Drainage Criteria

A Drainage Report is generally required when land-disturbing activities occur (parking lot expansion, regrading, etc.).

Drainage reports are required for subdivisions (16.28) and solar facilities (17.168).

For subdivisions, as a condition of approval of the final plat, a Final Drainage Report (FDR) will be required. Comments regarding the FDR will need to be addressed prior to acceptance of the Report.

For solar facilities, as a condition of approval of the 1041 permit, a FDR will be required. Comments regarding the FDR will need to be addressed prior to acceptance of the Report.

For other land use applications (e.g. Special Use Permit, Zoning Variance, condition of an Access Permit), a Drainage Report may be required depending on if there will be land-disturbing activities. It will be reviewed as a Final Drainage Report.

All applications shall be submitted in OpenGov.

Preliminary Drainage Reports for preliminary plans (subdivisions) should be submitted through a Preliminary Plan (PREL) application.

Preliminary Drainage Reports for solar facilities should be submitted through a 1041 Permit Areas and Activities of State and Local Interest (SLI) application.

Drainage Reports for other land use applications (e.g. Special Use Permit, Zoning Variance, condition of an Access Permit) will be submitted through a stormwater construction discharge permit (SCDP). If it is determined a stormwater construction permit is not required, the permit fee will be waived but the permit application will serve as a repository for all documentation and review comments.

An abbreviated drainage report is acceptable if it meets the requirements of the April 2023 City of Pueblo Drainage Criteria Manual.

Drainage reports submitted after April 2023 should follow the requirements of the April 2023 City of Pueblo Drainage Criteria Manual.

If the application is regarding a medium-scale or utility-scale solar project, the “Acceptable Methods for Modeling Solar Panels” will apply. Please see “FAQs for Modeling Solar Panels” for more information.

A SWMP is required when the disturbed area is one acre or more. An ESCP is required when the disturbed area is greater than 1,000 square feet and less than 1 acre. These requirements apply within and outside the MS4 boundary.

Yes. It can be submitted in a preliminary state and refined for final. Specifically:

1. A larger scale for the preliminary ESCP/SWMP is acceptable,
2. General SCMs can be shown without supporting calculations, and
3. Identification of general drainage patterns and general SCMs is acceptable (full detail is not necessary).

The limits of construction and limits of disturbance should be shown on the SWMP.

In certain cases, detention for flood control is required. Detention for water quality may also be required. Please refer to the Pueblo City DCM. Detention facilities, if required, should be shown on the drainage plan of the report. Please note that detention ponds (EDBs) are not the only type of detention facilities.

If they are specified on the preliminary plan and if they are used for detention, they will need to include the footprint and volume calculations.

Please include the sediment basin detail (MHFD SC-7 or a comparable reference) and size the basins off the detail. Note: fine grading is not required in the preliminary report.

Upload blank documents if the application does not require an O&M or Facilities Maintenance Agreement.

If a project is within or outside the County MS4 boundary and the disturbed area is one acre or more, then a PC-SCP and CDPS-SCP will be required.

Refer to “Chapter 8.26 Stormwater Quality” of the Pueblo County Code.

Refer to the General Permit and to “Chapter 8.26 Stormwater Quality” of the Pueblo County Code.

Two approaches for modeling paneled areas have been identified. The first approach assumes that paneled areas will change site hydrologic conditions so that runoff increases. The second approach assumes that paneled areas will not increase runoff.

Runoff should be restricted to historic conditions. Paneled areas have the potential to increase runoff and erosion. Issues of concern are: (1) compacted soils, (2) loss of vegetation density and diversity, and (3) panel orientation.

The requirements for these two approaches are described by Methods 1 and 2.

• Method 1: A higher imperviousness that addresses the concerns listed above is required by Method 1. Please note that control measures may be required with this method.
• Method 2: The assumption that paneled areas will not increase runoff needs to be verified to address our concerns. Verification is done by providing the additional surveys and reports required for Method 2.

The preliminary drainage report can be submitted using Method 1, and if desired, the final drainage report could be completed using Method 2.

Applicants who plan to use Method 2 later should submit a pre-construction soils report with the preliminary drainage report.

The applicant should determine what imperviousness is appropriate for the solar panels to address concerns of (1) compacted soils, (2) loss of vegetation density and diversity, and (3) panel orientation. Justification, through documentation and/or supported calculations, will be required.

If this determination is not made by the applicant, then an imperviousness for light industrial areas, as shown in Table 6-3 of the MHFD's USDCM will be used, which is 80% imperviousness.

Both the space between the panels and under the panels. These areas represent the paneled areas.

The location should be determined by the engineer of record with regards to anticipated changes between existing and proposed conditions. The location(s) should be representative of the full site, including capture of varying hydrologic soil groups and vegetation cover.

The number of test points is site dependent. The number of points collected should be such that the engineer of record can attest that they are representative of the full site to be developed and include areas where varying hydrologic soil groups and vegetation cover exist.

It is recommended that the CDOT vegetative survey transect procedure be used. For areas greater than 20 acres of disturbance, a minimum of 2 additional transects shall be collected per 20 acres.

Determination of 100% of existing vegetation regrowth will be based on comparison of the transects. The locations should be provided so that the regrowth can be verified.

Pre-construction transects can be completed at any time that the ground is visible for photo documentation. Post-construction transects can be collected as soon as surface disturbing activities have been completed and vegetation has been established.

The reports to be included are those listed in the major bullets of Method 2 (Existing vegetation survey, initial/final soil reports, vegetation plan, etc.) If these reports are not included, Method 1 should be used.

When the installation of panels creates conditions that will lead to pooling of runoff or creates channelized conditions susceptible to increased erosion potential, BMPs or other control measures should be installed to promote positive sheet flow drainage conditions.

Use of permanent or temporary control measures can be used to minimize erosion while permanent vegetation is established. MHFD and CDOT include examples of control measures that would be acceptable.

When Method 2 is not applicable, Method 1 would need to be used. In most cases, existing imperviousness is less than the imperviousness used for Method 1. Since historic runoff conditions should not be exceeded, control measures would become necessary to reduce runoff to historic conditions. The specific type of control measure used will be determined by the engineer of record.

The final site conditions should be consistent with the drainage report and design plans. If the final site conditions differ from the report and plans, revisions would become necessary.

A lower panel height can be used if it can be demonstrated by the engineer of record that the plant diversity encountered during the pre-construction survey will not be impaired through installation of a lower panel height.