7 Del. Admin. Code § 5101
1.1 Findings of Fact
1.1.1 It is determined that:
1.3 Applicability
1.3.1 Unless a particular activity is exempted by these regulations, a person shall not disturb land without an approved Sediment and Stormwater Management Plan from the Department or Delegated Agency. A Sediment and Stormwater Management Plan shall not be approved for a property unless it is consistent with the following items:
1.3.2 Applicability of these regulations for plans that have been approved to comply with previous regulations shall be consistent with the following:
1.3.2.2 Plans approved to comply with regulations in effect prior to January 1, 2014 where construction has commenced may be extended based on the requirements in place at the time of original Plan approval. In no case shall the plan extension supersede the sunset provisions of the county or local government.
1.3.2.4 An individual building pad site, outparcel or future phase which was considered in an overall master plan stormwater management design and where the stormwater management facility has been constructed based upon regulations in effect prior to January 1, 2014 shall be grandfathered under the regulations in place at the time of approval of the master plan project.
1.4 The following activities are exempt from both sediment control and stormwater management requirements established by these regulations:
1.5 Variances
1.5.3 The Department shall consider and decide applications for a variance from the provisions of these Regulations if all of the following are established by the applicant.
1.6 Fees and Financial Guarantees
1.6.1 Fees
1.6.1.2 The establishment of fees, not involving stormwater utilities, shall be in accordance with the following items:
1.6.2 Financial Guarantee
16.2.1.1 The Owner shall submit when required to the Department or Delegated Agency a financial guarantee before the onset of construction activities. The financial guarantee will ensure that action can be taken by the Department or Delegated Agency to complete required elements of the approved Sediment and Stormwater Management Plan, at the Owner's expense, should the Owner fail to initiate, complete, or maintain those measures identified in the approved Sediment and Stormwater Management Plan after being given proper notice and within a reasonable time specified by the Department or Delegated Agency.
The following words and terms, when used in this regulation, shall have the following meaning unless the context clearly indicates otherwise:
“Adequate conveyance”means any system having sufficient capacity to transport the runoff generated during the Resource Protection Event, Conveyance Event, and Flooding Event; functions and discharges in a non-erosive manner; and does not adversely impact any offsite properties, conveyance system, stormwater facility, or State Waters.
“Adverse impact”means a negative impact resulting from a construction or development activity. The negative impact may include, but is not limited to, increased risk of flooding; degradation of water quality; increased sedimentation; reduced groundwater recharge; negative impacts on aquatic habitat; or threatened public health and safety.
“Agricultural land management practices”means those methods and procedures generally accepted by the Conservation Districts and used in the cultivation of land in order to further crop and livestock production and conservation of related soil and water resources.
“Agricultural structure” means a structure on a farm used solely for agricultural purposes in which the use is exclusively in connection with the production, harvesting, storage, drying, or raising of agricultural commodities, including the raising of livestock. Structures used for human habitation, public use, or a place of employment where agricultural products are processed, treated, or packaged are not considered agriculture structures for the purposes of these regulations.
“Applicant” means a person who has requested approval of a Sediment and Stormwater Management Plan through submittal of an application in accordance with these regulations or who has requested permission to conduct any activity subject to these regulations.
“Best available technology” or “BAT” means a level of technology based on the very best (state of the art) sediment and stormwater control and treatment measures that have been developed or are capable of being developed and that are economically achievable.
“Best management practices” or “BMPs”means schedules of activities, prohibition of practices, maintenance procedures, and other management practices or measures to prevent or reduce the discharge of pollutants. BMPs include the following, among other practices and measures: structural and non-structural controls; treatment requirements; operating procedures and practices to control site runoff.
“Biosolids” means solid or semi-solid material obtained from treated wastewater or animal manure.
“Brownfield”means any vacant, abandoned or underutilized real property the development or redevelopment of which may be hindered by the reasonably held belief that the real property may be environmentally contaminated.
“Certified Construction Reviewer” or “CCR”means those individuals, having passed a Departmental sponsored or approved training course and holding current certification, which provide on-site construction review for sediment control and stormwater management in accordance with these regulations.
“Conservation plan”means a customized document that outlines the use and best management practices of the natural resources on a parcel of land.
“Conveyance event”means the runoff event produced by a storm having an annual probability of occurrence of 10%.
“Conveyance event volume” or “Cv” means the volume of runoff generated by the Conveyance Event that is not otherwise reduced for the Resource Protection Event.
“Dedication”means transferring ownership of a stormwater management system to a delegated agency, public utility, municipality, stormwater utility, or private entity, along with all associated easements, escrow funds, and maintenance responsibilities.
“Delegated Agency”means the Conservation District, county, municipality, or State agency that has accepted responsibility in a jurisdiction for implementation of one or more elements of the Sediment and Stormwater Program within that jurisdiction.
“Delegation”means the acceptance of responsibility by a Conservation District, county, municipality, or State agency for the implementation of the Sediment and Stormwater Program.
“Department” means the Department of Natural Resources and Environmental Control.
“Designated watershed or subwatershed” means a watershed or subwatershed proposed by a conservation district, county, municipality, or State agency and approved by the Department. The Department may establish additional requirements due to existing water quantity or water quality problems. These requirements shall be implemented on an overall watershed or subwatershed master plan developed for water quality or water quantity protection.
“Detailed plan”means a plan developed by a Licensed Professional in the State of Delaware which does not meet standard plan criteria.
“Drainage area”means that area contributing runoff to a single point measured in a horizontal plane, which is enclosed by a ridge line.
“Easement”means a grant or reservation by the Owner of land for the use of land by others for a specific purpose or purposes, and which must be included in the conveyance of land affected by the easement.
“Effective imperviousness”, for the purposes of these Regulations, means the equivalent percentage of a site’s impervious area that directly contributes stormwater runoff during the Resource Protection Event after all runoff reduction practices have been implemented.
“Erosion and sediment control”means the control of solid material, both mineral and organic, during a land disturbing activity, to prevent its transport out of the disturbed area by means of wind, water, gravity, or ice.
“Final stabilization” means that:
(1) All soil disturbing activities at the site have been completed and either of the two following criteria are met:
(3) For individual lots in residential construction, final stabilization means that either:
(4) For construction projects on land used for agriculture purposes (e.g., pipelines across crop or range land, staging areas for highway construction, etc.) final stabilization may be accomplished by returning the disturbed land to its preconstruction agriculture use. Areas disturbed that were not previously used for agricultural activities, such as buffer strips immediately adjacent to a “water of the United States” and areas which are not being returned to their preconstruction agricultural use must meet the final stabilization criteria (1) or (2) above.
“Financial guarantee” means a bond, security, letter of credit, etc. provided by the Owner to serve as a payment source should the Owner fail to meet the obligations and requirements of the approved Sediment and Stormwater Management Plan.
“Flooding event”means the runoff event produced by a storm having an annual probability of occurrence of 1.0%.
“Flooding event volume” or “Fv” means the volume of runoff generated by the Flooding Event that is not otherwise reduced for the Resource Protection Event and the Conveyance Event.
"Forest" means a biological community dominated by trees and other woody plants covering a land area of one contiguous acre or greater, and that have at least 100 trees per acre with at least 50% of those trees having a two inch or greater diameter at 4.5 feet above the ground and larger. Forest does not include orchards or other stands of trees having a curve number equivalent to "woods-grass combination". To determine whether a site meets the definition of a forest at the baseline condition of2017, the Department or its authorized Delegated Agency may use data from various sources, including but not limited toLand Use/Land Cover data, historic and recent aerial photography, field collected data, etc.
“Functional equivalency” means alternative measures that are consistent with the policies, procedures, technical specifications, and advisory provisions found in the regulatory guidance documents, and which satisfy these Regulations.
“Impervious surface” means a surface which either prevents or retards the entry of water into the soil.
“Infiltration”means the passage or movement of water into the soil profile.
"Inspection port" means an appurtenance installed within a stormwater management system to allow for observation of conditions, including water level, located below the surface.
“Land disturbing activity” means a land change or construction activity for residential, commercial, industrial, and institutional land development which may result in soil erosion from water or wind, or the movement of sediments or pollutants into state waters or onto lands in the State; or which may result in accelerated stormwater runoff, including, but not limited to, clearing, grading, excavating, transporting and filling of land.
“Licensed Professional in the State of Delaware”means a design professional licensed under 24 Del.C. Ch. 2, 24 Del.C. Ch. 27, or 24 Del.C. Ch. 28.
“Maintenance” means the work of keeping stormwater management systems including access routes and appurtenances (grade surfaces, walls, drains, dams and structures, vegetation and other protective devices) in a safe and functioning condition as the system was designed. Routine or minor maintenance includes grass mowing and trimming, debris removal, minor sediment removal, filling eroded areas and animal burrows, and removal of trees and shrubs on embankments. Non-routine or major maintenance includes structural repair, major sediment removal and major erosion repair, and invasive aquatic vegetation removal.
“Maximum extent practicable” or “MEP” means, for the purpose of these Regulations, using stormwater management measures, techniques and methods that are available and capable of being implemented while taking into consideration cost, available technology, and project site constraints.
“Notice of Completion”means a document issued by the Department or Delegated Agency at the end of project construction when all items and conditions of the approved Sediment and Stormwater Management Plan have been satisfied, post construction verification documents demonstrate that the stormwater management systems have been constructed in accordance with the approved Sediment and Stormwater Management Plan, and final stabilization of disturbed areas on the site has been achieved.
“Offset” means an alternate to strict adherence to the regulations including, but not limited to trading, banking, fee-in-lieu, or other similar program that serves as compensation when the requirements of these regulations cannot be reasonably met on an individual project basis.
“Operation and Maintenance Plan” means the plan which identifies required maintenance for stormwater management systems.
“Owner” means a person who has a legal interest in lands of this State, or who has an equitable interest in lands of this State, except when a person holds an interest in those lands as a security interest, unless through foreclosure or other action the holder has taken possession of those lands, and who undertakes, or for whose benefit, activities subject to these regulations are commenced or carried out on those lands, or the person responsible for maintenance of stormwater management systems constructed to comply with these regulations on those lands.
“Person”means a State or federal agency, individual, partnership, firm, association, joint venture, public or private corporation, trust, estate, commission, board, public or private institution, utility, cooperative, municipality or other political subdivision of this State, an interstate body or any other legal entity.
“Permanent stabilization” means the establishment of perennial vegetation by application of soil amendments, seed, and mulch in accordance with methods accepted by the Department on disturbed areas that have reached final grade in order to stabilize the soil, prevent erosion, and reduce sediment and runoff to downstream or offsite areas.
“Post construction verification documents” means a set of surveyed plans reflecting the as-built condition of stormwater management measures and may also include supporting computations and specifications as required by the Department or the Delegated Agency.
"Pretreatment" means a mechanism at or before an inlet to a stormwater management practice that reduces gross pollutants and sediment from compromising the performance and to maximize the maintenance interval of the practice.
“Redevelopment”, including brownfield development, means a construction, alteration or improvement, including but not limited to the demolition or building of structures, filling, grading, paving, or excavating, where existing land use is residential, commercial, industrial, or institutional. Ordinary maintenance activities, remodeling of existing buildings, resurfacing of paved areas, and exterior changes or improvements are typically not considered redevelopment activities for the purposes of these regulations.
“Resource protection event” means the runoff event produced by a storm having an annual probability of occurrence of 99%.
“Resource protection event volume” or “RPv” means the annualized volume of runoff generated by the Resource Protection Event.
“Responsible personnel” means a foreman or superintendent who is in charge of on-site clearing and land disturbing activities for sediment and stormwater control associated with a construction project.
“Runoff reduction practices” means stormwater best management practices that reduce total runoff volume from a developed site through canopy interception, surface recharge, evaporation, rainfall harvesting, engineered infiltration, or evapotranspiration and may include practices that delay the delivery of stormwater to a surface discharge.
“Sediment” means soils or other surficial materials transported or deposited by the action of wind, water, ice or gravity as a product of erosion.
“Sediment and Stormwater Management Plan” means a plan for the control of soil erosion, sedimentation, stormwater quantity, and water quality impacts resulting from a land disturbing activity, through both the construction and post construction phases of development.
“Standard plan” means a set of pre-defined standards or specifications for minor land disturbing activities that may preclude the need for the preparation of a detailed plan under specific conditions.
“State waters” means any and all waters, public or private, on the surface of the earth which are contained within, flow through or border upon the State or any portion thereof.
"Stone" means a hard non-metallic mineral building material, and for the purposes of this regulation shall be interchangeable with "gravel" and "aggregate".
“Stormwater” means the runoff of water from the surface of the land resulting from precipitation, or snow or ice melt.
“Stormwater management” means:
(b) For water quality control, a system of vegetative, structural, and other measures that controls adverse effects on water quality that may be caused by land disturbing activities upon the land.
"Stormwater management offset" means an alternative method of compliance to the regulations including, but not limited to, trading, banking, fee-in-lieu, or other similar program.
"Stormwater management offset district" means an organization established to administer stormwater management offsets established under Department authorization.
“Stormwater management system” means vegetative, structural, and other facilities or measures, singularly or in combination, as defined in Section 11.0, that provide stormwater management.
“Stormwater utility” means an administrative organization that has been established for the purposes of funding sediment control, stormwater management or flood control planning, design, construction, maintenance, and overall resource needs by authorized and imposed charges.
“Temporary stabilization” means planting quick-growing vegetation and applying anchored straw mulch or other means to stabilize the soil and prevent erosion of a disturbed area until permanent vegetation or other stabilization measures can be established.
"Third party CCR" means, for the purposes of these regulations, any individual CCR that is not an employee of the owner or a contractor of the construction activity, excluding the site designer.
“Tidal waters”means any water that alternately rises and falls in a predictable and measurable rhythm or cycle due to the gravitational attraction of the moon and sun and is under the regulatory authority of 7 Del.C. Ch. 72.
“Transfer” means to convey responsibility for maintenance of a stormwater management system to a new Owner.
“Variance”means a permitted deviation from an established rule or regulation, or plan, or standard or procedure.
“Water quality” means those characteristics of stormwater runoff from a land disturbing activity that relate to the chemical, physical, biological, or radiological integrity of water.
“Water quantity” means those characteristics of stormwater runoff that relate to the rate, volume and duration of flow to downstream areas resulting from land disturbing activities.
“Watershed”means the drainage area contributing stormwater runoff to a single point.
“Watershed plan” means a comprehensive study of the activities and sources that contribute to water quality or water quantity problems and identifies the location of those problem areas within a specific watershed boundary. It also serves as a framework for how, where and what stormwater management tools will be applied to address those water quality or water quantity problems.
3.1 All projects requiring approval of a detailed Sediment and Stormwater Management Plan are subject to a three-step approval process. Step 1 of the plan approval process is scheduling and conducting the Project Application Meeting. Step 2 of the plan approval process is submission of the Preliminary Sediment and Stormwater Management Plan. Step 3 of the plan approval process is submission of the Sediment and Stormwater Management Plan.
3.2 Project Application Meeting
3.3 Preliminary Sediment and Stormwater Management Plan
3.4 Sediment and Stormwater Management Plan
3.4.1 The Sediment and Stormwater Management Plan submittal shall consist of the following elements: Construction Site Stormwater Management Plan including pollution prevention elements, Post Construction Stormwater Management Plan, final hydrologic and hydraulic computations, Operation and Maintenance Plan, and a copy of the preliminary Record Plan as required by the local land use approval agency. The plan shall also include the following notes:
3.5 Review Procedures for Plan Submittals
3.6 Expiration of Plan Approval
3.6.1 Approved plans remain valid for five years from the date of an approval, unless specifically extended by the Department or Delegated Agency. The basis for extension may include, but is not limited to, the following items:
3.7 Standard Plans
3.7.1 In the event that a project meets the Standard Plan Applicability Criteria for the project type, that project has the option to comply with Standard Plan Conditions for the project type in lieu of developing a detailed Sediment and Stormwater Management Plan for the project. Project types for which Standard Plan Applicability Criteria has been developed include:
3.7.11 Residential construction less than 1.0 acre disturbed
3.7.11.2 Applicability criteria:
3.7.12 Residential construction greater than or equal to 1.0 acre disturbed
3.7.12.2 Applicability criteria:
3.7.12.2.3 One of the following will be met on any individual lot:
3.7.12.3 Conditions:
3.7.12.3.1 Standard nutrient management plan recommendations will be followed for the project, during construction and throughout the life of the project.
3.7.12.3.2 Discharges from rooftops will be disconnected to the maximum extent practicable using a method approved by the Department or Delegated Agency. For example:
3.7.13 Non-residential construction less than 1.0 acre disturbed
3.7.13.1 Applicability criteria:
3.7.13.1.4 For project site locations within an area previously unmanaged for stormwater quantity and quality under an approved Sediment and Stormwater Plan, one of the following is met:
3.7.13.2 Conditions:
3.7.13.2.1 Discharges from rooftops will be disconnected to the maximum extent practicable using one of the following methods or another method approved by the Department or Delegated Agency:
3.7.14 Tax Ditch Maintenance
3.7.14.2 Conditions:
3.7.15 Minor Linear Utility Disturbance
3.7.15.1 Applicability criteria.
3.7.15.1.2 One of the following is met:
3.7.15.1.2.2 Total disturbance is 5.0 acres or less, and
3.7.15.2 Conditions:
3.7.16 Stormwater Facility Maintenance
3.7.16.2 Conditions:
3.7.17 Agricultural Structure Construction
3.7.17.1 Applicability criteria.
3.7.17.2 Conditions:
3.7.18 Poultry House Construction
3.7.18.1 Applicability criteria.
3.7.18.2 Conditions.
3.7.19 Demolition
3.7.19.1 Applicability criteria.
3.7.20 BMP Construction and Retrofit
3.7.20.1 Applicability criteria:
3.7.20.1.1 The construction will provide either:
3.7.20.2 Conditions:
3.7.20.2.2 Discharges from added impervious areas will be disconnected to the maximum extent practicable using one of the following methods or another method approved by the Department or Delegated Agency:
3.7.21 Minor Bridge and Culvert Construction
3.7.21.1 Applicability criteria:
3.7.21.2 Conditions:
3.7.21.2.1 Impervious surfaces will be graded to sheet flow to pervious areas to the maximum extent
practicable.
3.7.22 Sidewalk, Trail, or Other Linear Impervious Surfaces
3.7.22.1 Applicability criteria:
3.7.22.1.5 For project site locations within an area previously unmanaged for stormwater quantity and quality under an approved Sediment and Stormwater Plan, one of the following is met:
3.7.22.2 Conditions:
3.8 Plan Certifications
4.4 Limits on Land Disturbance
4.4.2 If approved by the Department or Delegated Agency sites may disturb greater than 20 acres. Sites having disturbed areas greater than 20 acres shall comply with the following:
4.4.2.1 Construction site stormwater management BMPs shall be designed for disturbed drainage areas greater than 20 acres and shall have supporting design computations, including but not limited to storage, conveyance, stability, and treatment capabilities based on the 2-year storm event with bare earth conditions.
4.5 Stabilization
5.1 Post construction stormwater management plans shall be designed in accordance with the following:
5.1.7 Post construction stormwater management BMPs shall meet the following requirements:
5.2 Resource Protection Event Criteria
5.2.3 Compliance with subsection 5.2 shall be accomplished to the maximum extent practicable through the following provisions:
5.2.3.1 Treatment of runoff from the RPv event with Best Management Practices (BMPs) as set forth in Section 11.0 shall meet the following requirements:
5.3 Conveyance Event Criteria
5.3.3 Compliance with subsection 5.3 shall be accomplished through the following provisions:
5.4 Flooding Event Criteria
5.4.3 Compliance with subsection 5.4 shall be accomplished through the following provisions:
5.5 Alternative Criteria
5.6 Redevelopment Criteria
5.6.2 Compliance with the Resource Protection Event as defined in subsection 5.2.2 shall be accomplished to the maximum extent practicable for redevelopment projects through the following provisions:
5.6.2.3 Redevelopment on sites with stormwater management systems designed and functioning in accordance with the Delaware Sediment and Stormwater Regulations first promulgated on January 23, 1991:
5.6.2.4 Redevelopment on sites without stormwater management systems designed and functioning in accordance with the Delaware Sediment and Stormwater Regulations first promulgated on January 23, 1991:
6.1 Owner Responsibilities
6.2 Contractor Training Requirements
6.3 Certified Construction Reviewer Requirements
6.3.1 The Certified Construction Reviewer shall be responsible for reviewing construction activities and reporting on the adequacy of construction in accordance with the approved Sediment and Stormwater Management Plan, in addition to the following items:
6.3.2 The Certified Construction Reviewer shall function under the direction of a registered professional engineer (P.E.) licensed to practice engineering in the State of Delaware. The following applies to the P.E.'s responsibilities:
6.4 Department or Delegated Agency Construction Reviews
6.5 Required Construction Reviews and Notification Steps
6.5.6 Upon project completion a final construction review shall be conducted and a final review report shall be completed by the Department or Delegated Agency to ensure compliance with the approved Sediment and Stormwater Management Plan. The Department or Delegated Agency shall issue a Notice of Completion for a project when all of the following criteria have been met:
7.1 Stormwater management systems constructed to comply with7Del.C.Ch. 40 and these regulations shall be maintained in accordance with the provisions of this section.
7.2 Owner Responsibilities
7.2.1 The Owner shall ensure that the stormwater management system is functioning in accordance with the approved engineering design, within the tolerances of the accepted post construction verification documents, and in compliance with these regulations. The Owner will promptly repair and restore stormwater management systems.
7.3 Maintenance Reviews
7.4 Minimum Maintenance Requirements
8.2 The Delegated Agency may, in addition to local enforcement options, refer a site violation to the Department for additional enforcement action. Referral of a site violation to the Department may initiate a Departmental construction review of the site to verify site conditions. That construction review may result in the following actions:
8.3 Failure of the person engaged in the land disturbing activity or the contractor to comply with Departmental requirements may result in the following actions in addition to other penalties as provided in Chapter 40 of Title 7 of the Delaware Code.
9.1 The provisions of these regulations may be delegated to the Conservation Districts, counties, municipalities, or State agencies. Initial consideration regarding delegation of program elements shall be given to the Conservation Districts.
11.1 Infiltration Practices
11.1.1 Infiltration practices are defined as practices that capture and temporarily store the design storm volume before allowing it to infiltrate into the soil over a two day period. Design variants include:
11.1.2 Infiltration practices receive 100% retention volume credit (Rv) for the volume stored and infiltrated by the practice.
11.1.3 Infiltration Feasibility Criteria
11.1.4 Infiltration Conveyance Criteria
11.1.5 Infiltration Pretreatment Criteria
11.1.6 Infiltration Design Criteria
11.1.6.7 Infiltration practices shall be designed so that they will:
11.1.6.8 All Infiltration practices must be designed so as to be accessible for maintenance.
11.1.6.8.3 Maintenance access must meet the following criteria:
11.1.7 Infiltration Construction Criteria
11.1.7.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.1.7.4 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the infiltration practice has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for infiltration practices are as follows:
11.2 Bioretention
11.2.1 Bioretention is defined as practices that capture and store stormwater runoff and pass it through a bed of engineered soil media comprised of sand, lignin and organic matter, known as biosoil. Filtered runoff may be collected and returned to the conveyance system, or allowed to infiltrate into the soil. Design variants include:
11.2.2 Bioretention Stormwater Credit Calculations
11.2.2.3 Bioretention with underdrain
11.2.2.4 Bioretention with infiltration
11.2.3 Bioretention Feasibility Criteria
11.2.4 Bioretention Conveyance Criteria
11.2.5 Bioretention Pretreatment Criteria
11.2.6 Bioretention Design Criteria
11.2.6.3 Bioretention practices shall be designed so that they will:
11.2.6.5 Biosoil Media
11.2.6.5.1 The Biosoil-14 soil mixture shall have the following volumetric composition:
11.2.6.6 A surface cover shall be provided over the biosoil media.
11.2.6.7 Underdrains
11.2.6.10 All Bioretention practices must be designed so as to be accessible for maintenance.
11.2.6.10.3 Maintenance access must meet the following criteria:
11.2.7 Bioretention Landscaping Criteria
11.2.7.1 A planting plan shall be provided for all bioretention facilities. Minimum elements of a planting plan include the following:
11.2.8 Bioretention Construction Criteria
11.2.8.1 When a bioretention system is used as a sediment trap or basin during construction, the Sediment & Stormwater Plan must include notes and graphic details specifying that:
11.2.8.5 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.2.8.6 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the bioretention practice has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for bioretention practices are as follows:
11.3 Permeable Pavement Systems
11.3.1 Permeable Pavement Systems are defined as paving surfaces that capture and temporarily store stormwater by filtering runoff through voids in the pavement surface into an underlying reservoir. Design variants include:
11.3.2 Permeable Pavement Systems receive 100% retention volume credit (Rv) for the volume stored and infiltrated by the practice.
11.3.3 Permeable Pavement Feasibility Criteria
11.3.3.1 Drainage Area. For parking lots and roadways configurations:
11.3.3.2 Soils and Overdrains. Parking lot and roadway configurations utilizing permeable pavement shall meet the following requirements:
11.3.5 Permeable Pavement Design Criteria
11.3.5.2 Internal Geometry and Drawdown
11.3.5.2.3 Permeable pavement practices shall be designed so that they will:
11.3.5.3 Reservoir layer
11.3.6 Permeable Pavement Construction
11.3.6.9 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.3.6.10 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the permeable pavement has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for permeable pavement are as follows:
11.4 Vegetated Roofs
11.4.1 Vegetated Roofs are defined as practices on top of buildings that capture and store rainfall in an engineered growing media, which is designed to support plant growth. A portion of the captured rainfall evaporates or is taken up by plants, which helps reduce runoff volumes, peak runoff rates, and pollutant loads on development sites. Design variants include:
11.4.2 Vegetated Roofs receive annual runoff reduction credit (RR) for the contributing roof area, along with associated pollutant removals as follows:
11.4.3 Vegetated Roof Feasibility Criteria
11.4.4 Vegetated Roof Conveyance Criteria
11.4.5 Vegetated Roof Design Criteria
11.4.5.3 Waterproof membranes designed for burial in Vegetated Roofs do not require supplemental root barriers; however root barriers are required in combination with some waterproof membranes.
11.4.5.6 Growth Media
11.4.5.6.6 For a Vegetated Roof to be regarded as neutral with respect to phosphorous (P) loading in runoff, the P content of the growth media must be controlled.
11.4.5.7 Plant cover
11.4.5.7.1 Initial planting plan shall be designed such that mature plant coverage within 24 months of initial planting shall be:
11.4.5.8 Vegetated Roof sizing
11.4.6 Vegetated Roof Landscaping Criteria
11.4.7 Vegetated Roof Construction
11.4.7.1 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.4.7.2 Post Construction Verification Documentation
11.4.7.2.1 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the Vegetated Roof has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for Vegetated Roofs are as follows:
11.4.8 Vegetated Roof Maintenance Criteria
11.4.8.1 Maintenance Reviews
11.5 Rainwater Harvesting
11.5.1 Rainwater harvesting is defined as systems that intercept, divert, store and release rainfall for future use. Rainwater that falls onto impervious surfaces is collected and conveyed into an above- or below-ground cistern, where it can be used for non-potable water uses and on-site stormwater disposal or infiltration. Runoff collected and temporarily stored in more traditional stormwater management practices constructed in accordance with the Post Construction Stormwater BMP Standards and Specifications, such as wet ponds, can also be used for irrigation purposes to achieve these same goals. Design variants include:
11.5.2 Rainwater Harvesting Stormwater Credit Calculations
11.5.2.2 Seasonal Rainwater Harvesting Performance Credits
11.5.2.3 Continuous Rainwater Harvesting Performance Credits
11.5.3 Rainwater Harvesting Feasibility Criteria
11.5.4 Rainwater Harvesting Conveyance Criteria
11.5.4.2 Overflow
11.5.5 Rainwater Harvesting Pretreatment Criteria
11.5.6 Rainwater Harvesting Design Criteria
11.5.6.1 The following factors that must be considered when designing a Rainwater Harvesting system and selecting a cistern:
11.5.6.2 Distribution Systems
11.5.6.3 Rainwater Harvesting Material Specifications
11.5.6.4 Sizing of Rainwater Harvesting Systems
11.5.6.5 All Rainwater Harvesting Systems must be designed so as to be accessible for maintenance.
11.5.6.5.3 Maintenance access must meet the following criteria:
11.5.8 Rainwater Harvesting Construction
11.5.8.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.5.8.3 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the rainwater harvesting practice has been constructed in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Items to be checked and verified are as follows:
11.6 Restoration Practices
11.6.2 Design variants for Restoration Practices include:
11.7 Rooftop Disconnection
11.7.2 Rooftop Disconnection that meets the minimum full disconnection length shall receive the following annual runoff reduction and pollutant reduction credits:
11.7.4 Rooftop Disconnection Feasibility Criteria
11.7.7 Rooftop Disconnection Design Criteria
11.7.7.3 The minimum full disconnection lengths shall be as follows:
11.7.10 The Sediment and Stormwater Plan shall include the following operation and maintenance notes for Rooftop Disconnection:
11.8 Vegetated Channels
11.8.1 Vegetated channels are open conveyances planted with grass or other suitable vegetation and having a shallow depth of flow to allow runoff to be filtered and recharged along the length of the channel. Design variants include:
11.8.2 Vegetated channels receive the following annual runoff reduction and pollutant reduction credits.
11.8.3 Vegetated Channel Feasibility Criteria
11.8.4 Vegetated Channel Conveyance Criteria
11.8.6 Vegetated Channel Design Criteria
11.8.6.1 Channel Geometry
11.8.6.2 Check Dams
11.8.6.5 Adequate conveyance and treatment capacity shall be provided in accordance with the following guidelines:
11.8.6.5.8 Hydraulic residence time is the time for runoff to travel the full length of the channel. For both Bioswales and Grassed Channels hydraulic residence time is computed based upon 50% of the RPv peak flow rate.
11.8.6.6 All Vegetated Channels must be designed so as to be accessible for maintenance.
11.8.6.6.3 Maintenance access must meet the following criteria:
11.8.7 Vegetated Channel Landscaping Criteria
11.8.8 Vegetated Channel Construction
11.8.8.1 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.8.8.2 Post Construction Verification Documentation.
11.8.8.2.1 Upon facility completion, the owner shall submit post construction verification documents as follows to demonstrate that the vegetated channel has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency:
11.9 Sheet Flow to Vegetated Filter Strip or Vegetated Open Space
11.9.1 Vegetated areas can treat sheet flow delivered from adjacent impervious and managed turf areas by slowing runoff velocities and allowing sediment and attached pollutants to settle or be filtered by the vegetation. Vegetation can consist of grasses, planted trees, or existing forest. Design variants include:
11.9.2 Sheet Flow practices receive the following annual runoff reduction and pollutant reduction credits.
11.9.2.1 The RPv runoff reduction performance credit for a Vegetated Filter Strip on A/B soil or compost amended C soil is as follows:
11.9.2.2 The RPv runoff reduction performance credit for a Vegetated Filter Strip on C/D soil is as follows:
11.9.2.3 The RPv runoff reduction performance credit for Sheet Flow to Vegetated Open Space on A/B soil or compost amended C soil is as follows:
11.9.2.4 The RPv runoff reduction performance credit for Sheet Flow to Vegetated Open Space on C/D soil is as follows:
11.9.3 Sheet Flow Feasibility Criteria
11.9.4 Sheet Flow Design Criteria
11.9.4.1 Stormwater shall enter the filter strip or open space as sheet flow.
11.9.4.2 Vegetated Filter Strip
11.9.4.2.2 Vegetated Filter Strips shall have the following minimum lengths, measured in the direction of flow, unless calculations are provided in accordance with the Computational Method of Compliance.
11.9.4.3 Vegetated Open Space
11.9.4.4 Computational Method of Compliance.
11.9.4.4.1 Vegetated Filter Strips using the Computational Method of Compliance shall meet the following criteria in order to receive RPv runoff reduction credits listed above:
11.9.4.4.2 Adjusted RPv runoff reduction credit based on the ratio of the computed residence to the minimum residence time shall be applied to Vegetated Filter Strips that meet the maximum depth of flow criteria.
11.9.5 Sheet Flow Landscaping Criteria
11.9.6 Sheet Flow Construction
11.9.6.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.9.6.3 Post Construction Verification Documentation.
11.9.6.3.1 Upon facility completion, the owner shall submit Post Construction Verification Documents at the discretion of the Department or Delegated Agency as follows to demonstrate that the Vegetated Filter Strip or Vegetated Open Space has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. The following items, as applicable, shall be included in the Post Construction Verification Documentation for Sheet Flow Practices:
11.9.6.3.2 Constructed allowable tolerances for vegetated filter strips and vegetated open spaces, if disturbed, shall be within the tolerances of design geometrics for the following parameters:
11.10 Detention Practices
11.10.1 Detention Practices are storage practices that are explicitly designed to provide stormwater detention for the Conveyance Event, Cv (10-year) and Flooding Event, Fv (100-year). Design variants include:
11.10.1.1 Dry Detention Pond
11.10.1.2 Dry Extended Detention (ED) Basin
11.10.1.3 Underground Detention Facilities
11.10.3 Detention Practices Feasibility Criteria
11.10.3.1 Depth-to-Water Table and Bedrock.
11.10.4 Detention Practice Conveyance Criteria
11.10.4.1 Principal Spillway
11.10.4.2 Non-Clogging Outlet
11.10.4.4 Emergency Spillway.
11.10.4.5 Inflow Points.
11.10.5 Detention Practices Pretreatment Criteria
11.10.5.1 A forebay must be located at each major inlet to trap sediment and preserve the capacity of the main treatment cell. The following criteria apply to forebay design:
11.10.6 Detention Practices Design Criteria
11.10.6.2 Detention Practice Sizing.
11.10.6.4 Retaining walls around Dry Detention Ponds and Dry ED Basins shall be limited to no more than 50% of the pond perimeter based upon the peak elevation of the Cv. In order to maintain the safety requirements, retaining walls shall be configured as follows:
11.10.6.5 Safety Features
11.10.6.6 All Detention Practices shall be designed so as to be accessible for maintenance.
11.10.6.6.3 Maintenance access must meet the following criteria:
11.10.6.7 Maintenance Set-Aside Area
11.10.7 Detention Practices Landscaping Criteria
11.10.8 Detention Practices Construction
11.10.8.3 Use of Dry Detention Pond or Dry ED Basin for Erosion and Sediment Control.
11.10.8.3.4 The Sediment and Stormwater Plan must include conversion steps from sediment basin to permanent Dry Detention Ponds and Dry ED Basins in the construction sequence.
11.10.8.4 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.10.8.5 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the Detention Practice has been constructed within allowable tolerances and in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency.
11.10.8.5.1 Allowable tolerances for Dry Detention Pond and Dry ED Basin are as follows:
11.10.8.5.2 Allowable tolerances for Underground Detention Facilities are as follows:
11.10.9 Detention Practices Maintenance Criteria
11.11 Stormwater Filtering Systems
11.11.1 Stormwater Filter Systems are practices that capture and temporarily store the design storm volume and pass it through a filter media or material. Filtered runoff may be collected and returned to the conveyance system, or allowed to partially infiltrate into the soil. Design variants include:
11.11.4 Stormwater Filtering Systems Stormwater Credits
11.11.4.2 Stormwater Filtering Systems sized in accordance with the design criteria shall receive the following pollutant reduction performance credits:
11.11.5 Stormwater Filtering Systems Feasibility Criteria
11.11.5.1 Depth to Water Table and Bedrock
11.11.6 Stormwater Filtering Systems Conveyance Criteria
11.11.8 Stormwater Filtering Systems Design Criteria
11.11.8.2 Filter
11.11.8.3 Underdrain
11.11.8.4 All Stormwater Filtering Systems must be designed so as to be accessible for maintenance.
11.11.8.4.3 Maintenance access must meet the following criteria:
11.11.10 Stormwater Filtering Systems Construction Criteria
11.11.10.1 Erosion and Sediment Control.
11.11.10.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.11.10.3 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the stormwater filtering system has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for stormwater filtering systems are as follows:
11.12 Constructed Wetlands
11.12.1 Constructed Wetlands are practices that mimic natural wetland areas to treat urban stormwater by incorporating permanent pools with shallow storage areas. Constructed Wetlands may provide stormwater detention for larger storms (Cv and Fv) above the RPv storage. Design variants include:
11.12.2 Constructed Wetland Stormwater Credits
11.12.2.1 Traditional Constructed Wetlands Performance Credits
11.12.2.2 Wetland Swale Performance Credits
11.12.2.2.1 Wetland Swales receive the following runoff reduction credits:
11.12.2.3 Ephemeral Constructed Wetland Performance Credits
11.12.2.3.1 Ephemeral Constructed Wetlands receive the following runoff reduction credits:
11.12.2.4 Submerged Gravel Wetland Performance Credits
11.12.4 Constructed Wetland Conveyance Criteria
11.12.4.1 Principal Spillway
11.12.4.4 Inflow Points
11.12.5 Constructed Wetland Pretreatment Criteria
11.12.5.4 The following criteria apply to forebay design:
11.12.6 Constructed Wetland Design Criteria
11.12.6.2 Constructed Wetlands shall be designed so that they will:
11.12.6.4 Liners
11.12.6.4.2 When the geotechnical engineer recommends a liner, acceptable options include the following:
11.12.6.4.2.1 A clay liner having a minimum compacted thickness of six inches with an additional six inch layer of engineered wetland soil mix containing a minimum of 35% organic material above it. Clay used as a liner must meet the following specifications:
11.12.6.5 Trash Racks.
11.12.6.7 Safety Features
11.12.6.8 All Constructed Wetlands must be designed so as to be accessible for maintenance.
11.12.6.8.3 Maintenance access must meet the following criteria:
11.12.6.9 Maintenance Set-Aside Area
11.12.6.10 Traditional Constructed Wetlands
11.12.6.10.5 Flow Path
11.12.6.10.6 Traditional Constructed Wetlands shall be composed of the following zones:
11.12.6.10.6.1 Zone 1: Deep Pools.
11.12.6.10.6.2 Zone 2: Transition Zone.
11.12.6.10.6.3 Zone 3: Low Marsh Zone.
11.12.6.10.6.4 Zone 4: High Marsh Zone.
11.12.6.10.6.5 Zone 5: Floodplain.
11.12.6.11 Wetland Swales
11.12.6.11.1 Wetland Swale Sizing.
11.12.6.12 Ephemeral Constructed Wetlands
11.12.6.12.1 Ephemeral Constructed Wetland Sizing.
11.12.6.13 Submerged Gravel Wetlands
11.12.6.13.1 Submerged Gravel Wetland Sizing.
11.12.6.13.2 Gravel substrate.
11.12.6.13.5 Underdrain.
11.12.7 Constructed Wetland Landscaping Criteria
11.12.8 Constructed Wetland Construction
11.12.8.2 The Sediment and Stormwater Plan must include conversion steps from sediment basin to permanent Constructed Wetlands in the construction sequence.
11.12.8.3 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.12.8.7 Upon facility completion, the owner shall submit Post Construction verification documents to demonstrate that the Constructed Wetlands has been constructed within allowable tolerances in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for Constructed Wetlands practices are as follows:
11.12.9 Constructed Wetland Maintenance Criteria
11.13 Wet Ponds
11.13.1 Wet Ponds are stormwater storage practices that consist of a combination of a permanent pool, micropool, or shallow marsh that promote a good environment for gravitational settling, biological uptake and microbial activity. Wet Ponds are widely applicable for most land uses and are best suited for larger drainage areas. Runoff from each new storm enters the wet pond and partially displaces pool water from previous storms. The pool also acts as a barrier to re-suspension of sediments and other pollutants deposited during prior storms. When sized properly, Wet Ponds have a residence time that ranges from many days to several weeks, which allows numerous pollutant removal mechanisms to operate. Wet Ponds can also provide storage above the permanent pool to help meet stormwater management requirements for larger storms. Design variants include:
11.13.1.1 Wet Quantity Management Pond
11.13.1.2 Wet Extended Detention (ED) Pond
11.13.3 Wet Pond Feasibility Criteria
11.13.4 Wet Pond Conveyance Criteria
11.13.4.1 Principal Spillway
11.13.4.4 Inflow Points
11.13.5 Wet Pond Pretreatment Criteria
11.13.5.2 The following criteria apply to forebay design:
11.13.6 Wet Pond Design Criteria
11.13.6.7 Retaining walls
11.13.6.7.2 In order to maintain the safety requirements, retaining walls shall be configured as follows:
11.13.6.8 Liners
11.13.6.8.2 When the geotechnical engineer recommends a liner, acceptable options include the following:
11.13.6.8.2.1 A clay liner having a minimum compacted thickness of 12 inches with an additional 12 inch layer of compacted soil above it. Clay used as a pond liner must meet the following specifications:
11.13.6.9 Trash racks shall be provided for low-flow pipes and for all riser structure openings.
11.13.6.12 Safety Features
11.13.6.13 All Wet Ponds must be designed so as to be accessible for maintenance.
11.13.6.13.3 Maintenance access must meet the following criteria:
11.13.6.14 Maintenance Set-Aside Area
11.13.7 Wet Pond Landscaping Criteria
11.13.7.2 A planting plan must be provided that indicates the methods used to establish and maintain vegetative coverage in the Wet Pond and its vegetated perimeter. Minimum elements of a planting plan include the following:
11.13.7.2.3 Size and spacing of plant material or application rate of seed mixes, as applicable.
11.13.8 Wet Pond Construction
11.13.8.1 Use of Wet Ponds for Erosion and Sediment Control
11.13.8.1.3 The Sediment and Stormwater Plan must include conversion steps from sediment basin to permanent Wet Pond in the construction sequence.
11.13.8.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.13.8.4 Upon facility completion, the owner shall submit post construction verification documents to demonstrate that the wet pond has been constructed within allowable tolerances and in accordance with the approved Sediment and Stormwater Management Plan and accepted by the approving agency. Allowable tolerances for wet pond practices are as follows:
11.13.9 Wet Pond Maintenance Criteria
11.14 Soil Amendments
11.14.2 Soil Amendment Stormwater Credit Calculations
11.14.2.1 Soil Amendments receive the following runoff reduction performance credits. Runoff reduction allowances are applied to the amendment area only.
11.14.2.1.1 The RPv runoff reduction performance credit for Soil Amendments is based upon the hydrologic soil group (HSG) of the existing soil:
11.14.3 Soil Amendments shall not be applied where:
11.14.4 Soil Amendment Design Criteria
11.14.4.1 Soil testing shall be conducted during two stages of the Soil Amendment process.
11.14.4.3 When Soil Amendments are used within the footprint of a BMP such as sheet flow to filter strip, sheet flow to open space, or vegetated channels to adjust the hydrologic soil group of the amended area and receive the runoff reduction performance credits for those BMPs, the following criteria apply:
11.14.5 Soil Amendment Construction Criteria
11.14.5.1 For compost incorporation depths up to 12 inches:
11.14.5.2 For compost incorporation depths 12 inches or greater:
11.14.5.2.1 The proposed amendment area shall be excavated to the required incorporation depth, as follows:
11.14.5.2.2 Amended soil shall be returned to the soil amendment area as follows. The number of lifts may vary depending on the capabilities of the equipment being used, but a minimum of two lifts is required.
11.14.5.3 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.15 Proprietary Practices
11.15.2 Proprietary Practices Stormwater Credit Calculations
11.15.5 Proprietary Practice Design Criteria
11.15.5.2 All Proprietary Practices must be designed so as to be accessible for maintenance.
11.15.5.2.3 Maintenance access must meet the following criteria:
11.15.7 Proprietary Practice Construction Sequence
11.15.7.2 Construction reviews are required during the following stages of construction, and shall be noted on the plan in the sequence of construction:
11.16 Source Controls
11.16.2 Design variants for Source Controls include:
11.16.3 Source Controls Stormwater Credit Calculations
11.16.3.2 Nutrient Management receives the following pollutant reduction credits:
11.16.3.3 Street Sweeping receives the following pollutant reduction credits:
11.16.4 Source Controls Design Summary
11.17 Afforestation
11.17.1 Afforestation includes practices that mimic the hydrologic benefits of a natural forest utilizing a regeneration process within the landscape by selectively planting tree seedlings (less than one inch DBH) or saplings (greater than one inch DBH). Afforestation can be used as both a runoff reduction practice by converting non-forested areas to forested areas as well as a mitigation practice for offsetting the clearing of forested areas during the development process. Design variants for afforestation include:
11.17.2 Afforestation Design Criteria
11.17.3 Afforestation Landscaping Criteria
11.17.4 Afforestation Construction Sequence
11.17.5 Afforestation Maintenance Criteria
12.1 Soil Investigation Procedures for Stormwater Best Management Practices (BMPs)
12.1.2 General Soil Investigations
12.1.2.2 Soil Characterization
12.1.2.2.1 The minimum number of borings or pits shall be conducted for each BMP as follows:
12.1.3 Infiltration Testing Procedures
12.1.3.1 Planning and Design Phase
12.1.3.1.3 An initial screening of readily available data is required to determine feasibility of infiltration practices. Screening shall include at a minimum:
12.1.3.1.5 Field Permeability Testing shall be done in accordance with ASTM-D5126 "Comparison of Field Methods for Determining Hydraulic Conductivity in the Vadose Zone".
12.1.3.1.6 The minimum number of field measured infiltration tests are based on the proposed facility's dimensions as follows:
12.1.3.1.8 After the saturation period, a minimum of two (2) test periods, are required. or until at least two (2) consecutive test periods are consistent. Each test period shall have a maximum reading interval of 15 minutes and meet one (1) of the following criteria:
12.1.3.1.8.3 A stabilized infiltration rate as defined below:
12.1.3.2 Construction Phase
12.1.4 Soil Investigation for Embankments
12.1.4.2 Site Investigation
12.1.4.2.1 The soil investigation for the embankment plan shall include the following:
12.1.4.3 Methods of Subsurface Exploration
12.1.4.3.2 Minimum Number of Explorations
12.1.4.3.3 Minimum Depth of Explorations
12.1.5 Soil Investigation Report
12.1.5.1 Soil investigation reports shall include the following:
12.1.5.1.5 Borehole or test pit logs must provide the following information:
12.1.5.1.12 Geotechnical recommendations for structural earthwork shall include:
12.1.5.2 Infiltration test reports shall include the following:
12.1.5.2.3 Infiltration test log must state:
12.1.5.2.5 Geotechnical recommendations shall be provided for each stormwater management facility, including design infiltration rate, impact of infiltration on adjacent facilities, effect of infiltration on slope stability, if the facility is located on a slope, stability of slopes within the facility, and foundation bearing resistance.
12.1.5.3 Geotechnical reports for embankments shall include the following:
12.1.5.3.4 Design recommendations for embankment construction shall identify the following actions:
12.2 Setbacks
12.2.3 Horizontal setback distances for all applicable best management practices (BMPs) shall be shown on the design plans with dimensions. The setback distances shall be measured from the BMP's water surface elevation for the Cv event to the following:
12.2.4 Applicable Setbacks
12.2.4.1 Public and Domestic Wells
12.2.4.1.4 In cases where the 100-foot setback cannot be met for a domestic well, the Department or Delegated Agency may consider an alternative method of compliance (AMC). The AMC shall consist of the following:
12.2.4.1.4.5 All tests of groundwater shall monitor for the following constituents:
12.2.4.1.5 The minimum setback distances for domestic wells with alternative method of compliance from applicable BMPs are as follows:
12.2.4.1.5.1 For Infiltration Practices, Bioretention, Permeable Pavement Systems, Constructed Wetlands and Wet Ponds into the water table:
12.2.4.1.5.2 For Detention Practices and Wet Ponds above the water table:
12.2.4.2 Septic Systems
12.2.4.2.2 The minimum setbacks for septic system drainfields and components from applicable BMPs shall be as follows
12.2.4.4 Buildings and Structures
13.1 Stormwater Management Offset Provisions
13.1.1 For the purpose of achieving project compliance, a stormwater management offset may be used as an alternative method to full or partial compliance with one or both of the following:
13.1.2 A stormwater management offset may be used as an alternative to full or partial compliance on projects that:
13.2 Stormwater Management Fee-in-lieu
13.2.1 Owner Responsibilities
13.3 Stormwater Management Trading
13.4 Stormwater Management Banking
13.4.3 Stormwater Management Bank Owner Responsibilities
13.4.4 Department or delegated agency responsibilities.
13.5 Stormwater Management Offset District
13.5.3 The intent of the Stormwater Management Offset District must be clearly defined regarding program components. Those components must include:
7 DE Reg. 1147 (03/01/04)