HomeMy WebLinkAboutFile Documents.219 N Monarch St.0207.2019.ARBK
1517 Blake Avenue, Suite 101
Glenwood Springs, CO 81601
Telephone ~ 970.945.8676
Fax ~ 970.945.2555
www.hceng.com
An Employee-Owned Company
October 10, 2017
Hailey Guglielmo
Development Engineer
(970) 429-2751
hailey.guglielmo@cityofaspen.com
Re: 219 N. Monarch
HCE Project No. 2171613.03
Dear Hailey,
Per our meeting on site on October 9th we are requesting a change to the project to address the
issue regarding the bio-retention pond that we discussed on site. In this case the bio-retention
pond at the south side of the property near the alley is not draining adequately and has been
holding water for several days. See photo of pond from 10-9-19 below.
Current Bio-Pond Excavated to filter fabric elevation.
Civil engineering
Land Surveying Civil Engineering
10/16/2019
Reviewed by Engineering
10/28/2019 10:41:45 AM
"It should be known that this review shall not
relieve the applicant of their responsibility to
comply with the requirements of the City of
Aspen. The review and approval by the City is
offered only to assist the applicant's
understanding of the applicable Engineering
requirements." The issuance of a permit based
on construction documents and other data shall
not prevent the City of Aspen from requiring the
correction of errors in the construction
documents and other data.
We believe this area was compromised during the construction and we are proposing that the
bio-pond for this location be replaced with a drywell that should be able get below the material
that is not percolating. Per the geotechnical report and review of Steve Pawlak with Kumar and
Associates, it is believed that we should be able to get back into the sand, gravel cobble that is
will provide the expected pervious results that were anticipated.
The proposed excavation will be inspected by the Kumar and associates prior to placing the
drywell to verify the materials are acceptable. We have shown the revision on the attached plans
and calculation revisions. Effectively the only thing that is being changed is the increase in
detention due to the use of a drywell. We have added a drain inlet at the low point that will flow
into the drywell and we have attached the inlet capacity for the grate. If the drywell is inundated
the area will backup and flow down the vegetated swale to the 2nd bio-retention pond just like the
current approved design. The WQCV did not change and is 9.8 CF. The drywell increased by
50% due to the requirements for use of a drywell. This volume was found to be 14.7CF. A 4’
diameter manhole with 1’ of gravel and 10’ deep will provide the necessary volumes. These
revisions are reflected on the attached revised Proposed Drainage Basin Map along with some
updated elevations to reflect the surrounding as-constructed plan.
If you have any questions, please feel free to give me a call.
Sincerely,
HIGH COUNTRY ENGINEERING, INC.
Roger Neal, P.E.
Principal
10/16/2019