A. Introduction B. Important New Definitions C. New Triggers for SWM and SC D. Changes to Permitting Procedures and Fees E. Design Issues F. SWM Alternatives G. Changes to Monetary Contribution Process H. Transition Policies Appendix - Summary of Major Changes from Existing Law and Regulations A. INTRODUCTION This is a brief review of new features and procedural changes in Chapter 19 of the Rockville City Code and the accompanying Regulations for sediment control and stormwater management (SWM). The Mayor and Council adopted these revisions on September 9, 2002, and the new requirements took effect immediately upon adoption. Please refer to the complete text of the ordinance and Regulations for more detail. The Department of Public Works (DPW) staff continues to review the new State and City SWM standards, and will implement additional procedural changes as we update our computerized permit tracking system. New application forms for sediment control and SWM permits will be introduced in October. DPW anticipates having a separate SWM permit numbering and tracking system in place by the end of 2002. Until then, staff will continue to issue a combined SWM and sediment control permit (the current SCP permit). New forms and information will be available on the City's website (ci.rockville.md.us) B. IMPORTANT NEW DEFINITIONS Design Manual - Maryland Department of Environment's (MDE) SWM Design Manual. It and the SWM control terms (CPv, WQv, Qp, Recharge) and standards are incorporated into the law. Improved single-family residential lot - any residential lot containing one single-family detached house, townhouse, or duplex that wants to make an addition or improvement to the lot or the house. This does not include vacant lots or a lot with a house that is being demolished and replaced with a new house. Generally, any project requiring an SFD (Single Family Detached) or DEM (Demolition) permit from the City's Inspection Services Division will also need to address SWM. Non-structural SWM practice - these are the non-structural practices listed in Chapter 5 of the Design Manual, which may be used to reduce the SWM volumes required for a project. If the proposed practice doesn't meet the design criteria listed for that practice in the Manual, it cannot receive SWM credit for it. Redevelopment - any alteration (grading, construction, improvement) on sites with existing and completed commercial, industrial, institutional or multi-family residential land uses. In accordance with MDE's requirements, redevelopment does NOT include single family detached or townhouse development that is being redeveloped, regardless of the new land use. This will count as new development. C. NEW TRIGGERS FOR SWM AND SEDIMENT CONTROL The triggers for SWM and sediment control have been adjusted to match the current State requirements and to reflect the City's need to regulate the small-scale development common to Rockville. SWM and sediment control permits are also required whenever work is done near streams, in order to enforce appropriate protection for the environmentally sensitive stream buffer area. For more details, see the Regulations, Article II.Division 1.A., Activity Subject to Provision of SWM, and Article III.Division 1.A, [Sediment Control] When Required. SWM shall be addressed for all new development or redevelopment that: involves 5,000 square feet or more of disturbed area; or creates or replaces 2,000 square feet or more of impervious area on an improved single-family residential lot (see definition above); or creates or replaces any amount of impervious area on property other than an improved single-family residential lot; or requires a federal or state authorization for work in a floodplain, wetland or wetland buffer, or waterway. Answers to SWM Trigger FAQs: Milling or overlaying of existing paving does not get included in calculating disturbed area or impervious creation. DPW's policy is that if the ground/sub-base is not exposed, then the work does not trigger SWM. An improved single-family residential lot may add up to 2,000 square feet of imperviousness through additions, adding a second story, replacing a roof, patios, driveway expansions, garages, road cuts, pools, etc. Impervious area calculation includes the new impervious area even if it is replacing existing impervious area. This is true even if the project actually reduces the overall amount of imperviousness from existing conditions. The City's 50% rule for SWM is still in effect. If 50% or more of the site is disturbed, SWM must be provided for all imperviousness within the site that is not already treated by current standards. If less than 50% of the site area is disturbed, only address SWM for whatever is created through the project (and for the right-of-way contiguous to the project). See the Regulations, Article II.Division 1.B., SWM Required, to interpret which part of the ROW should be included for unusual cases such as corner lots, cul de sacs, and redevelopment. A Sediment Control Permit (SCP) is required for land disturbing activity that involves: (Major Land Disturbing Activity) - 5,000 square feet or more of disturbed area or 100 cubic yards or more of grading; or (Environmentally Sensitive Areas) - area within a stream buffer as defined in the City's Environmental Guidelines; or (Small Land Disturbing Activity Resulting in a New Building) - less than 5,000 square feet of disturbed area/100 cubic yards grading BUT creates a new house or other building. Decks, patios, small additions, sheds, and minor commercial work do not require an SCP. The Regulations now include sections on SCP issuance for rough grading and for a builder's SCP. DPW instituted procedures for these categories in 1997. D. CHANGES TO PERMITTING FEES AND PROCEDURES Fee Changes Permit fees are described in the Mayor and Council Resolution 17-02. Fee amounts have not been changed. The Regional Participation Application Fee has been eliminated. This is replaced by charging a single SWM Concept Fee for every SWM case, regardless of whether the case is for on-site SWM, alternate SWM improvements, monetary contribution, or a combination approach. No SWM Concept fee is charged to individual single family residential lots that are not part of a larger development. The same fee schedule applies as before for all aspects of SWM and sediment control. Two clarifications for determining the fees: the SWM Concept Fee is now based on site area, not drainage area. This simplifies the situation where one site has several SWM facilities of different drainage areas. Builder's SCP Permit Fee is still $100 per house. This now covers any kind of building, including a house. New Procedures This is a brief summary of the submittal and approval procedures. Refer to the Regulations for a complete description. 1. SWM Concepts All applicants who meet the SWM triggers must submit a SWM Concept application package. See the submittal requirements in the Regulations. Use of SWM alternatives, including monetary contribution, must be requested in writing and approved as part of the concept. Enough details and justification should be included to clearly show what's being requested and why. DPW will now sign the approved concept plans, as well as issuing a SWM Concept approval letter.   2. SWM Permits All applicants must submit a SWM Permit application package. See the Regulations for all items required for a complete submittal. If the approved SWM concept is solely for monetary contribution, only a simplified application package is required. It should include detailed site plans showing the final impervious area for the purpose of confirming the monetary contribution amounts, and any other information requested by DPW to address drainage issues or other concerns. See Monetary Contribution Procedures later in this guide for more details. The submittal must include a brief narrative and a data table describing all SWM measures, their drainage areas, and what they control (i.e., WQv, Recharge, CPv, etc.). If non-structural SWM measures are proposed, confirm that they will work with proposed grading and whether they meet the Design Manual criteria. If not, the SWM facilities/monetary contributions must be adjusted accordingly. These areas should also be shown on the drainage area map and clearly labeled. A drainage area map that shows all structural and non-structural SWM features and each feature's drainage area boundary is required. Wherever possible, keep all structural and non-structural SWM features outside of private residential lots, especially grass swales and bioretention. At its discretion, DPW may require amendment of the approved SWM Concept if design standards have changed between the concept approval and engineering plan approval, or if the concept is substantially modified in the engineering plans. 3. SWM Security for Functional Landscaping in SWM Facilities (i.e., wetland marshes & bioretention) There is now a provision for landscaping to be inspected during the planting, and at least once each growing season for 2 years after planting to verify a survival rate of 75% or better. This means that a portion of the SWM security (bond or letter of credit) must be retained for 2 years after the planting is done. For these cases, DPW will now ask that two SWM securities be submitted - one for the construction of the facility and the second solely for the cost of necessary landscaping/pondscaping. The first security will be released upon satisfactory completion of the SWM construction, and the second will be held until the landscaping is established. E. DESIGN ISSUES CPv Orifice Size - The Channel Protection Volume, or CPv (i.e., 1-year, 24-hour ED) discharge rate, which is a function of both imperviousness and drainage area, gets very small in small drainage areas and/or low impervious sites. This generates a small orifice size, which creates a concern about clogging by trash, leaves, sediment, etc. All low flow pipes or orifices shall be designed to avoid clogging, using features such as reverse-slope piping or acceptable trash racks, such as the expanded metal trash racks in the Design Manual. If the computations result in an orifice diameter of less than 2", then the City's minimum orifice diameter of 2" shall be used instead of the calculated orifice opening. (This will still fully meet the CPv control requirement.) CPv Required for Small Sites - The City requires CPv to be addressed for all developments that meet the SWM triggers, regardless of the project size or whether the one-year post development peak discharge is less than or equal to 2.0 cubic feet per second (cfs). This differs from Section 2.3 of the MDE Design Manual. The City generally does not require a SWM facility to be built to control the CPv in cases where this discharge is less than or equal to 2 cfs, but still requires a monetary contribution for quantity control in lieu of providing a facility. Recharge - Recharge is required on all sites, per MDE's direction. However, the Regulations list a number of reasons that it may be omitted (see Article II, Division 3.B., Recharge.) DPW has several other policies for recharge: If the soil delineation is unclear in the soil survey or if a hydrologic soil group is not assigned to a specific soil, the default hydrologic soil group for recharge design is "B". Soil types are grouped hydrologically in the Soil Survey of Montgomery County Maryland, Natural Resources Conservation Service, July, 1995. All structural recharge BMPs shall be sited outside of Hydrologic Soil Group 'D' soils, based on the Montgomery County Soil Survey. Recharge drainage areas and the recharge BMPs themselves must be within the same drainage area as the stormwater facility receiving credit for the recharge volume reduction. Fill areas are unsuitable for recharge unless the bottom of the recharge storage area is at least three (3) feet below the original ground elevation. Bioretention or surface sand filters may serve as recharge features if the bottom is over-excavated and backfilled with clean stone below the invert of the required underdrain. (No filter cloth or geotextile on the bottom, just on the sides of the excavation.) The void space volume below the underdrain should correspond with the required recharge volume for that drainage area. No soil tests or groundwater elevation tests are required to prove percolation rates if the intention is recharge. If the entire water quality facility is supposed to be an infiltration-based practice, then soils perc tests, etc, are needed. F. SWM ALTERNATIVES SWM alternatives are defined as measures approved by the City in lieu of on-site SWM to provide equivalent SWM benefits or mitigate the effects of uncontrolled stormwater. This can include stream restoration, storm drain outfall stabilization at or near a stream channel, retrofit of an existing SWM facility either on or off the subject site, or pilot projects approved by DPW and MDE to test new SWM techniques. Monetary contributions are also SWM alternatives, and may be used where an equivalent project cannot be identified, or for smaller sites where it would be unreasonable to mobilize for a construction project. Some considerations for SWM alternatives are: The goal is to match a development project with an alternative that is monetarily equivalent to the cost of building an on-site SWM facility needed to meet the SWM obligation. This may exceed the cost of the monetary contribution for the project. Developers may propose their own alternative project, or DPW may suggest one. Use of a SWM alternative may be acceptable for redevelopment or infill sites even if on-site SWM is feasible, because the watershed value of on-site SWM for one small site surrounded by uncontrolled sites typically is minimal. However, this is dependent on the scale of the redevelopment project, surrounding conditions and receiving stream conditions, among other issues. ·Use of a SWM alternative is not automatic. DPW must first determine whether on-site SWM is feasible. This is still the City's first preference in new development situations. G. CHANGES TO THE MONETARY CONTRIBUTION PROCESS         (FORMERLY SWM WAIVER) Rates: The Quantity control rate is still $40,000 per impervious acre. It may be broken into two types: CPv (i.e., 1-year, 24-hour control) and Overbank Flood Protection (i.e., 10/10 control). If the developer can justify providing only one or the other (such as because of site constraints, or only one is possible or necessary), then a contribution may be accepted for either CPv or Overbank Flood Protection, whichever can't be provided, at $20,000 per impervious acre. The Quality control rate increases to $12,000 per impervious acre. This includes Recharge volume. A developer cannot reduce this quality rate by providing recharge only. Monetary Contribution Procedure: The previous system of SWM waivers (also known as Regional Participation requests) that involved the City Manager and Mayor and Council approvals has been eliminated. A monetary contribution is now considered to be an alternate method for meeting a development's SWM obligation. A monetary contribution request will be handled through the standard SWM Concept and Permit process by the DPW reviewer. Applicant fills out SWM Concept application form, and indicates on this whether concept is for on-site SWM, SWM alternative, or SWM monetary contribution (may choose any combination of these). There is no separate monetary contribution request form. The Regulations require the SWM Concept submittal to include written justification for the proposed use of a SWM alternative (may be within the cover letter or within a SWM Concept booklet). This justification must explain why standard on-site SWM is not being used and why the proposed alternative is appropriate to the scale of the development project. Staff reviews submittal and decides on acceptable and appropriate method(s) to meet SWM obligation. Use of SWM alternatives is limited to specific circumstances listed in the Regulations, Article II, Division 2, B. Generally, alternatives are appropriate where: the site drains to an updated regional SWM facility for quality and/or quantity control; feasible on-site SWM is less beneficial to the watershed than an alternative. Note that this condition applies only to redevelopment or infill sites; on-site SWM is not reasonably able to be implemented (site constraints, no techniques will work that meet the SWM Manual requirements, site is too small to support a SWM feature, etc.). Staff issues SWM Concept approval letter to applicant. The letter will contain: the name of the project, the legal description (i.e., Subdivision/lot/block or parcel number), and the assigned SWM Permit number; description of the SWM measures approved for the project, including any alternatives; f monetary contribution has been approved, an estimate and breakdown of the amount (i.e., quality cost, quantity cost, and the impervious acres for each type) Applicant proceeds to SWM Permit stage and submits a permit application and all required submittals. If the sole method needed for the site is a SWM monetary contribution, then the only submittal requirement is the application, a detailed site plan showing final impervious acreage for use in confirming the contribution amount, and any other information DPW may need. (Since impervious areas may change from concept through final design, the final contribution amount is determined prior to SWM Permit issuance based on the final plans, not on the Concept-level plans.) Staff sends the applicant a letter directing payment of contribution. Contribution must be paid before issuance of related SWM permit. For cases with only monetary contributions, DPW issues a SWM Permit without attached plans (unless reviewer requires them, such as to show drainage improvements) and will not distribute the permit to the inspector. This SWM permit must be issued before issuance of any related PWK permit for the project and before release of any building permit. Previous Monetary Contributions: Sites that previously received a SWM waiver (i.e., Regional Participation) approval will still need to undergo SWM Permit review for new development or redevelopment. In cases where a previous SWM waiver was granted: The applicant should determine which part of the site was covered by the previous waiver, which type of waiver it was (quality, quantity or both), and the contribution rate. Please submit any available plans and/or letters to document previous waivers and payments. Any proposed imperviousness not covered by the old waiver shall pay a contribution at the current rate. Any proposed imperviousness on the previously waived area will fall in one of these categories: required to have on-site SWM, if the City determines that this is practical and appropriate; the developer may provide a regional SWM project or watershed project (i.e., one of the SWM alternatives); if monetary contribution is still considered appropriate for this area, developer will either pay the difference between the previous waiver's rate and the current rate or pay nothing if the contribution rate is the same as under the previous waiver's rate. If new on-site SWM or a SWM alternative project is required, no credit will be given for previous contributions. H. TRANSITION POLICIES Effective Date All provisions of the ordinance and regulations are effective as of Sept. 10, 2002, for any projects that have not received SWM or sediment control permits. As of Jan. 1, 2002, all developments under review have been designed using the State's new standards. Permits recently issued under the old SWM standards are allowed the customary two-year permit period to complete construction. However, there will be no SCP or SWM permit extensions given after the two-year period for permits issued under the old SWM standards. Monetary Contribution Transition Procedure Sites that have not yet paid their SWM monetary contributions must now pay at the new rate of $12,000 per impervious acre for quality. (The quantity contribution rate is unchanged.) If a SWM waiver contribution was previously approved but has not yet been paid, the contribution must be re-calculated using the new contribution rates. Future Impervious Construction Deadline MDE has informed the City that all impervious areas constructed after July 1, 2004, must be served by SWM that meets the new standards, or must provide an appropriate SWM alternative. Impervious areas which are served by SCPs using the old SWM design standards must be built by July 1, 2004. The City permits imperviousness through PWK permits (for streets and sidewalks) and building permits (for buildings and some private parking associated with buildings). The PWK permits expire after six months, but building permits do not - they simply are continued by Inspection Services as long as the job is actively under construction. To meet the intent of MDE's deadline, DPW will not issue PWK permits after December 31, 2003, for sites that are served by the old SWM standards. Building permit sign-offs by DPW for projects under the old SWM requirements may be limited after this date to ensure that adequate time remains to complete construction before the cutoff. Applicants who fail to obtain their PWK permits by this date or do not complete the construction by July 1, 2004, must provide any additional SWM measures needed to bridge the gap between their existing SWM provisions and the new requirements. This could be met in several ways - by upgrading an on-site SWM system, if feasible, by providing a SWM alternative (such as upgrading a comparable SWM system elsewhere or repairing an eroded storm drain outfall) or by paying a monetary contribution calculated for the difference. This will affect relatively few cases, typically phased developments that obtained SCPs for SWM in 2001 to cover the whole site, but are spreading out the building/parking construction over many years. DPW will send out periodic notices to applicants in 2003 who may be affected by this deadline. If you or your client are engaged in long-term developments, please factor this in to your construction schedule. APPENDIX - MAJOR CHANGES TO THE CITY'S SWM AND SEDIMENT CONTROL REQUIREMENTS FROM THE PREVIOUS ORDINANCE/REGULATIONS Required changes from MDE: MDE's SWM requirements bring all counties and municipalities into conformance with accepted SWM standards of design and watershed protection, and also offer flexibility to deal with site-specific conditions and varying watershed protection goals. Some of the important changes required by MDE to the City's existing standards are described below. Changes to Water Quality Treatment Requirements: Previous: Although the previous Code did not specifically require stormwater management for water quality, developers have been required to provide water quality measures since the late 1980s. The regulations list four general SWM methods (infiltration, open vegetated swales and depressions, retention and detention structures), but there are no standards or performance criteria for acceptable water quality treatment, and no discussion of the water quality control goals. Revision: - Requires specific methods for water quality treatment that meet the State's required pollutant removal rates. - Requires groundwater recharge where feasible to maintain baseflow in streams and natural wetlands. - Use of proprietary water quality devices (that aren't approved as stand-alone water quality treatment by MDE) is limited to redevelopment sites or as part of a 'treatment train' due to pollutant removal limitations. Adoption of Unified Sizing Criteria for SWM facilities: Previous: The previous Code required 10/2 SWM quantity control (i.e., storage of post-developed runoff for the 10-year storm to be released at the pre-developed 2-year storm discharge rate). The regulations listed several sizing criteria for water quality, including treatment of ½" of runoff over the drainage area. All of these criteria have been replaced by MDE. Revision: - Allows use of non-structural practices and site layout elements that cause runoff to be filtered through vegetation and/or infiltrated into the ground in open areas, thus reducing required SWM treatment volumes - Adopts the 1-year, 24-hour Extended Detention discharge rate for water quantity control to reduce downstream erosion problems. (The City implemented this as an interim quantity control standard in 1996 to replace the outdated 10/2 standard from 1978.) - Adopts treatment of roughly one inch of runoff over the impervious area for water quality control. This doubles the City's existing requirement of treatment volume. SWM Program Changes Previous: The previous SWM triggers only included creation of impervious area, not disturbed area criteria, which is now required by MDE. The Code and regulations contained extensive sections on SWM design, which were out of date. The previous regulations listed only infiltration, open vegetated swales and depressions, retention and detention structures, in that order, as accepted SWM methods without regard to site conditions, and do not reference more recent SWM methods. The regulations also listed conditions for approval of a waiver from on-site SWM; these conditions were updated to meet the State requirements for alternatives to on-site SWM. Revision: - SWM 'hierarchy' of preferred methods is replaced by a menu of equal SWM water quality techniques designed to fit site constraints. - SWM must be addressed when a project disturbs 5,000 square feet or more. - Specifies when a SWM alternative to on-site SWM may be considered; permissible circumstances now include redevelopment and infill projects, and practical limitations. - Adopts the MDE Stormwater Management Design Manual by reference in the City Code. - The City has meet MDE requirements to adopt and implement the state's changes. MDE has also stated that all impervious areas constructed after July 1, 2004, must be served by SWM that meets the new standards, or must provide an appropriate SWM alternative. The City will enforce this through permit issuance controls in 2003 and 2004. Additional changes recommended by DPW: In addition, DPW made the following changes to the City's existing code and regulations to streamline processing, clarify policies, close loopholes and address other concerns raised by MDE. Most of these changes are procedural rather than content changes. Many of these items reflect existing policies that have developed over the last decade in the City, but were not mentioned in the previous ordinance or regulations. Stormwater Management Changes: Previous: The Sediment Control Permit (SCP) was the only formal approval step in the previous Code or regulations, and has served as the review and enforcement mechanism for SWM as well, which complicated processing and sometimes resulted in several SCPs being issued for the same site. The Code and regulations did not offer a mechanism to review stream restoration plans. The regulation's SWM triggers were confusing and sometimes led to efforts to piece-meal development to avoid SWM. The Mayor and Council simplified the SWM waiver process in 1995 (i.e., Mayor and Council review for creation of more than 0.2 acres of new imperviousness), then agreed in 2001 to change the waiver process to an administrative part of the SWM Concept review. Revision: - Establishes a new Stormwater Management Permit process, and incorporates the Stormwater Management Concept review process. - Changes the trigger for addressing SWM to include all impervious area construction except improvements to existing homes that create less than 2,000 square feet imperviousness. This will require all new development to address SWM, but will exempt secondary residential improvements such as additions, driveways, patios, etc. - Sets policies for SWM systems designed for multi-phase developments that have extended build-out periods. - Updates submittal requirements for SWM Concepts and SWM Permits and inspection requirements for SWM facilities. - Allows for stream restoration and other watershed structural improvements to be regulated by a SWM Permit. - Changes the SWM waiver process to an administrative SWM alternatives evaluation; monetary contributions and other in-kind improvements still accepted. - Strengthens the SWM monetary contribution policy for redevelopment that previously provided for SWM to require on-site SWM where appropriate or to require additional monetary contributions that make up the difference between the previous and current contribution rates. - Increases the SWM monetary contribution rate for quality control from $6,000 per impervious acre to $12,000 to reflect the doubling of the quality storage volume requirement. (This item is actually approved by a separate Mayor and Council resolution, but is also listed in the Regulations for informative purposes. Please refer to the latest version of the resolution for current contribution rates.) Sediment Control Changes: Previous: Under previous Code and regulations, the Sediment Control Permit also regulated SWM design, construction and enforcement. Sediment control was required in non-residential zones for any amount of disturbance; and in residential zones, for disturbed areas of 5,000 square feet or greater, or if creating 2,500 square feet or more of imperviousness, or where public improvements would be built or at risk from construction. In 1997, the Mayor and Council approved a sediment control fee schedule for rough grading and various levels of multi-phase construction, but the ordinance and regulations were not modified accordingly. Revision: - Separates the sediment control and stormwater management approval and enforcement functions. This will also facilitate tracking of SWM-related site and facility data. - Updates and simplifies the triggers for activities requiring a Sediment Control Permit. The new triggers will comply with State regulations by adding the trigger of 100 cubic yards or more of grading, and will also regulate sediment control on small sites in stream buffers or with new building construction. - Recognizes several categories of Sediment Control Permits necessary to phased construction.