HomeMy WebLinkAbout20113089.tiff abl 2011 MEMORANDUM
uepartment
TO: Kim Ogle, Planning Services DATE: Novembc144EizOi OFFICE
FROM: Clay Kimmi, P.E., CFM, Public Works Department
WELD 0 NTY
SUBJECT: USR-1792, DCP Midstream, LP, Boulter Site aka LaSalle Gas Plant Final
Drainage Report
The Weld County Public Works Department reviewed the Final Drainage Report that was submitted by the applicant's
engineer on October 31, 2011. Comments made during this stage of the review process will not be all inclusive; as
revised materials are submitted other concerns or issues may arise. All issues of concern and critical issues during
further review must be resolved with the Public Works Department.
COMMENTS:
STORMWATER DRAINAGE:
The applicant's engineer, Enercon has supplied a revised drainage report dated October 19, 2011. The Final Drainage
Report was submitted to Weld County for review on October 31, 2011. This report has been signed and stamped by a
professional engineer. Please address the following comments:
1. The Drainage Report narrative and Note 10 on Attachment C indicate that a truck washing facility will drain
directly into the detention pond and that the detention pond will be equipped with a valve to control releases. The
purpose of the detention pond is to automatically release stormwater runoff from the site in a controlled manner.
The valve on the outfall prevents the automatic release of stormwater and negates the purpose of the detention
pond. Please remove the valve from the construction drawings and the revise Drainage Report.
2. All runoff from the truck wash facility is regulated by the Weld County Department of Public Health and
Environment and cannot be released directly into the detention pond. See Development Standard 11 of the USR-
1792 Resolution for more information. Please remove the references to the truck wash runoff being stored in the
detention pond from the Drainage Report and remove Note 10 from Attachment C.
3. Please add a note to the Section on Centerline portion of the Spillway Detail stating that a filter bed and geotextile
is to be placed under the Riprap.
4. Please add a detail for the 2'x2' Neenah grate to Attachment F. Please add a note to the Concrete Spillway
referring the contractor to the appropriate construction detail on Attachment E. Please add a note to the riprap
stating that a filter bed and geotextile must be installed under the riprap. Please provide the appropriate
specifications for the filter bedding material and the geotextile to be installed.
5. Please provide a legend on Attachment G for all symbology used. Please add a seed mix to the sheet.
6. Please note, per the drainage criteria, riprap smaller than D50 of 12 inches must be mixed with 35% topsoil (by
volume) and must be buried with 4 to 6 inches of topsoil. Please add a note to the appropriate attachments
stating the above requirement if riprap smaller than 12 inches is to be utilized. Alternatively, the riprap sizing can
be revised to show a D50 of 12 inches.
Once the appropriate changes have been made to the Final Drainage Report, please resubmit 2 stamped, signed, and
dated hardcopies of the report. Please submit three full sets (1-24"x36" and 2-11"x17") of the construction drawings that
have been stamped, signed, and dated by a registered professional engineer licensed in the State of Colorado.
GRADING PERMIT:
As the applicant is proposing to disturb more than 1 acre of land, a grading permit is required in order for Weld County to
maintain compliance with Colorado Department of Health and Environment regulations. Please note that a grading permit
cannot be released until the drainage report has been finalized and accepted by Weld County Public Works and the
applicant has signed the improvements agreement and posted the necessary collateral.
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