Section 096-500-7 - Submissions and pre-application meetingsThis Section applies to Stormwater Management Law projects that do not qualify for a stormwater PBR.It also applies to Site Law projects. The applicant shall use the application form provided by the Department and include evidence that affirmatively demonstrates that the standards will be met, including information such as described in this Section.
A.Pre-application meetings. A pre-application meeting is required for a Stormwater Management Law project that does not qualify for a stormwater PBR, unless the requirement for such a meeting is waived by the Department based on an initial review of project plans and scope.A pre-application meeting between the applicant and the Department is an opportunity for the applicant to determine the statutory and regulatory requirements that apply to a specific project, and to identify the Department staff person who will serve as project manager for the application. A written request for a stormwater pre-application meeting must include two copies of a preliminary site plan, brief project description, and a regional map with the site marked.B.Design requirements. A design for a stormwater management system that includes any form of conveyance structure must be prepared under the supervision of, and dated, signed and sealed by, a professional engineer registered in the State of Maine, or a landscape architect licensed in the State of Maine, who by education, training, or experience is knowledgeable in stormwater management. Soil test data must be provided by a certified soil scientist, unless otherwise approved by the Department.C.Basic standards submissions. An erosion and sedimentation control plan or an inspection and maintenance plan for a project that does not qualify for a stormwater PBR must be prepared by a professional engineer registered in the State of Maine, landscape architect licensed in the State of Maine, or a Certified Professional in Erosion and Sedimentation Control. (1)Erosion and sedimentation control plan. Submit a plan showing designs for temporary and permanent stabilization measures for all disturbed areas within the project site and for all proposed stormwater management structures. Erosion and sedimentation control plan requirements are described in Appendix A of this Chapter. At a minimum, the erosion and sedimentation control plan must include the following: (a)Location plan. Submit a plan sheet or set of plans showing, at a minimum, the location of structures, disturbed land, pre-construction site topography, post-construction site topography, on-site or adjacent water resources, and all erosion and sediment control measures;(b)Site details. Submit a plan sheet showing the following: (i)Erosion and sedimentation control notes. Erosion and sedimentation control notes, must include, but not limited to, permanent stabilization measures, seeding and mulching rates, and a construction schedule with the proposed construction dates and timeframe for major earth moving and construction events; and(ii)Construction and installation details. Construction and installation details for erosion and sedimentation control measure must include, but are not limited to, sedimentation barriers, ditch lining, rip rap, and culvert inlet and outlet designs. NOTE: The Department has prepared protocols for the control of erosion and sedimentation. See "Maine Erosion and Sediment Control BMPs Maine Department of Environmental Protection."
(2)Inspection and maintenance plan. Submit a plan for the inspection and maintenance of the temporary and permanent erosion and sedimentation control measures for the project site as described in Appendices A and B of this Chapter: (a)List of measures. Submit a list of the erosion control measure and stormwater management measures to be inspected and maintained (e.g., "parking lot catch basins");(b)Inspection and maintenance tasks. Submit a list of inspection and maintenance tasks specific to each erosion control measure or stormwater management measure (e.g., "remove accumulated sediments in basin sumps"). Submit the specific qualifications of the person performing each task (e.g., "a professional engineer registered in the State of Maine will inspect the retention pond embankment");(c)Task frequency. Indicate the required frequency of each inspection and maintenance task (e.g., "accumulated sediments will be removed from all catch basins annually in early spring");(d)Responsible parties. Submit the name, job title, employer, employer address, phone number, and current email contact information for the person responsible for ensuring that inspection and maintenance tasks are completed. Submit the names, job titles, employer addresses, phone number, and any current email contact information of the engineers or other design professionals who designed the erosion control measures and stormwater management measures for the site. Include suppliers of proprietary erosion control measures or proprietary stormwater management measures used on the site;(e)Maintenance plan for detention basins or retention ponds. For each stormwater management pond or basin submit, at a minimum, an inspection and maintenance plan for the pond's embankments, outlet structure, and emergency spillway. Include as part of this plan provisions for the removal and disposal of accumulated sediments in the pond and the control of woody vegetation on the pond's embankments;(f)Maintenance plan for infiltration structures. For each infiltration structure, submit, at a minimum, an inspection and maintenance plan for the structure's pretreatment measures, embankments, surface lining, and overflow spillway. Include as part of this plan provisions for the removal and disposal of accumulated sediments in the structure and for the rehabilitation of clogged surface linings;(g)Maintenance plan for underdrained filters. For each underdrained filter, submit, at a minimum, an inspection and maintenance plan for the filter embankments, vegetation, underdrain piping, and overflow spillway. Include as part of this plan provisions for the removal and disposal of accumulated sediments in the structure, the rehabilitation of clogged surface linings, and the flushing of underdrain piping;(h)Maintenance plan for stormwater buffers. At a minimum, submit a plan for inspecting and maintaining the integrity and function of the project's stormwater buffers. As part of this plan, include provisions for the inspection, maintenance, and, if necessary, reconstruction of any level spreaders or ditch turnouts used to spread runoff into the buffers. Include as part of this plan provisions for the frequent removal and disposal of accumulated sediments and debris in the level spreader and turnout bays, provisions for the inspection and repair of any eroded areas within the buffer, and provisions for the reestablishment of buffer vegetation destroyed by post-construction activities;(i)Maintenance plan for manufactured stormwater treatment systems. For each manufactured system installed on the site, submit an inspection and maintenance plan for the system's inlet, treatment chamber(s), and outlet. The plan shall conform to the inspection and maintenance guidelines recommended by the manufacturer based on the estimated runoff and pollutant load expected to the system from the project. As part of this plan, include provisions for the frequent removal of accumulated sediments, debris, and contaminated waters from the system and, if applicable, provisions for the removal, disposal, and replacement of any clogged or spent filter media; and(j)Maintenance plan for ditches, culverts, and storm drains. Provide an inspection and maintenance plan for all stormwater conveyances to be built or installed on the site - including, but not limited to, ditches, swales, culverts, catch basins, and storm drain piping. As part of this plan, include provisions for the repair of eroded areas at the inlet, within, and at the outlet of each conveyance and include provisions for the frequent removal and disposal of accumulated sediments and debris at the inlet, within, and at the outlet of each conveyance.(3)Housekeeping. Submit a plan to address spill prevention, groundwater protection, fugitive sediment and dust, debris and other materials, trench or foundation de-watering, or non-stormwater charges, as applicable to the specific site. Housekeeping requirements are described in Appendix C of this Chapter.D. General and phosphorus standards submissions. A project required to meet the general standards or phosphorus standard must provide the following information and design specifications: (1)Narrative. A narrative describing site layout, and on-site and off-site watershed hydrology, including all new and existing buildings and facilities, which may be affected by the site runoff. Provide the total amount of disturbed area, impervious area, and developed area created by the project;(2)Drainage Plans. All topographic features, such as buildings and other facilities, drainageways, cover type, roads, drainage easements and subcatchment boundaries for pre-construction and post-construction conditions must be shown on a plan. Show all hydrologic flow lines and hydrologic soil groups boundaries on a plan and identify each subcatchment, reach, and pond. For post-construction conditions, show all new stormwater management structures and changes to the hydrologic drainage patterns; NOTE: Computer generated plans are recommended as hand-drawn plans can extend review time and delay approval.
(3)Calculations. The stormwater runoff calculations for measures designed to meet the general standards or phosphorus standard must be in accordance with acceptable engineering practice, including the following. (a)Water volume.The calculations used to determine the water volume needed to be filtered, infiltrated, or detained based on the proposed project must be provided;(b)Buffer sizing. Buffers used for runoff control must be sized according to requirements described in Appendix F of this Chapter; and(c)Calculation table and subcatchment plan. A table must be provided to show the sizing required and provided for each subcatchment area and treatment measure. A water quality plan must clearly show each treatment measure and subcatchment.(4)Submit a detailed log of at least one excavation or boring in the area of each proposed treatment measure.These excavations must extend to a depth of at least three feet below the lowest component (not lowest finished elevation) of the proposed structure and logs must include detailed information describing soil and overburden stratification, composition, texture, and other relevant characteristics, and elevation of seasonal high groundwater and bedrock, if encountered.(5)Details, designs, and specifications. The applicant must submit designs, construction details, and technical specifications for each stormwater management measure that will be constructed, installed, or managed on the site. (a)Wet Ponds. Submit a site plan and detail sheets having the following details and specifications for each stormwater management pond: a topographic plan view of the pond, a cross section of the pond embankment, a cross section and profile of the overflow spillway, soil test data, and specifications for constructing and stabilizing the pond's embankment. The peak storage depth required to meet the general standards must be shown on a cross section for each pond embankment. Submit a cross section of the gravel underdrain used to meet the standards. This cross section must specify the width and elevation of the pond bench, the thickness and gradation for the gravel drainage fill, and the diameter and material for the perforated underdrain pipe.(b)Vegetated soil filters. Submit a site plan and detail sheets having the following details and specifications for each vegetated soil filter bed: soil test data, a plan view of the filter area, a cross section of the embankment for the filter area at the overflow spillway, a cross section and profile of the overflow spillway, a cross section of the underdrain filter, the thickness and composition of the soil filter media, the thickness and gradation of the gravel drainage fill, the layout for the perforated underdrain pipe and the stabilization of the filter bed.(c)Infiltration. Submit a site plan and detail sheets having the following details and specifications for each infiltration measure: soil test data, a plan view of the infiltration structure, a cross section of the infiltration measure's runoff storage area, a cross section and profile of the structure's overflow spillway, and details and specifications for permanently stabilizing the infiltration area. The following information must be included, if required, asdescribed below: (i) Locations of any monitoring wells necessary for assessing the infiltration measure's performance or stormwater infiltration impacts on groundwater, surface irrigation sites, or subsurface wastewater disposal systems must be shown on the site plan;(ii) Location of any existing or proposed surface irrigation site, waste disposal site, subsurface wastewater disposal system, or other facility that could be impacted by operation of the infiltration system must be shown on the site plan;(iii) Location of any soil borings, test pits, or other explorations used to determine depth to groundwater, separation from bedrock, or other design information must be shown on the siteplan;(iv) Location of any water supply wells on-site or within 300 feet of the infiltration areas, zones of contribution for public water supply wells must be shown on the plan sheet;(v) Location of storage for any petroleum products, pesticides, fertilizers, road salt, hazardous materials, or other materials with the potential to contaminate groundwater must be shown on the site plan;(vi) Plans for management of any potential contaminants and soil sample analyses, such as a spill prevention, control, and countermeasure plan, must be submitted with appropriate supporting information; and(vii)Depth to the seasonal high groundwater table, depth to bedrock, and the thickness and composition of any liner used for restricting infiltration rates must be shown on the cross section view of the infiltration structure.(d)Buffers. Submit a topographic site plan showing the location of each buffer on the site, showing the layout of any berm level spreaders used to spread flows into each buffer, soil test data, and cover type within each buffer, and showing the land use and impervious and developed area draining to each buffer area. Provide a typical cross section for the berm level spreaders showing the geometry of the berm, the geometry of the upstream storage area, and the specifications for the berm material. Submit information demonstrating that the in slope fill material will have slopes no steeper than 3:1. Submit documentation, in the form of draft covenants and restrictions, demonstrating that buffer area(s) will be maintained as buffer. (6)Phosphorus export calculations. An application for a project using the phosphorus standard must include phosphorus export calculations. NOTE: The Department has prepared a protocol for determining phosphorous export. See "Phosphorus Control in Lake Watersheds,"Maine Department of Environmental Protection.
(7)Maintenance contract. Submit evidence demonstrating the ability to carry out inspection and maintenance of all stormwater treatment system structures, including any proprietary devices, or a signed contract with a qualified third-party to carry out inspection and maintenance requirements in accordance with plan requirements in Appendix B of this Chapter.E. Flooding standard submissions.(1)Control of peak flows. If a project must meet the flooding standard, the project must be designed to control the peak flows from the 2-, 10- and 25-year, 24-hour storms.(2)Details, designs, and specifications. The applicant must provide runoff curve number computations and time of concentration calculations for each subcatchment. Areas may qualify as subcatchments based on the characteristics of the site or the model used. The Department will review all methods of determining subcatchments on a case-by-case basis. The applicant must provide a reach description and reach routing analysis for each drainage structure and provide pond descriptions and storage routing calculation for any stormwater management structure, detention pond and culvert backwater areas. A natural or man-made waterbody is not considered an impervious area, but is treated as an immediate runoff surface in curve number calculations. Acceptable stormwater methodologies and models include, but are not limited to, "TR-20 - Computer Program for Project Formulation - Hydrology," Second Edition, U.S. Department of Agriculture, Soil Conservation Service (March 1986); and "TR-55 - Urban Hydrology for Small Watersheds," Second Edition, U.S. Department of Agriculture, Soil Conservation Service (June 1986); "WIN TR-55 2003.00.24 Microcomputer Program," (January 12, 2003); and "HEC-HMS Flood Hydrology Package," U.S. Army Corps of Engineers (January 2001). Any methodology or model other than those listed must have prior approval from the Department.
06-096 C.M.R. ch. 500, § 7