No person shall develop land without obtaining a final project approval in accordance with § 164-1.3A(3) to control or manage runoff from such development except as provided within § 164-3.0. Stormwater management measures shall be designed consistent with the Design Manual and constructed according to an approved plan.
The following development activities are exempt from the provisions of this chapter:
A. 
Agricultural land management practices;
B. 
Additions or modifications to existing single-family detached residential structures if they comply with § 164-3.2C of this chapter;
C. 
Any developments that do not disturb over 5,000 square feet of land area; and
D. 
Land development activities that the Administration determines will be regulated under specific state laws, which provide for managing stormwater runoff.
A. 
Except as provided in § 164-3.3B and D of this chapter, the County Engineer shall grant stormwater management quantitative control waivers only to those projects within areas where watershed management plans have been developed consistent with § 164-3.3G of this chapter. Requests for quantitative stormwater management waivers shall be in writing and shall contain sufficient descriptions, drawings, and other information necessary to demonstrate that ESD has been implemented to the MEP. A separate written waiver request shall be required in accordance with the provisions of this section if there are subsequent additions, extensions, or modifications to a development that has received a waiver.
B. 
Except as provided in § 164-3.3D of this chapter, if watershed management plans consistent with § 164-3.3G of this chapter have not been developed, a stormwater management quantitative control waiver may be granted to the following types of projects, provided that ESD has been implemented to the MEP:
(1) 
That have direct discharge to tidally influenced receiving waters; or
(2) 
That are in-fill development located in a priority funding area where the economic feasibility of the project is tied to the planned density, and where implementation of the 2009 regulatory requirements would result in a loss of the planned development density, provided that:
(a) 
Public water and sewer and stormwater conveyance exist;
(b) 
The quantitative waiver is applied only to the impervious cover that previously existed on the site;
(c) 
ESD to the MEP is used to meet the full water quality treatment requirements for the entire development; and
(d) 
ESD to the MEP is used to provide full quantity control for all new impervious surfaces; or
(3) 
When the approving agency determines that existing circumstances reasonably prevent implementation of quantity control practices.
C. 
Except as provided in § 164-3.3D of this chapter, stormwater management qualitative control waivers apply only to:
(1) 
In-fill development projects where ESD has been implemented to the MEP and other BMPs are not feasible;
(2) 
Redevelopment projects where the requirements of § 164-3.4 of this chapter are satisfied; or
(3) 
Sites where the approving agency determines that existing circumstances reasonably prevent implementation of ESD to the MEP.
D. 
Stormwater management quantitative and qualitative control waivers may be granted for phased development projects if a system designed to meet the 2000 regulatory requirements and the County ordinance for multiple phases has been constructed by May 4, 2010. If the 2009 regulatory requirements cannot be met for future phases constructed after May 4, 2010, all reasonable efforts to incorporate ESD in future phases must be demonstrated.
E. 
Waivers shall be granted only when it has been demonstrated that ESD has been implemented to the MEP. Waivers shall:
(1) 
Be based on the unique circumstances of a specific development on a case-by-case basis;
(2) 
Consider the cumulative effects of any previous County waiver; and
(3) 
Reasonably ensure the development will not adversely impact stream quality.
F. 
If the County has established an overall watershed management plan for a specific watershed, then the County may develop quantitative waiver and redevelopment provisions that differ from § 164-3.3D and § 164-3.4 of this chapter.
G. 
A watershed management plan developed for the purpose of implementing different stormwater management policies for waivers and redevelopment shall:
(1) 
Include detailed hydrologic and hydraulic analyses to determine hydrograph timing;
(2) 
Evaluate both quantity and quality management and opportunities for ESD implementation;
(3) 
Include a cumulative impact assessment of current and proposed watershed development;
(4) 
Identify existing flooding and receiving stream channel conditions;
(5) 
Be performed on a reasonable scale;
(6) 
Specify where on-site or off-site quantitative and qualitative stormwater management practices are to be implemented;
(7) 
Be consistent with the General Performance Standards for Stormwater Management in Maryland of the Design Manual; and
(8) 
Be approved by the Administration.
A. 
Stormwater management plans are required by the County for all redevelopment, unless otherwise specified by watershed management plans adopted pursuant to § 164-3.3G of this chapter. Stormwater management measures must be consistent with the Design Manual.
B. 
All redevelopment designs shall either:
(1) 
Reduce impervious area within the limit of disturbance (LOD) by at least 50% according to the Design Manual; or
(2) 
Implement ESD to the MEP to provide water quality treatment for at least 50% of the existing impervious area within the LOD; or
(3) 
Use a combination of § 164-3.4B(1) and § 164-3.4B(2) above for at least 50% of the existing site impervious area.
C. 
Alternative stormwater management measures may be used to meet the requirements in § 164-3.4B of this chapter if the applicant demonstrates to the satisfaction of the County Engineer that impervious area reduction has been maximized and ESD has been implemented to the MEP. Alternative stormwater management measures include, without limitation:
(1) 
On-site structural BMPs;
(2) 
Off-site structural BMPs that provide water quality treatment for an area equal to or greater than 50% of the existing impervious area; or
(3) 
A combination of impervious area reduction, ESD implementation, and on-site or off-site structural BMPs for an area equal to or greater than 50% of the existing site impervious area within the LOD.
D. 
The County may develop separate policies for providing water quality treatment for redevelopment projects if the requirements of § 164-3.4B and C of this chapter cannot be met. Any separate redevelopment policy shall be reviewed and approved by the Administration and may include, without limitation:
(1) 
A combination of ESD and on- or off-site structural BMPs;
(2) 
Retrofitting, including upgrades to existing BMPs, filtering practices, and off-site ESD implementation;
(3) 
Participation in a stream restoration project;
(4) 
Pollution trading;
(5) 
Payment of a fee-in-lieu; or
(6) 
A partial waiver of the treatment requirements if ESD is not practicable.
E. 
If the County Engineer determines that it is not practical to meet the 2009 regulatory requirements using ESD on a specific redevelopment project, the County Engineer shall consider alternatives in § 164-3.4D(1) through (6) above, in order of priority in deciding what alternatives shall be required. The County Engineer's decision may consider without limitation:
(1) 
Whether the project is in an area targeted for development incentives, such as a priority funding area, a designated transit-oriented development area, or a designated base realignment and closure revitalization and incentive zone;
(2) 
Whether the project is necessary to accommodate growth consistent with the County Comprehensive Plan; or
(3) 
Whether bonding and financing have already been secured based on an approved development plan.
F. 
For any net increase in impervious area on a redevelopment project, stormwater management shall be treated as new development in accordance with § 164-4.0.
The County Engineer may grant, in writing, a variance from any requirement of § 164-4.0, Stormwater Management Criteria, if there are unique physical characteristics of the site such that strict adherence to the requirements of this chapter will cause unnecessary hardship. The applicant shall submit a written request for a variance to the County Engineer, which shall fully describe the specific variance sought, and reasons for the request. The County Engineer shall not grant a variance without satisfactory evidence that implementation of ESD to the MEP has been investigated thoroughly and the above requirements for a variance have been met.