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The information required as part of a submittal under this standard will be shown graphically or provided as notes on a plan, as appropriate. The required information is in addition to the plan or plat requirements of the applicable process, such as, but not limited to, a plat, a development plan, a
plan, or a plot plan.
The regulated areas are listed below:
A. ERZ Watercourses
The regulated area for ERZ watercourses includes the 100-year floodplain for all watercourses. ERZ watercourses include:
1. Watercourses zoned as ERZ;
2. Watercourses that have been designated for preservation in the Tucson
Management Study and are delineated as proposed for ERZ designation or as under review for ERZ designation shall be considered as ERZ watercourses; or
3. The designated, proposed and under review watercourses are shown on the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site.
B. WASH Watercourses
The regulated area for WASH watercourses includes channel and banks of a watercourse and the area within 50 feet of the top of the bank, or where there is no defined bank, 50 feet from the ten-year flood boundary. WASH watercourses include:
1. Watercourses designated by name in the Watercourse Amenities, Safety and Habitat regulations in Article VIII of Chapter 29.
2. Watercourses that have been designated for preservation in the Tucson
Management Study and delineated as proposed for WASH designation or as under review for WASH designation shall be considered as WASH designated watercourses.
3. The designated, proposed and under review watercourses are shown on the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site.
4. The regulated area for watercourses under this technical standard 4-02.2.2.B.2 and 3 above shall not extend beyond the 100-year floodplain.
C. Regulatory Floodplain Watercourses
Within floodplains that are not designated as an ERZ or WASH watercourses in accordance with Sections 4-02.2.2.A or B above, the regulated area is the area within the 100-year floodplain for watercourses with flows of 100 cfs or more including, by not limited to, those areas which contain any of the following:
1. Hydroriparian, Mesoriparian, or Xeroriparian Types A, B or C habitats as delineated by Pima County as part of Article X of the Pima County Floodplain and
Hazard Ordinance.
2. Hydroriparian, Mesoriparian, or Xeroriparian High or Xeroriparian Intermediate Habitats as delineated in the TSMS Phase II
Master Plan.
3. Xeroriparian Low Habitats as delineated in the TSMS Phase II
Master Plan or Type D habitat as delineated by Pima County for connectivity between higher habitat classes, if low-volume, high-value habitats are present, including tabosa swales or similar habitats.
4. Unclassified or undocumented riparian habitat of equivalent value to the above criteria.
The protected riparian area is the area that has riparian habitat that is to be preserved. Except for watercourses designated by ordinance as subject to ERZ and WASH regulations, the protected riparian area shall not exceed the 100-year floodplain. protected riparian areas include areas that provide habitat structure, wildlife food and shelter, and that also aid in supporting wildlife connectivity,
control and help to improve
quality. Riparian habitat may include the vegetative resources, mapped areas and wildlife habitat and corridors listed below where such habitat is riparian in nature and function.
A. Vegetative Resources
Vegetative Resources are groups of three or more individual plants in close proximity to each other representing any of the plant species (and any combination of associated vegetative structure) listed below.
1. Mesoriparian plant species, including Arizona walnut, Fremont cottonwood, Goodding (black) willow, Arizona sycamore, Arizona ash.
2. Over-story vegetation consisting of closely spaced, perennial, woody (e.g., mesquite, foothill palo verde, Mexican palo verde, ironwood, netleaf hackberry), that are generally six feet or more in total height, and where the distance between canopy margins of individuals of the predominant over-story plant species is less than two times the height of the tallest individuals.
3. Understory vegetation consisting of closely spaced, perennial woody plants (e.g., catclaw and whitethorn acacia) that are generally six feet in total height, or less, and where the distance between canopy margins of individuals of the predominant understory plant species is generally less than two times the height of the tallest individuals, excluding nearly pure stands of understory vegetation consisting of the following perennial woody plants: burrow bush, creosote bush, desert broom, or triangle-leaf bursage.
4. Combinations of overstory and understory vegetation that together constitute valuable habitat, and tobasa swales.
B. Mapped Areas shown on the Critical and Sensitive Wildlife Habitat Maps which contain:
1. Major segments of desert riparian habitat extending from public preserves;
2. Major segments of desert riparian habitat not extending directly from a public preserve but containing a high density and diversity of plant and animal species;
3. Deciduous riparian woodlands;
4. Mesquite bosques; and,
5. Lakes, ponds, or wetlands.
C. Wildlife includes, but is not limited to, the wildlife and areas identified in the public draft or final City of Tucson Habitat Conservation Plan applicable to the regulated area.
All tentative plats,
plans, plot plans or other plans providing for
of development within property that includes any regulated area as defined in Section 4-02.2.2.A, ERZ Watercourses, shall identify and delineate the regulated areas and the protected riparian area on the property and shall comply with this standard. The boundary of the regulated area and the protected riparian area should be clearly depicted on applicable submittal documents.
The intent of this Technical standard is to preserve natural and existing drainage and 100% of the habitat areas within the protected riparian areas. To accomplish this, the regulations provide for two options: (1) no encroachment into the regulated area or (2) if encroachment is proposed into the regulated area, submittal of an environmental resource report in conformance with this section, and, if encroachment is proposed into the protected riparian areas, development in conformance with development restrictions and mitigation requirements in this section.
A. No Encroachment in Regulated Areas
For projects where there will be no encroachment within the regulated areas, development is not restricted by this section except as provided herein and except that the regulated areas shall be identified on the
plan, plat or development plan in a surveyable manner. This plan, or a separate plan, shall also indicate the proposed location of the temporary fencing which is required to protect the protected riparian areas during construction. The conditions for development with no encroachment are as follows:
1. ERZ Watercourses. Applications within the ERZ watercourses described in Section 4-02.2.2.A, ERZ Watercourses, above that propose a project with no encroachment into the regulated area are required to indicate the 100-year floodplain on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
2. WASH Watercourses. Applications for WASH watercourses as described in Section 4-02.2.2.B, WASH Watercourses, above that propose a project with no encroachment into the regulated area, are required to indicate the top of bank or ten-year flood boundary and the 50-foot study area beyond those lines on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
3. Regulatory Floodplain Watercourses. Applications within the regulatory floodplain watercourses described in Section 4-02.2.2.C, Regulatory Floodplain Watercourses, above that propose a project with no encroachment into the regulated area are required to indicate the 100-year floodplain on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
4. Floodplain Restoration. Revegetation, restoration or enhancement under this subsection shall not constitute “encroachment” under applicable codes. A Floodplain Restoration Plan must be prepared and approved in conformance with this subsection in order to undertake floodplain revegetation, restoration or enhancement. For areas within the regulated areas that are to remain as open space after development, revegetation and restoration of the open spaces areas is encouraged, but not required, to enhance the riparian resources within the regulated area as follows:
a. Voluntary revegetation, restoration or enhancement should create or restore the riparian habitat through the planting of native trees, shrubs, and understory species and the distribution of seed mix native to the
or a comparable reference
to the extent possible. Additional native species may be used in the restoration effort if they are typical of intact riparian habitat in areas similar to the
.
b. Revegetation, restoration or enhancement efforts should include native plant material salvaged from the
or preserved in place.
c. Development and revegetation, restoration or enhancement efforts shall conform to the city’s policies regarding
.
B. Encroachment in Regulated Areas
If the project proposes encroachment within the regulated areas, it shall conform to the following.
1. Environmental Resource Report. Applicants are required to submit an Environmental Resource Report as defined in Section 11.4.6 of the UDC. The supporting material for preparation of the Environmental Resource Report is based on information from the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site: The Critical and Sensitive Wildlife Habitat Map and Report, the Mayor and Council Interim Watercourse Improvement Policy and subsequent adopted policies, the Tucson
Management Study, the following Basin Management Plans: 1) West Branch, Santa Cruz; 2) Houghton East; 3) Este Wash; and 4) Arroyo Chico. the Tucson
Management Study, Phase II and field observation. An application may request that an element listed below be waived or that the report address only a specified area where a full report is not applicable to the proposed encroachment. DSD may grant such waivers where the elements or full report are not required by code. The Environmental Resource Report must include:
a. A table of contents, indicating all information by page or map number;
b. The location of the 100-year floodplain on, adjacent to, and a minimum of 200 feet upstream and downstream of the proposed development;
c. Soil conditions in and adjacent to the watercourse, and the
potential;
d. Existing rights-of-way or easement dedication along the wash for a distance of 500 feet upstream and downstream of the proposed development;
e. The existing and proposed ownership of any drainageway facilities on or adjacent to the
and identification of the persons responsible for the maintenance of such facilities;
f. Previous hydraulic/hydrology studies or maps prepared for the watershed and relevant floodplain studies, delineations, LOMR applications and approvals affecting the project
;
g. Groundwater recharge potential at this location;
h. Sediment transport characteristics along the watercourse centered on this location;
i. Existing and proposed utilities to and across the
;
j. Any other elements that may be characteristic of the watercourses on or adjacent to the
;
k. A map indicating the boundaries of the proposed development and its relationship to any watercourses designated on the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site;
l. An aerial photograph no more than two years old, with flight date, north arrow, project
boundaries, floodplain delineation, protected riparian area and a scale no smaller than one inch equals 200 feet. DSD staff may request an aerial photograph with topographic information;
m. Ground
photographs from points identified on submitted plans that document the protected riparian area and any areas within the protected riparian area to be disturbed;
n. Any applicable Basin Management Plan, which recommends that watercourses remain in a natural state, shall be referenced in the Report;
o. A map identifying the type, location and extent of all riparian resources and plant associations, including but not limited to, hydroriparian habitat, mesoriparian habitat, xeroriparian habitat, tobosa grass habitat, mesquite bosques, individual cacti and trees with a caliper of four inches or greater, and all saguaros, regardless of size. The identification of riparian habitat shall cover the entire
and is not limited to the regulated areas;
p. Delineation of the proposed protected riparian area and a statement of the total area of the
, the total area of the protected riparian area, the area within the regulated area, and the total of any areas proposed to be disturbed within the protected riparian areas;
q. Delineation of the riparian resources and any proposed open space linkages or facilities recommended by parks, recreation, open space, and trails plan, for a distance of 500 feet or one-half times the length of the watercourses on the property, whichever is greater, both upstream and downstream from the property. This shall be based on information that is available from aerial photographs, the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site and other public sources;
r. A Plant Inventory and aerial photographs of individual woody plants and cacti rooted within the encroachment area. Both living and dead plants and cacti should be inventoried. The Plant Inventory List shall include an identification number, genus and species, and size of all plants having basal trunk diameters greater than two inches. All plants inventoried are to be shown on an aerial photograph at a minimum scale of one inch equals 60 feet;
s. A delineation, map and assessment on an aerial photograph of habitat types noted on the Critical and Sensitive Wildlife Habitat Map;
t. A written or mapped assessment of significant densities of wildlife by species;
u. A description of the impact of the encroachment on riparian resources within the property and on the adjacent property as identified in subsection q above;
v. A written statement from the regional office of the Arizona Game and Fish Department regarding any impacts to fish and wildlife;
w. A draft Mitigation Plan in conformance with subsection 3 below if development is proposed within the protected riparian areas; and,
x. Other landscaping requirements established in Chapter 23 of the Tucson Code.
2. Development Restrictions. All development within the protected riparian area shall be reviewed to insure that there is no unnecessary disturbance of the riparian resources. Development that is outside of the protected riparian area but within the regulated area is not subject to this subsection. Necessary development shall include only the crossing of riparian habitats with roadways, bikeways, paved walkways and utilities as listed below where there is no viable alternate crossing available and the crossing is necessary for the reasonable development of the property. A written explanation as to why the development is necessary shall be submitted with the appropriate plans. Development that is permitted as necessary is subject to the following conditions:
a. Roadway, bike path, and paved walkway improvements and utility encroachments will cross the riparian habitat areas, not to run parallel to the protected riparian areas;
b. Encroachments that cross the protected riparian area shall be located and constructed to minimize disturbance of the habitat and wildlife movement;
c. All utilities in protected riparian area areas will be located underground; utilities will be placed either in proposed or existing public right of way along roadway, bike path, or paved walkway improvements or within approved easements.
d. Any roadway, bike path, or paved walkway improvement must be constructed in such a manner as to provide means for safe and accessible passage for wildlife.
e. Concrete, rock veneer and soil cement bank treatment for the culvert and associated drainage may be permitted within the public right of way upon
of the City Manager.
f. For WASH watercourses, concrete, rock veneer and soil cement bank treatment for the culvert that is outside of the proposed or existing public right of way shall be permitted only with the
of the Mayor and Council. For all other watercourses, concrete, rock veneer and soil cement should not be used where there is any practicable alternative.
g. Where a roadway, paved walkway, or bike path improvement or utility encroachment occurs within the protected riparian area, mitigation in conformance with Section 4-02.2.5.B.3, Mitigation Plans, shall be provided.
h. Temporary Fencing Required. No
,
, or construction will occur on a project
which includes areas designated as protected riparian area to be retained in a natural state until those designated areas are temporarily fenced. The temporary fencing shall remain in place during all phases of construction that could affect the protected riparian area.
3. Mitigation Plan. Where any development, except planting solely for revegetation, restoration or enhancement with an approved Floodplain Restoration Plan, encroaches within the protected riparian areas, mitigation will be required. A mitigation report shall be submitted with the Environmental Resource Report demonstrating that the proposed mitigation is in conformance with this subsection and applicable codes.
a. Mitigation Plans shall address the following:
1. Revegetation should recreate the lost functions and values of the riparian habitat through the planting of native trees, shrubs, understory plants and seed mix native to the
which will result in comparable habitat that is equal to the predisturbance habitat in area, plant density, diversity, and volume on the net
. Revegetation should be conducted over a sufficient area to accomplish the following mitigation ratios while accomplishing the specified plant density, diversity and volume of the impacted area.
i. Trees with basal trunk diameters ranging from two to four inches and shrubs should be replaced at a two to one ratio.
ii. Trees with basal trunk diameters larger than four inches should be replaced at a three to one ratio.
iii. Cacti, except cholla or prickly pear, should be replaced at a two to one ratio.
iv. Cottonwood, willow, walnut, sycamore, arizona ash, ironwood and canyon hackberry (Celtis reticulata) should not be removed. If removal is unavoidable and no other practicable alternative exists, then these plants shall be replaced by large, boxed trees at a three to one ratio and provided with at least three years of supplemental irrigation and care to ensure healthy establishment. Replacement trees shall be in 36-inch boxes and shall be at least eight to ten feet tall and at least two and one-half inches in diameter, measured three feet above the ground.
2. Mitigation can be designed to provide native riparian habitat that is appropriate for the location and soil conditions, even where that may be enhanced beyond the predisturbance habitat in terms of native habitat area, plant density, diversity and volume on the net
.
3. Revegetation should include native plant material salvaged from the
.
4. Development and revegetation shall conform to the city’s policies regarding
.
b. Mitigation Plans shall include:
1. A development plan/
plan, including landscape plans, indicating proposed development; floodplain encroachment locations; location of mitigation areas; techniques used for mitigating impacts to, or preservation of, natural areas; specifications for restoration and revegetation of disturbed areas; and general compliance with the applicable standards;
2. Landscape plans that document compliance with the mitigation plan requirements. A summary of mitigation and preservation requirements shall be included on the plans; and,
3. A description of the maintenance program that provides for revegetated/restored or enhanced areas. The program shall include irrigation to establish native plants, provide for regular inspection, removal of invasive species, and native plant replacement as necessary to successfully establish the mitigation habitat. All mitigation plantings and related improvements shall be maintained for at least three years following installation.
Ownership of the protected riparian area shall be provided in one or more of the methods set forth below to insure continued preservation of the area. Forms of ownership of protected riparian areas include:
A. protected riparian area Areas for proposed subdivisions may be either publicly owned, owned by a common association, or owned by a non-profit association which provides for conservation management.
B. Privately owned individual residential lots of 24,000 square feet or less may include protected riparian area where (i) there is a conservation easement prohibiting private development within the protected riparian areas, (ii) no more than 10% of the total area of the protected riparian area is included within individual private lots and (iii) no walls or fences are constructed within the protected riparian areas. The common ownership and the location of any portion of the protected riparian area within individual lots and applicable legal restrictions shall be included in a note on the final plat or development plan.
C. Privately owned individual residential lots that are greater than 24,000 square feet may include protected riparian area where (i) the protected riparian area is delineated on the plat providing a surveyed description of the location within each lot, and (ii) there is a note on the plat requiring that each purchaser of a lot shall sign a disclosure form acknowledging the prohibition upon development in the protected riparian area and (iii) no walls or fences are constructed within the protected riparian areas.
D. Where the protected riparian area is on property that remains under the ownership of a single person or entity following the development, the protected riparian area shall be protected through a conservation or public easement or other legal restriction upon further development.
All development within regulated areas must comply with all other applicable code provisions, including obtaining floodplain use permits where necessary. Washes zoned as ERZ washes or named in the WASH regulations are reviewed in accordance with Section 3.3.3, PDSD Director
Procedure.
Applications for review of projects affected by this technical standard shall be submitted to the
Section at PDSD. Review staff will evaluate submitted information for completeness and shall accept or reject the application within five days of the date of submittal. The applicant will be notified if the application is found to be incomplete.
Plans are reviewed for compliance with this standard in accordance with Section 3.3.3, PDSD Director
Procedure.
Development which encroaches within the protected riparian areas, except for development limited to revegetation or restoration in accordance with an approved Floodplain Restoration Plan, shall be reviewed by the Advisory Committee (SAC) as follows:
A. All watercourses subject to adopted ERZ or WASH regulations are reviewed by SAC as part of Section 3.3.3, PDSD Director
Procedure.
B. All watercourses designated to be treated consistent with the ERZ or WASH regulations under this technical standard and regulatory floodplain watercourses may be reviewed by SAC upon either the request of the applicant or upon the determination by the PDSD Director that such review is appropriate.
C. Review by SAC shall focus upon whether the application correctly defines, delineates and describes the protected riparian area and complies with Section 4-02.2.5.B.2 and 3, Development Restrictions and Mitigation Plan, respectively.
4.1 A minor encroachment modification may be requested for necessary development in addition to the roadway, bike path, paved trail and utility improvements as provided in Technical Standard 4-02.2.5.B.2 above. A minor encroachment under this subsection shall be approved if the loss of riparian resources does not impair the function of the habitat and the mitigation provides riparian resources of greater value if the request is granted. A modification under this subsection shall not exceed 5% of the total area of the protected riparian area on the . The mitigation shall be provided on a three to one ratio of new habitat for disturbed habitat. The mitigation shall be within the protected riparian area or an area that directly connects with the protected riparian areas. The mitigation shall be integrated with, and function as a part of, the protected riparian areas. The requirements for the Environmental Resource Report may be modified by PDSD staff as may be appropriate to document a minor encroachment under this subsection.
Due to the size and nature of this manual, it is unable to be accommodated within the Technical Standards Manual. The manual is available online as the Pima County Regional Flood Control District Design Standards for Stormwater Detention and Retention, June 2014 version (Last Revised February 2015).
City of Tucson Amendments to the Pima County Regional Flood Control District Design Standards for Stormwater Detention and Retention, June 2014 version (Last Revised February 2015)
Section 1.1 Purpose
The following paragraph;
1. Require first-flush retention that should be located throughout the development. The retained volume may also be used to meet all or part of the project's detention volume requirement;
Revise to read;
1. Require first-flush retention that may be located throughout the development. The retained volume may also be used to meet part of the project's detention volume requirement;
Section 1.2 Ordinance Overview and Detention Requirements
Section 1.2.2
The following paragraph;
b. New Development located within a Critical Basin must provide a sufficient combination of retention and detention to reduce the post-develop 2-,10-, and 100- year peak discharge rates to 90% of the pre-developed peak discharge rates. Other reductions may be specified by the Floodplain Administrator
Revise to read;
b. New Development located within a Critical Basin must provide a sufficient combination of retention and detention to reduce the post-develop 2-,10-, and 100- year peak discharge rates to 85% of the pre-developed peak discharge rates. Other reductions may be specified by the Floodplain Administrator
Add the following paragraph;
c. Properties within the City of Tucson that are currently in undesignated basins, shall be treated as balanced basins
Section 2.4.1 Stormwater Harvesting Basins
The following paragraph;
The maximum effective retention depth is 9 inches. If the basin is sloped, the depressed area may contain internal berms or check dams to pond water in multiple cells with planting areas on the upstream side of the berm. Each cell shall not retain greater than 9 inches of water.
Revise to read;
Without infiltration testing the maximum depth of retention in detention basins is 9 inches. If the basin is sloped, the depressed area may contain internal berms or check dams to pond water in multiple cells with planting areas on the upstream side of the berm. Retention depths greater than 9" require infiltration testing to verify that the draw down time is in accordance with section 4.5
Section 2.5 Retention within Detention Basins
The following paragraph;
Detention basins with uniform side slopes and no terraces may incorporate retention for a maximum depth of 9" below the lowest outlet elevation. The volume provided below the outlet can be counted as retention volume.
Revise to read;
Detention basins with uniform side slopes and no terraces may incorporate retention for a maximum depth of 9 inches below the lowest outlet elevation. The volume provided below the outlet can be counted as retention volume. If infiltration testing is provided, the retained depth may be increased.
The following paragraph
Terraces may be proposed within a detention basin in order to meet riparian habitat or native plant requirements. When vegetated terraces and bioretention areas are proposed, the maximum retention depth may be increase to 18 inches. Section 5.8 contains standards for retention within detention basins.
Revise to read;
Terraces may be proposed within a detention/retention basin in order to meet riparian habitat or native plant requirements Section 5.8 contains standards for retention within detention basins.
Section 3.1 Peak Discharge Rate Reduction Requirements
The following paragraph;
Within a Critical Basin, post-developed peak discharge rates shall not exceed 90% of pre-developed peak discharge rates at the project boundary, unless a different percentage is specified by the Floodplain Administrator.
Revise to read;
Within a Critical Basin, post-developed peak discharge rates shall not exceed 85% of pre- developed peak discharge rates at the project boundary, unless a different percentage is specified by the Floodplain Administrator.
Section 3.2.1 Pre- Developed Conditions
The following paragraph;
The pre-developed conditions peak discharge rates for each return period (Qpre -rp) shall be established using the modeling methods described in the District's Technical Policy, TECH-015, Acceptable Methods for Determining Peak Discharges, and Technical Policy, TECH-018, Acceptable Model Parameterization for Determining Peak Discharges, and any other technical policies as specified by the Floodplain Administrator. The District's Technical Policies are available through the Rules and Procedures page of the District's web page.
Revise to read;
The pre-developed conditions peak discharge rates for each return period (Qpre -rp) may be established using the City of Tucson STANDARDS MANUAL FOR DRAINAGE DESIGN AND FLOODPLAIN MANAGEMENT, modeling methods described in the District's Technical Policy, TECH-015, Acceptable Methods for Determining Peak Discharges, and Technical Policy, TECH-018, Acceptable Model Parameterization for Determining Peak Discharges, and any other technical policies as specified by the Floodplain Administrator. The District's Technical Policies are available through the Rules and Procedures page of the District's web page.
Section 4.9.1 Outlet Structure Standards
Add the following as paragraph 8.
8. A bleed pipe or other outlet may be added to the basin provided that its discharge rate and invert elevation meets the requirements of section 9. Unless a waiver has been granted per Section 9, the bleed pipe shall be capped and for maintenance purposes only.
Section 4.13.2 Underground Storage Prohibitions
The following paragraph;
3. Providing first flush retention underground is prohibited
Revise to read;
3. Providing first flush retention underground is prohibited, without prior approval of the Floodplain Administrator
Section 5.8 Retention within a Detention Basin
The following paragraph;
3. A maximum of 9 inches of retention is allowed, unless designed as describe below. The depth is measured from the lowest elevation on the basin floor to the lowest outlet invert elevation
a. The retention depth of up to 18 inches may be allowed if the following conditions are met. See Figure 5.5
Revise to read;
3. A maximum of 9 inches of retention is allowed, unless designed as described below. The depth is measured from the lowest elevation on the basin floor to the lowest outlet invert elevation
a. A retention depth of greater than 9 inches may be allowed if the following conditions are met. See Figure 5.5
The following paragraph;
iv. The remaining 50% of the basin area may be constructed so that the maximum retention depth is 18 inches. This area shall meet the construction requirements of part 1 of this Section.
Revise to read;
iv. The remaining 50% of the basin shall meet the construction requirements of Part 1 of this section
Section 9 DETENTION WAIVER REQUEST AND PAYMENT OF IN-LIEU FEE
The following section Title;
Section 9 DETENTION WAIVER REQUEST AND PAYMENT OF IN-LIEU FEE
Revise to read;
Section 9 DETENTION/RETENTION WAIVER REQUEST AND PAYMENT OF IN-LIEU FEE
Add the following as the first paragraph;
A waiver for retention may be requested for situations where the volume of retention cannot be contained within the development property or where tests show that the soils have poor infiltration. The waiver may request a reduction in retention volume or the transference of design consideration from retention to detention with a maximum discharge rate of 1-cfs for sites in critical basins or 3-cfs for sites in balanced basins. These maximum discharge rates may be achieved by using a bleed pipe or weir in which the invert of the bleed pipe or weir is a maximum of 6 inches above the basin floor. The waiver may be granted by the engineering reviewer as part of the development review process. The approved waiver request will be included in the Drainage Report or Drainage Statement for the project.
Section 11.2.2 General and Permitting Notes
The following paragraphs;
3. When a project has drainage and grading improvements that are required to mitigate off-site adverse impacts to the proposed development, an As-Built Certification or plan shall be prepared and submitted to the Floodplain Administrator. The As-Built Certification or plan requires approval prior to the issuance of any building permits, except for model home permits and any permits necessary to build drainage infrastructure.
Provide the following Permitting Note to disclose this requirement:
"Prior to issuance of any building permits an As-Built Certification (Plan) of the drainage and grading improvements that are required to mitigate off-site adverse impacts to the project shall be prepared and submitted to the Floodplain Administrator. Upon approval of the as-built plan by the Floodplain Administrator, the hold to issuance of building permits can be removed."
Revise to read;
3. When a project has drainage and grading improvements that are required to mitigate off-site adverse impacts to the proposed development, an As-Built Certification or plan shall be prepared and submitted to the Floodplain Administrator.
Provide the following Permitting Note to disclose this requirement:
"An As-Built Certification (Plan) of the drainage and grading improvements that are required to mitigate off-site adverse impacts to the project shall be prepared and submitted to the Floodplain Administrator."
(Am. Res. 23289, 1/5/2021)
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