In Tampa, Florida, plan reviewers demand that every aspect of residential on-site stormwater infiltration-permeable pavers, rain gardens, dry wells, and related features-be rendered with strict adherence to local drawing conventions, material specifications, and cited code sections. The approval of permit plans hinges not only on hydrologic performance, but also on how these features are drawn, dimensioned, and annotated on the submittal sheets, especially given the city's stormwater mitigation mandates and zoning nuances.

Drawing Conventions for On-Site Infiltration Features on Tampa Permit Plans

Lineweights, Symbols, and Site Sheet Organization

Permit-ready site and grading plans for residential projects in Tampa are expected to follow a professional, consistent convention for communicating on-site infiltration features to reviewers and field personnel. The City of Tampa’s digital plan review workflow (see Digital Plan Review Help Center) reinforces the importance of clarity in site feature differentiation, especially in electronically submitted PDFs.

  • Property lines: The heaviest solid lineweight (e.g., 0.70mm) or a long-dash-double-short-dash pattern, immediately legible to distinguish site boundaries.
  • Setback lines: Heavy dashed (approx. 0.50mm), essential for showing the separation required between infilatration features and property limits, per City of Tampa setback codes.
  • Easements: Medium dashed (long-dash-short-dash, ~0.35mm) to indicate restricted zones, especially important when dry wells or rain gardens approach utility easements.
  • Building footprints: Solid, 0.50-0.70mm; the reference for dimensioning all infiltration features.
  • Dimension and leader lines: The thinnest available (0.13-0.25mm), with ticks or arrows, to avoid visual clutter and facilitate plan review markup.

Proposed infiltration features are clearly differentiated from existing site elements-proposed permeable walkways or rain gardens must be rendered with distinctive hatch patterns or shading for rapid identification during review (see innowave-studio.com).

Symbols and Annotations for Infiltration Features

Clarity during both review and construction mandates unambiguous symbols and a comprehensive plan legend. For Tampa:

  • Permeable pavers: Indicated by a polyhedral hatch denoting open joints and drainage voids.
  • Rain gardens/bioinfiltration: Gentle contour lines, distinctive low vegetation symbols, and a hatched "ponding area" outline, usually annotated as "Rain Garden / Bioinfiltration Basin."
  • Dry wells: Circular plan symbol, cross-hatched interior, call-out as "DRY WELL (SEE DETAIL XX)" linked to a section on the detail sheet.

City of Tampa reviewers often redline plans for “Legend missing infiltration symbols,” “Proposed drywell not dimensioned from nearest structure,” or “Rain garden not clearly distinguished from adjacent landscaping.” Standardization is supported by national symbol conventions (archtoolbox.com).

Annotation, Dimensioning, and Sheet Flow Organization

Annotations are directly correlated to both construction outcome and code compliance.

  • Dimensions: All infiltration features must be dimensioned to property lines, building corners, adjacent grade breaks, and, if applicable, existing onsite trees or utilities. For example: “Dry well, 12’-6” from southwest corner of structure, 4'-0" from property line (min per setback)”.
  • Material callouts: Require detail numbers and relevant specs, e.g., “2.5” permeable paver over ASTM #57 aggregate, see Section Detail B” or “Rain garden with 6” ponding depth, 18” engineered soil, per Section C”.
  • Elevations: Existing and proposed spot elevations must be provided to demonstrate positive drainage and adequate cover. Elevation callouts often trigger redlines such as “Proposed rain garden invert conflicts with existing swale flow line.”

Plan set organization typically includes a cover sheet (project info, code references, sheet index), a site (layout) plan (all stormwater features), and a grading/drainage plan (existing and finish grades, flow arrows, storm runout).

Common Redlines and Reviewer Expectations

  • “Inconsistent elevation callouts between sheets.”
  • “Dimension to neighboring property missing for dry well.”
  • “Proposed infiltration trench not shown on all relevant sheets.”

Addressing these preemptively by cross-coordinating annotation, employing a robust symbol legend, and verifying congruence between site and detail plans expedites approvals (kingswaydrafting.com).

Dimensioning and Specification Detail Examples

  • Permeable Pavers: Typically called out as “4"x8"x2.5” concrete unit pavers over 1-1.5" bedding sand, 6" ASTM #57 open-graded aggregate, min 90% compaction, infiltration rate min 100 in/hr.”
  • Rain Gardens: "Minimum 30 square feet area with 6" ponding depth, 24” deep engineered filter media mix (60% sand, 20% topsoil, 20% compost), native plant list per plan legend."
  • Dry Wells: "4’ diameter x 3’ deep, precast perforated concrete, 12” washed stone backfill, non-woven geotextile wrapped."

In all cases, refer to "Stormwater detail per City of Tampa Stormwater Standard Details," as requested by plan reviewers (Stormwater Standard Details).

Critical Dimensioning and Material Specifications on Tampa Infiltration Drawings

Code-Driven Sizing and Siting

Residential stormwater infiltration in Tampa is governed by the 2023 Florida Building Code (FBC) Residential and the City of Tampa Stormwater Technical Standards Manual. Details for each system are tailored for local sandy soils, high-water-table risks, and tropical rainfall regimes.

  • Impervious Surface Limit: Tampa code mandates that “for single-family lots where total impervious area exceeds 50% of lot size (pool excluded), the first 0.5 in. of rainfall from impervious areas must be retained and infiltrated onsite” (Stormwater Tech Standards Manual).
  • Volume calculation trigger: On projects exceeding thresholds, permit reviewers regularly require full on-site retention calculations, dimensioned details, and cross-checked locations for rain gardens or dry wells versus required setbacks and side yards.

Infiltration Media and Structural Details

  • Aggregate: For infiltration trenches/basins, “clean, washed, open-graded aggregate, 1.5-2.5 in. nominal” maximizes hydraulic storage, typical for drywell backfill or stone reservoirs below permeable pavers. Plan detail: cross-section with labeled aggregate depth and gradation.
  • Geotextile: Non-woven, needle-punched separation fabric “with minimum flow rate of 120 gallons/min/sq.ft., per ASTM D4491,” direct call-out on plan detail, prevents fines from clogging base aggregate.
  • Filter/Planting Media: Rain gardens: “60% sand / 20% topsoil / 20% compost (by volume), screened, with infiltration rate >2 in/hr.” Indicate layer depths and top-dressed mulch (2-3"). Field RFI: “Clarify if local soil amendments required for in-situ clay lenses.”

Plans must show:

  • Min. 2' vertical separation between bottom of infiltration device and seasonal high water table, per SWFWMD guidance.
  • Rain garden: 6"-12" ponding depth, overflow clearly notated, engineered soil beneath.
  • Dry wells: 4' diameter x 3' deep typical, perforations called out, surrounded by 12" gravel collar, geotextile wrap "SEE DETAIL A".

Critical Slope, Separation, and Depth Requirements

  • Maximum slope: Stabilized side slopes ≤3:1 (horizontal:vertical), as cited by Tampa’s Stormwater Technical Standards. Channels exceeding this risk reviewer redline: “Show compliance w/ max slope 3:1 for rain garden” (Plan check 2024-01945).
  • Dry wells: “Base of dry well min. 24" above seasonal high water table. Consult geotech report (call-out: 'SEE GEOTECH REPORT, PERMIT DOC. D')".

Distinct profiles for each feature are required on detail sheets: “Rain garden Section Detail C-show plan area, depth, soil layering, plant zones, overflow, and side slope dimensions.”

Plan-Reviewer Comments & Typical RFI Responses

  • “Provide soil percolation data and separation to high groundwater per SWFWMD standards.”
  • “Dimension storage volume in cubic feet, and show ponding depth. Overflow required to safe location at finish grade.”
  • “Geotextile spec not cited on detail-please add ASTM/D number.”

Systematic dimensioning and annotation eliminates most requests for information (RFIs) and streamlines permit rounds.

Integrating Code Compliance and Local Amendments into Permit Drawings

Zone-Specific Code References and Call-Outs

Tampa’s review staff expect direct code citations for stormwater features, especially with respect to zoning overlay districts and stormwater retention:

  • Florida Building Code (FBC) 2023: Cite applicable sections for unique structures. For any wall adjacent to infiltration elements, call-out “Retaining wall FBC Section 1807.4 design and construction compliance.”
  • City of Tampa Code of Ordinances Chapter 24: “All on-site infiltration features are designed and located per City of Tampa Code of Ordinances Chapter 24, Stormwater Management.”

Clear code cross-references not only clarify intent during plan review, but also confirm the drafter’s familiarity with the current regulatory framework (Tampa Suite of Codes).

Addressing Common Plan Review Redlines in Tampa Zoning Context

  • Impervious surface limits: Zoning districts RS-50, RS-60, RM-16, and RM-20 all carry defined ISR (Impermeable Surface Ratio) caps: e.g. “Proposed ISR: 0.50 (50%), complying with RS-50 maximum per City of Tampa Code §27-156(c), Table 4-2.” Redline triggers include “Missing ISR calculation,” “ISR exceeds allowed maximum for RS-50.”
  • Setbacks: Detail call-outs must reflect Table 4-2 requirements; “Rain garden: 20 ft rear setback, 7 ft side setback per RS-50 zoning.” Reviewer comments: “Dry well does not meet 7’ side yard setback.”
  • Overflow paths: The City requires positive overflow routes that safely bypass adjacent lots and structures. Annotation: “Rain garden designed per Ch. 24 Technical Standards to direct excess to public R/W via vegetated swale at finish grade.” Plan reviewers often note: “No overflow shown from rain garden in extreme event.”

Sheet Notations, Detail Call-Outs, and Redline Avoidance

  • Leader line structure: “SEE DETAIL B FOR MATERIAL THICKNESS & INFILTRATION RATE SPEC.”
  • Code note block: “All grading and drainage improvements conform to FBC Section 1807, City of Tampa Chapter 24, and SWFWMD ERP criteria.”

All sheets must be coordinated; plan reviewers redline “Site, landscape, and grading plans inconsistent for infiltration location.”

Materials, Dimensions, and Board-Adopted Standards

  • Retaining walls: “8” min. thickness, 3,000 psi concrete, #4 rebar @ 12” O.C. each way. Max. wall height 4’ unless engineered.”
  • Impervious areas: “4” concrete paver drive, 3” walkway, declare on material legend.”

Every call-out should be cross-referenced to City adopted details, ensuring field and review consistency.

Runoff Calculations and Volume Documentation on Permit Plan Sheets

Impervious Surface Calculations and Criteria

Hydrologic analysis for Tampa permit plans must show every step from first rainfall to final infiltration.

  • Impervious summaries: “Roof: 1,450 sq ft, Driveway: 600 sq ft, Walks: 150 sq ft, Total: 2,200 sq ft (44% lot coverage).” Table format on site plan, with “% of site: 44%.”
  • Design storm: All calculations based on “25-year, 24-hour rainfall event, per Tampa’s Stormwater Technical Standards Manual” (tampa.gov).

Reviewer checklist includes: “Retain 0.5” minimum on-site for first flush; show calculations for minimum required retention storage.”

Runoff Volume and Infiltration Sizing Calculations

Engineered residential plans integrate tables and narrative calculation summaries directly on drawing sheets, referencing supporting documents as needed.

  • Volume equation sample block:
    • Total impervious area: 2,200 sq ft x 0.04167 ft (0.5”/12) = 91.7 cu ft retention required.
    • Dry well: “Proposed storage: (π x 2’ radius x 3’ depth) = 37.7 cu ft per dry well; 3 wells total storage = 113 cu ft.” Call-out: “Meets required retention (see Calculation Summary, Sheet C-2).”

Reviewer redlines often state: “Retention volume undersized-recalculate for correct ISR,” or “Total infiltration area not correlated with geotechnical percolation data.”

Geotechnical Data and Infiltration Performance

  • Geotech report call-out: “Percolation rate = 4 in/hr @ 36” depth. Minimum 2’ clearance to SHWT.”
  • Section cross-reference: “Calculation assumes field-tested hydraulic conductivity from Geotech Report Section 5.2 (SEE ATTACHED).”
  • Reviewers expect a statement clarifying: “Infiltration design based on on-site percolation data, meeting City Stormwater Manual / SWFWMD requirements.”

Calculation Summary Format on Permit Sheets

SWFWMD and City of Tampa both encourage a "Calculation Summary Table" on the drawing or as a referenced appendix:

  • Impervious area per surface
  • ISR percent, required retention depth
  • Total required retention (cu ft)
  • Device volume (ea. - cu ft)
  • Total onsite storage provided
  • Geotech parameters used

Example (as shown on Sheet C-4 annotation): “Retention Calculation Table-Roof: 1,450 sq ft; Drive: 600 sq ft; Total: 2,050 sq ft; Required: 0.5” depth = 85.4 cu ft; Provided: 3 dry wells @ 32 cu ft = 96 cu ft.”

Reviewer-rejected sheets often lack a clear summary block: “Calculation block incomplete; geotech data not cited - please revise and resubmit.” City of Tampa reviewers frequently request that infiltration volume calculations reference both “onsite percolation data results” and “best available City rainfall depth tables.”

Sheet Notation for Compliance with FBC and Local Ordinances

  • FBC reference: “Stormwater system sized and located per FBC Ch. 11, City of Tampa adopted amendments, and Stormwater Technical Standards.”
  • Local amendment call-out: “Supplemental on-lot controls per Tampa Code §24-104, for single-family retention mandate.”

Post-Construction Maintenance and Construction Erosion Control Details

Required Site and Detail Sheet Elements for Tampa Residential Projects

Maintaining infiltration features-and controlling sediment during construction-is not optional. Tampa’s permitting and inspection process requires that access for maintenance, clean-outs, filter media replacement, and erosion and sediment controls be documented on permit sheets.

  • Access points: “Rain garden maintenance path: 30” width, mulch surfacing, min 1.5’ vertical clearance to canopy.” Call-out: “MAINTENANCE ACCESS SEE SECTION D.”
  • Clean-outs for dry wells: “4” PVC riser w/ screw cap at surface-label ‘DRY WELL CLEAN-OUT’.” Require on plan and in detail sheet, with note: “ACCESS FOR INSPECTION & SEDIMENT REMOVAL.”
  • Filter media replacement: “Top 3" mulch layer, replace annually, engineered filter media to be inspected every 3 years and replaced if infiltration rate drops below 1 in/hr.” Detail annotation: “SEE OWNER MAINTENANCE INSTRUCTIONS SHEET.”

Construction Erosion and Sediment Control (ESC) Measures-Required During Construction

Tampa’s Stormwater Technical Standards Manual, in conjunction with City Code Chapter 21, requires clear specification of temporary ESC elements. Key details include:

  • Gravel entrance/exit: “Stabilized construction entrance-min. 12’ wide x 50’ long, 2” DGA (dense-graded aggregate), geotextile underlayment. Call-out: ‘TEMPORARY ESC ENTRANCE SEE TSSM STANDARD 4.1’.”
  • Silt fences: “Silt fence to perimeter of disturbance, trenched 6” deep, supported every 6’, per City Standard 4.2.” Call-out: “INSTALL PRIOR TO DEMO. REMOVE WHEN PERMANENT VEGETATION ESTABLISHED.”
  • Inlet protection: “Block and gravel protection at all catch basins. Maintenance after 0.5” rain or visible sediment accumulation.”

Site plan must indicate each ESC location, keyed to the legend and detail sheet numbers for reviewer/field coordination (tampa.gov/erosion-control).

Plan-Review Redlines and Required Notations

  • “ESC not shown for driveway or site entrance.”
  • “Silt fence not continuous-add at lot rear boundary.”
  • “Add block and gravel inlet protection at downstream CB.”

All required ESC notes and typical details are referenced to Stormwater Technical Standards Manual Standard Details. Additional call-out: “Contractor to inspect all silt fences, entrances, and inlet protections after storm events or every 7 days.”

Post-Construction O&M and Maintenance Notation

  • Clean-out instructions: “Remove accumulated sediment from clean-out risers after each storm event exceeding 0.5”. Inspect condition of infiltration media annually.”
  • Filter media replacement: “If infiltration performance degrades (water remains 48+ hrs after storm), remove and replace top 12” filter media. See Maintenance Schedule.”
  • Access points: Clearly dimensioned on site and detail sheets, with notations referencing O&M manual/filed maintenance agreement, as required by permit conditions.

Reviewer redlines frequently read: “Maintenance access path not shown,” or “No method provided for drywell inspection; add clean-out riser per city detail.”

Conclusion

Residential stormwater infiltration features in Tampa, FL must be rendered on permit plans with an exacting attention to dimensioning, material specification, standardized notation, and code-integration-supported by calculations and post-construction maintenance details. Tampa’s permit system, layered City and State codes, and direct plan-review feedback create an environment where success is measured both by the accuracy of the engineered solution and the clarity of its presentation on drawings. By applying these conventions-referencing the FBC, City of Tampa Code, Stormwater Technical Standards, and integrating reviewer feedback-submittals can achieve rapid, compliant approval and smooth construction.

Kingsway Drafting & Design delivers precise, code-driven stormwater detailing for successful, buildable permit plans in Tampa and across Florida.