V d is the flow through velocity which must be less than the velocity required to transport the design particle: = 0.26 Where: V d = velocity required to transport water born particle d = diameter of the particle = 0.01 cm = inches f = Darcy-Weisbach friction factor = 0.03 K = Cohesiveness factor of particle = 0.06 (clean grit = 0.04, sticky = 0.8) S s = Specific gravity of particle = 2.65 g = acceleration due to gravity = 32.2 ft/sec 2 To determine the sediment sump dimensions given the following: V d = 0.26 ft/sec l = (h V d)/v s V s = ft/sec Q p = 25 cfs w = Q p/(h V d) By fixing one of the variables (w, h, l), the others can be calculated: If h = 3.5 feet, then: A horizontal-flow sump or sediment basin must remove the particles under peak flow conditions. The length of the sediment sump or basin will be governed by the depth required by the settling velocity of the particle, and the cross-sectional area will be governed by the rate of flow. A length to depth ratio for the sediment sump or basin can be calculated: DEP-WMD AH Volume I Design Aids Sediment Sump Design Calculations March 1, 2013 DA 3-2

15 Flow through velocity (V) = length of sump (l) Settling velocity (Vs) depth of sump (h) The cross-sectional area (A) required for peak flow (Qp) at a flow through velocity (V): Qp = AV A = Qp/V The cross-sectional area (A) is the width of the sump (W) multiplied by the depth of the sump (h): A = Wh The sump can be sized using the these equations: Equation Equation l = Vd h Vs Qp = Vd Wh Where: Qp = design peak rate of flow Vd = flow through velocity Vs = settling velocity l = length of sump W = width of sump h = depth of sump Vs is the settling velocity for a discrete particle using Stoke s Law: Vs = (g/18) ((Ss 1)/v) d 2 Where: Vs = settling velocities Ss = specific gravity of particle v = kinematic viscosity d = diameter of particle g = acceleration due to gravity Remember that the Reynolds number for flow must be less than one for Stoke s Law to apply. Given the following, calculate the settling velocity, the flow through velocity and the sump dimensions: d = 0.01 cm sand particle Ss = 2.65 for sand particle v = 1.31 x 10-2 cm 2 /sec with water at 20 o C g = 981 cm/sec 2 Vs = (0.69 cm/sec) ( inch/cm) (1 ft/12 inches) = 0.23 ft/sec DEP-WMD AH Volume I Design Aids Sediment Sump Design Calculations March 1, 2013 DA 3-3

16 V is the flow through velocity which must be less than the velocity required to transport the design particle: = = 0.26 ft/sec Where: Vd = velocity required to transport water born particle d = diameter of the particle = 0.01 cm = inches f = Weesbach-Darcy friction factor = 0.03 K = Cohesiveness factor of particle = 0.06 (clean grit = 0.04, sticky = 0.8) Ss = Specific gravity of particle = 2.65 g = acceleration due to gravity = 32.2 ft/sec 2 To determine the sediment sump dimensions given the following: Vd = 0.26 ft/sec l = (h Vd)/Vs Vs = ft/sec Qp = 25 cfs w = Qp/(h Vd) By fixing one of the variables (w, h, l), the others can be calculated: If h = 3.5 feet, then: l = (h Vd)/Vs = (3.5 * 0.26)/ = ft w = Qp/ (h Vd) = 25/ (3.5 * 0.26) = ft DEP-WMD AH Volume I Design Aids Sediment Sump Design Calculations March 1, 2013 DA 3-4

17 DA 4 Critical Habitat Maps for Johnson s Seagrass Figure 1, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon north and south of the Sebastian Inlet Channel Figure 2, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon near the Ft. Pierce Inlet Figure 3, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon along the western shoreline of Hutchinson Island north of the St. Lucie Inlet Figure 4, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Hobe Sound along the western shoreline of Jupiter Island Figure 5, Critical Habitat for Johnson s seagrass (Halophila johnsonii) on the south side of Jupiter Inlet Figure 6, Critical Habitat for Johnson s seagrass (Halophila johnsonii) north of Bingham Island in central Lake Worth Lagoon Figure 7, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Lake Worth, near Boynton Inlet in Boynton Beach. Figure 8, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Lake Wyman in Boca Raton. Figure 9, Critical Habitat for Johnson s seagrass (Halophila johnsonii) within a portion of Biscayne Bay DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-1

18 Figure 1. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon north and south of the Sebastian Inlet Channel. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-2

19 Figure 2. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon near the Ft. Pierce Inlet. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-3

20 DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-4

21 Figure 3. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within the Indian River Lagoon along the western shoreline of Hutchinson Island north of the St. Lucie Inlet. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-5

22 Figure 4. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Hobe Sound along the western shoreline of Jupiter Island. Figure 5. Critical Habitat for Johnson s seagrass (Halophila johnsonii) on the south side of Jupiter Inlet. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-6

23 Figure 6. Critical Habitat for Johnson s seagrass (Halophila johnsonii) north of Bingham Island in central Lake Worth Lagoon. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-7

24 Figure 7. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Lake Worth, near Boynton Inlet in Boynton Beach. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-8

25 Figure 8. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within Lake Wyman in Boca Raton. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-9

26 Figure 9. Critical Habitat for Johnson s seagrass (Halophila johnsonii) within a portion of Biscayne Bay. DEP-WMD AH Volume I Design Aids Johnson s Seagrass March 1, 2013 DA 4-10

27 DA 5 Critical Habitat Maps for the Smalltooth Sawfish (As referenced in Section of Volume I) DEP-WMD AH Volume I Design Aids Smalltooth Sawfish March 1, 2013 DA 5-1

28 DA 6 HELPFUL INTERNET LINKS (Internet links are subject to change) The following Internet links are provided for additional information regarding: U.S. Army Corps of Engineers Regulatory Section (for information on Florida permits, public notices, regional general permits, nationwide permits, contact information, and the Source Book ) DEP-WMD AH Volume I Design Aids Helpful Internet Links March 1, 2013 DA 6-1