(a) No adverse impact. No single-family development of a lot shall be permitted that materially and adversely impacts storm water runoff or drainage on:
(1) The subject property or other properties; or
(2) On any storm water facility or system, as determined by the director of public works or designee, in his or her discretion, consistent with this article XII and customary engineering practices and the village's Engineering and Specifications Manual.
(b) Determination of compliance.
(1) A. In furtherance of the director of public work's or designee's determination pursuant to subsection 9-83(a), an applicant for single-family development of a lot shall submit detailed storm water plans and other engineering documentation, including without limitation a calculation of the C-Factor for the lot as proposed to be developed. For purposes of this subsection 9-83(b),
C-FACTOR is calculated using the following formula:
(.95 X Impervious Surface on a Lot) + (.5 X Pervious Surface on a Lot)
Total Lot Area
B. The determination of whether a particular surface is pervious or impervious (or the degree to which a surface may be calculated as pervious) shall be in the director of public work's or designee's discretion, consistent with customary engineering practices and the village's Engineering and Specifications Manual.
(2) Except as otherwise provided in subsection 9-83(b)(4), the director of public works or designee shall conclude that a proposed development complies with the general regulation set forth in subsection 9-83(a) if such development does not exceed the greater of the following subsections 9-83(b)(2)A. and B.:
A. The C-Factor set forth in the following table:
Lot Area | C-Factor |
i. Lots equal to or less than 10,000 sq. ft | .67 |
ii. Lots greater than 10,000 sq. ft. but not more than 20,000 sq. ft. | .65 |
iii. Lots greater than 20,000 sq. ft. | .62 |
or
B. The C-Factor existing on a lot that is developed with a single-family dwelling as of the effective date of this article XII of chapter 9, being August 16, 2007; provided, however, that this subsection 9-83(b)(2)B. shall not apply if the single-family dwelling is demolished, damaged or destroyed, by any means, to the extent of more than 50% of the cost of replacement.
(3) If the director determines that a lot does not meet the general regulation set forth in subsection 9-83(A) or the C-Factor standards set forth in subsection 9-83(b)(2), the owner may only proceed with the development of the lot if the owner installs and maintains an alternative engineered solution that is acceptable to the director of public works or designee, in his or her discretion and consistent with the following:
A. The proposed alternative engineered solution shall be designed to provide storm water detention for the lot in a manner that is equivalent to, or results in a lower offsite storm water impact than, the applicable C-Factor for the lot pursuant to subsection 9-83(b)(2)A. or B.;
B. Any proposed alternative engineered solution shall be designed consistent with customary engineering standards for storm water drainage and shall comply with the standards for acceptable alternative engineered solutions, as set forth in the village's Engineering and Specifications Manual. In addition, the alternative engineered solution shall be consistent with all village codes, ordinances, regulations and policies, including without limitation the purposes of the village's comprehensive plan, the village's tree preservation ordinance contained in article II of chapter 34 of this code, and the village's grading regulations contained in article XIV of this chapter 9; and
C. The alternative engineered solution shall be designed, constructed and maintained at all times in a safe condition to protect persons and property from injury and damage.
(4) If the director determines that exceptional circumstances exist on or in connection with a lot, its development, or its environs that result or will likely result in a material and adverse storm water runoff or drainage effects notwithstanding the satisfaction of the C-Factor standards set forth in subsection 9-83(b)(2), then the owner of such lot may be required to install and maintain an alternative engineered solution in connection with the development of such lot. The nature and extent of such alternative engineered solution shall be determined by the director in the manner provided in subsection 9-83(b)(3).
(5) Prior to any certificate of occupancy being issued for a lot for which an alternative engineered solution has been required pursuant to subsection 9-83(b)(3) or subsection 9-83(b)(4), the owner shall execute and record a declaration of covenants and restrictions to ensure maintenance and preservation of such alternative engineered solution, which declaration shall be subject to the review and approval of the village attorney. The declaration shall provide that the ownership and maintenance of the alternative engineered solution shall be the responsibility of the owner. The declaration shall further provide the village with the right, but not the obligation, to inspect and, if necessary, repair, replace, maintain, or otherwise care for the alternative engineered solution, and the village shall have the right to assess its costs in connection with any such actions against the owner of the lot.