County of Bernalillo

(a) State water law, flood control authorities, and application to post-construction BMP selection and limitations.

1. It is the county’s understanding for the purposes of this article that the office of the state engineer’s position is that all detained stormwater must be infiltrated or released within 96 hours and local flood control authority requirements prevail over the requirements of the MS4 permit.
2. The MS4 permit provides that where state water law limits the ability to fully manage stormwater quality design volume on site, measures to minimize increased discharge consistent with requirements under state water law must still be implemented, and also that local flood control requirements and MS4 permit requirements may be met through a combination of on-site and off-site controls.
3. The MS4 permit contains a list of possible infeasibility considerations for post-construction BMPs including: The lot being too small to allow for infiltration capacity; soil instability; a site use that is inconsistent with capture and reuse; other physical conditions; and compliance with on-site flood-control requirements leaves insufficient area. The permit allows for consideration of “multiple criteria that rule out an adequate combination of the practices” set forth in the permit, and further indicates that state water law may limit the ability to fully manage the stormwater quality design volume on site.
4. Where applicable state water law requires permits that limit the ability to use stormwater BMPs requiring infiltration, reuse, or other beneficial uses, BMPs may be determined by the county to be infeasible and alternative compliance may be considered.

(b) Post-construction BMP design requirements and implementation.

1. For all development and redevelopment projects with land disturbances equal to or greater than one acre, including sites which disturb less than one acre but are part of a larger common plan of development, that discharge into the county’s storm drainage system, post-construction water quality BMPs to manage the stormwater quality design volume are required. This requirement is in addition to any other requirements that may apply. These BMPs shall be subject to the approval of the county engineer and stormwater compliance manager.
2. The selection of management BMPs must be included in a stormwater quality design (incorporated into the grading and drainage plan as part of the preconstruction review process and as such, subject to inspection during construction, at final inspection, and as a condition of final construction approval) that manages the 90 thpercentile stormwater quality design volume for new development and the 80 thpercentile stormwater quality design volume associated with redevelopment sites. The stormwater quality design volume will be managed on-site, as defined in this article, consistent with the MS4 permit intent to reduce pollutants in stormwater. Calculation of the stormwater quality design volume is defined in the Bernalillo County Technical Standards and the Bernalillo County Green Stormwater Infrastructure Low Impact Design Standards. Where an infeasibility determination is made, the stormwater quality volume will be treated to the extent feasible and as approved by the county engineer and stormwater compliance manager.
3. BMPs will be selected and designed to manage flow from the contributing area impervious surfaces. Selected BMPs should include the following elements to improve on-site stormwater runoff quality:

   a. Incorporate stormwater harvesting basins, bioswales, depressed landscaping, and other features to manage stormwater runoff and increase infiltration into the soil media.

   b. Grade impervious surfaces, such as driveways, during construction to drain to vegetated areas.

   c. Minimize the area of impervious surfaces such as paved areas, roofs, and concrete driveways.

   d. Incorporate pervious or porous surfaces where allowable (e.g. permeable pavement or pavers, or other pervious/semi-pervious materials) that minimize runoff.

   e. Direct runoff from impervious surfaces/areas into active water harvesting systems (e.g. rainwater collection systems such as barrels or cisterns) or passive water harvesting areas (e.g. depressed landscape areas, swales, etc.).

4. The BMPs must include an evaluation by the applicant of the GSI/LID practices as provided in the county’s Green Stormwater Infrastructure Low Impact Design Standards, Development Guidelines for Water Conservation, and the Bernalillo County Technical Standards. The evaluation must include selected GSI/LID BMPs that will be implemented.
5. As-built plans for stormwater quality designs must be submitted prior to final inspection. Grading and drainage plans or other required planning documents must specifically identify post-construction BMPs that are required to be maintained and inspected.
6. BMP(s) must be inspected by the stormwater compliance manager or other county-designated qualified person and found to be in compliance with all approved plans and specifications prior to the release of certificate of occupancy or other county-required approval for the site.
7. Post-construction agreements and inspection and maintenance requirements are as outlined in subsections 38-414(c) and 38-414(d).

(c) Alternative compliance for post-construction due to infeasibility.

1. The applicant may submit to the stormwater compliance manager and county engineer, or designees, a request for a determination of infeasibility for on-site management of all or a portion of the stormwater quality design volume based on the limitations provided in subsection 38-412(a)(4) above. If the request is confirmed, an alternative compliance strategy acceptable to the stormwater compliance manager and the county engineer, or designees, shall be implemented to address stormwater quality concerns prior to discharge from the property.
2. The limitations of section 38-412(a)(4) above should not be construed to be exclusive, and other valid basis, other than costs, may be considered. Such basis may include, but is not limited to:

    

3. a. Entitlements granted prior to the effective date of the permit.

   b. Previous authorization from the county or MS4 permittees to utilize existing public off-site infrastructure granted prior to the effective date of the permit.

   c. Proposed use of a public, common, or private facility that is not strictly on-site, but that is designed to be utilized by an area or plan of common development (i.e., minor facilities incorporated into a master plan, planned community, subdivision, or village center).

   d. Proposed and contracted use of a joint private facility, with agreement terms subject to approval by the county engineer, though not an area of common development, and located prior to a discharge to the MS4 (e.g., reciprocal drainage agreements and easements).

   e. Instances where an infeasibility determination has been made and appropriate public or private drainage facilities are available off site, and will be used in a manner consistent with the goals and intent of this division to manage the stormwater quality design volume to mimic predevelopment hydrology and to address stormwater quality improvement, and located prior to discharge to waters of the US, and as determined and approved by the county engineer, stormwater compliance manager, and by the receiving facility owner.

4. Availability of off-site private facilities will be demonstrated through appropriate engineering reports demonstrating the shared capacity of the facility and a joint voluntary agreement between parties that addresses ownership, maintenance, and inspection responsibilities that is equally, jointly, and severably enforceable against and between all parties.
5. Availability of off-site public facilities of the county or other MS4 permittees as documented by and subject to:

a. A determination by the county, a letter from the applicable MS4 permittee, as pertains to their respective facilities conditioned as needed, indicating that:

1. 1. 1. 1. Existing infrastructure capacity is adequate to accept the stormwater quality design volume from the fully developed watershed or sub-watershed within which the development or redevelopment is located.
         2. The requirement for on-site retention from the releasing property may, accordingly, be waived for all or a portion of the stormwater quality design volume, and clearly stating the proportional volume that must be addressed on-site.
         3. Specifying any water quality treatment that is required prior to release.
         4. Assurance to the county that stormwater quality treatment requirements will be fully addressed by the accepting parties’ infrastructure prior to discharge to an MS4 and/or waters of the US.

b. Full or partial on-site treatment for stormwater quality treatment acceptable to the county engineer and to owner and operator of the alternate compliance facility will be required prior to discharge to the receiving facility. The more stringent treatment requirement specified by the county engineer, stormwater compliance manager, and the MS4 permittee will apply.

c. No discharge of any portion of the stormwater quality design volume (other than under those approved through other NPDES or MS4 permits) will be discharged from the site to any MS4 without a minimum level of treatment (GSI/LID or structural) to address floatables, gross pollutants, and/or site-specific pollutants of concern as determined by the county engineer and the stormwater compliance manager.

d. The maintenance of the on-site stormwater quality feature remains the responsibility of the property owner/operator, subject to the provisions of sections 38-415 through 38-417 and related enforcement provisions.

e. Annual inspection of the installed on-site water quality feature will be performed and documented by the owner/operator and records will be provided upon request by the county engineer and/or equivalent position of the MS4 permittee. Because of the reliance on off-site public facilities, an annual inspection applies rather than the three-year inspection schedule for private facilities specified for post-construction inspection and maintenance, as described in subsection 38-414(d)(2) of this article.

(d) Post-construction inspection and maintenance.

1. Private stormwater facilities shall be maintained by the facility or property owner to standards established by the county engineer, published in the Bernalillo County Green Stormwater Infrastructure Low Impact Development Standards and the Bernalillo County Technical Standards, and/or in related county rules.
2. Periodic inspection and certification of private facilities by a state professional engineer or otherwise qualified stormwater person (as determined by the county engineer, stormwater compliance manager, or designees) are required of the facility/property owner and shall occur no less frequently than once every three years from the date of final construction inspection.

   1. For facilities that have been approved for off-site treatment of the stormwater quality design volume due to infeasibility, as described in subsection 38-412(c), due to reliance on off-site public facilities, an annual inspection applies rather than the three-year inspection schedule for private facilities specified for post-construction inspection and maintenance.

   2. The responsibility and cost for the inspection is the responsibility of the private facility owner and/or property owner. The facility owner and/or property owner of each structural BMP shall keep records of inspections, maintenance, and repairs for at least five years from the date of creation of the record, whether the inspection schedule is annual or every three years.

3.  

   Documentation of the inspection, maintenance activities, and repairs shall be provided to the county engineer and stormwater compliance manager, or designees, upon request and shall be maintained electronically as part of the county’s permit tracking system. Copies of the inspection reports shall be kept on file at the subject property/facility or at the offices of the property owner and/or manager, and shall be made available within two working days of an inspection request (whether verbal or written). A facility or BMP that cannot be certified or for which records cannot be provided in a timely manner shall be certified by current inspection at cost to the owner. Deficiencies noted in the inspection will be corrected within 60 days of notice from the county that such correction or inspection is needed unless a more immediate action is deemed necessary by the county engineer and stormwater compliance manager.
4. All on-site post-construction BMPs or alternate compliance methods and techniques are subject to random inspections by the county engineer per the inspection provisions of section 38-409.
5. Inspections and inspection programs by the county may be conducted or established on any reasonable basis, including but not limited to routine inspections; random inspections; inspections based upon complaints or other notice of possible violations; and joint inspections with other agencies inspecting under environmental or safety laws. Inspections may include, but are not limited to: Reviewing maintenance and repair records; sampling discharges of surface water, groundwater, and material or water in BMPs; and evaluating the condition of BMPs.
6. Enforcement provisions will apply per section 38-402 of this article.