§ 6.05.03. Stormwater Plans for Single-Family Dwelling Units, Two-Family Dwelling Units, and Duplexes

A.

Purpose. The purpose of this section is to manage stormwater runoff on lots with single-family dwelling units, two-family dwelling units , or duplexes in order to prevent detrimental impacts on site or to adjacent properties. This section is also designed to provide criteria for demonstrating compliance with Collier County Code of Laws and Ordinances section 90-41(f)(8). For the purposes of this section, the term impervious area shall include roofed buildings , concrete and asphalt pads, cool deck (e.g. spraycrete), pavers with limerock base, swimming pools, and lined pond area. Additionally, the term pervious area shall include grass, crushed stone (e.g. #57), mulch, pavers without limerock base, and unlined pond area.

B.

Applicability. A Type I or Type II Stormwater Plan shall be required for lots with single-family dwellings, two-family dwellings , or duplexes with the following exceptions:

1.

Lots located in the Rural Agricultural (A) zoning district outside the Immokalee Urban Area Overlay district and outside the coastal urban designated area as established in the Future Land Use Map.

2.

Lots that have received a Surface Water Management or Environmental Resource Protection permit from the South Florida Water Management District.

C.

Stormwater plan submittal. A stormwater plan shall be submitted as part of an application for a building permit for any of the following:

1.

Type I Stormwater Plans.

a.

New structures , additions, pools, or decks on lots with 40 percent or less impervious area , or as described in the following zoning districts:

i.

RSF-1 zoned lots with 30 percent or less impervious area .

ii.

Rural Agricultural (A) zoned lots within the Immokalee Urban Area Overlay district or within the coastal urban designated area as established in the Future Land Use Map with 30 percent or less impervious area .

iii.

Estates zoned lots with 25 percent or less impervious area .

b.

New structures , additions, pools, or decks on lots that discharge directly to a waterbody downstream of the last control structure, whether or not the lot exceeds the impervious area thresholds in LDC section 6.05.03 C.1.a above.

2.

Type II Stormwater Plans.

a.

New structures , additions, pools, or decks on lots with more than 40 percent impervious area , or as described in the following zoning districts:

i.

RSF-1 zoned lots with more than 30 percent impervious area .

ii.

Rural Agricultural (A) zoned lots within the Immokalee Urban Area Overlay district or within the coastal urban designated area as established in the Future Land Use Map with more than 30 percent impervious area .

iii.

Estates zoned lots with more than 25 percent impervious area .

b.

New structures , additions, pools, or decks on lots that discharge directly to a waterbody upstream of the last control structure, whether or not the lot exceeds the impervious area thresholds in LDC section 6.05.03 C.2.a above.

D.

Stormwater plan criteria.

1.

Type I Stormwater Plan. Type I Stormwater Plans shall be prepared by a Florida registered design professional, licensed contractor or owner builder. The Type I Stormwater Plan shall demonstrate the following:

a.

Stormwater runoff. Discharges from the impacted area shall be directed into one or more of the following:

i.

An existing surface water management system.

ii.

A drainage conveyance system, such as swales or underground storm sewer systems.

iii.

On-site retention or detention areas. The bottom of retention or detention areas shall be above the wet season water table.

iv.

A waterbody downstream of the last control structure. Stormwater discharges to a waterbody shall not result in erosion of soil. Discharges may be allowed through an orifice with a minimum size of 3 inches and the soil adjacent to the discharge area shall be stabilized. For lots discharging directly to waterbodies upstream of the last control structure, see LDC section 6.05.03 D.2.

b.

Design standards.

i.

Retaining walls shall be set back six inches from the property line, if applicable.

ii.

Stone in French drains shall be calculated with a 40 percent void ratio, if applicable.

iii.

Stormwater pipes, if used, shall not be metal.

iv.

Gutters and downspouts shall comply with LDC section 6.05.01 C, if applicable.

c.

The location, dimension, and setbacks of septic systems, if applicable.

2.

Type II Stormwater Plan. Type II Stormwater Plans shall be prepared by a professional engineer licensed in the state of Florida. The Type II Stormwater Plan shall demonstrate the following:

a.

Stormwater runoff. Discharges from the impacted area shall be directed into one or more of the following:

i.

An existing surface water management system.

ii.

A drainage conveyance system, such as swales or underground storm sewer systems.

iii.

On-site retention or detention areas. The bottom of retention or detention areas shall be above the wet season water table.

iv.

A waterbody. Stormwater discharges directly to a waterbody shall not result in erosion of soil. Discharges may be allowed through an orifice with a minimum size of 3 inches and the soil adjacent to the discharge area shall be stabilized.

b.

Design standards.

i.

Retaining walls shall be set back six inches from the property line, if applicable.

ii.

Stone in French drains shall be calculated with a 40 percent void ratio, if applicable.

iii.

Stormwater pipes, if used, shall not be metal.

iv.

Gutters and downspouts shall comply with LDC section 6.05.01 C, if applicable.

c.

The location, dimension, and setbacks of septic systems, if applicable.

d.

An engineer's analysis that demonstrates the following:

i.

Water quantity calculations by a qualified engineer or technician that demonstrate the ability to accommodate the runoff from the area exceeding the applicable threshold in LDC section 6.05.03 C from a 5-year 1-day storm.

ii.

A matrix of all required separation distances between wells, drainfield systems, and stormwater retention/detention areas. The calculations may be done on the site plan or may be in a separate engineer's report, but the site plan must be signed and sealed by a professional engineer licensed in the state of Florida.

e.

A certification of compliance shall be submitted to the County by the engineer prior to an inspection.

E.

Application submittal requirements. The Administrative Code shall establish the submittal requirements for stormwater plans.

F.

Inspection and maintenance.

1.

Inspection. The subject property shall be inspected by the County prior to issuance of a certificate of occupancy or certificate of completion, as applicable, for consistency with the approved stormwater plan.

2.

Maintenance. The property owner shall maintain site grading and drainage (e.g. swales, French drains, grates, etc.) in accordance with the approved stormwater plan. Future changes to impervious area or site grading shall not modify the site in a manner that will prevent continued drainage of the site as shown on the approved stormwater plan, whether or not a permit is required for an improvement.

G.

Violations. Where a violation of Collier County Code of Laws and Ordinances section 90-41(f)(8) has been found by the Code Enforcement Board or Special Magistrate, a stormwater plan shall be submitted that demonstrates the additional flow of surface water has been eliminated. The subject property shall be inspected by the County to determine if the violation has been resolved.

(Ord. No. 17-12, § 3.B)