HomeMy WebLinkAboutFox Crossing Lot 4 - HCE Letter - 8-14-18
300 SO SPRING ST | 202 | ASPEN, CO 81611
970.925.2855 | BENDONADAMS.COM
August 14, 2018
Mr. Kevin Rayes
Planner
City of Aspen
130 So. Galena St.
Aspen, Colorado 81611
RE: Fox Crossing Lot #4 – Pre-Development Topography
Mr. Rayes:
Please accept this supplement to our application regarding the predevelopment topography of
Fox Crossing Lot #4. The City of Aspen Engineering Department requested additional background
information from our civil engineer, High Country Engineering. Attached, please find a Letter from
HCE along with supporting maps and analysis.
Please let us know if additional information is needed or if we can assist with a site visit or
correspondence between City Engineering and High Country Engineering.
Kind Regards,
Chris Bendon, AICP
BendonAdams LLC
Attachments:
1. Letter from HCE with attachments
H ISTORIC TOPOGRAPHY CE RTIFICATION LETTER
To whom i t may concern,
Please accept this report in response to your request to examine the pre-development
topography of Lot #4 within the Fox Crossing Subdivision located in Aspen, Colorado.
Your request relates to the City of Aspen seeking an understanding of the "natural"
grade of the site prior to development activity to be used as the basis for devel opment
measurements. I have performed an analysis of the site and offer the following
findings:
The site and i ts surrounding context show i ndirect effects of mining activity. A railroad
spur accessing the Smuggler Mine, various waste rock and mining spoil dump sites,
roadways, and development activities all potentially affected grades. Many of these
activities have no or very limited documentation.
High Country Engineering has prepared the attached analysis entitled "Historic
Topography, Lot 4, Fox Crossing". This analysis is an aggregation of two reliable and
competent sources. The 1 958 Aspen, Colorado, and Vicinity Topographic Map
prepared by Falcon Air Maps of Denver, Colorado, attached. The 1 958 Falcon Air map is
widely considered by local professionals to be the most reliable documented source of
Aspen area topography prior to modem-day construction activities. This map pre-
dates significant development, especially of lands outside of the Original Aspen
Townsite. An additional source was considered: that being an improvement and
topographic plat provided by PLS 33645 for Lot 5, Fox Crossing, attached. This survey
was performed utilizing the NAVD 88 source derived from the City Of Aspen
Coordinate system as modified from the Colorado State Plane, Central Zone. In
connecting and analyzing the common contour lines between the Falcon Air Maps
(NGVD 29 datum) and the COA system a standard conversion factor (National
Geodetic Vertical Datum Transformation) for NGVD 29 to NAVD 88 was used for the
geomatic translation.
These sources provide professional corroboration and the ability to "tie" topographic
information to the 1 958 Falcon Air map and to actual site conditions.
A potential third source would be an examination of soil boring data. Site borings
could confirm a significant depth of overburden but without any subsurface organic
layer. There is a possibility that past grading activity did not just merely fill-in the site,
but, that previous activity exported substantial material from the site and more-recent
activity returned material back to the site.
In my professional assessment, the attached analysis provides a competent, rational
assessment of "natural site conditions prior to development." The assessment is
substantiated with relevant and reliable information available to professional land
surveyors and avoids any and all unsubstantiated speculation concerning prior activities
that may have affected grade. The assessment pre-dates development of the Hunter
Creek Condominiums to the north and the Centennial Condominiums to the east which
l ikely involved mass grading activities. The assessment utilizes the oldest known
topographic land survey information available.
I also offer that use of the HCE pre-development grade analysis results in a base-line
property grade in context with neighboring properties. Use of this assessment will not
result in a development aberration, a development dramatically out of synch with i ts
surrounding context. I assume this is an important consideration to the City of Aspen
and to surrounding property owners.
High County Engineering is a full-service Civil Engineering and Land Surveying company
with close to 30 years of experience focused on l and surveying, civil engineering, and
l and development i n the Aspen Area. I am a licensed Professional Land Surveyor
(Colorado PLS # 23875) and to the best of my knowledge, information and belief state
that this report is a valid assessment of the "pre- development" condition of Fox
Crossing Subdivision Lot #4.
Exhibit 1
1958 Falcon Air Map
9/28/15
Lot 5 Survey
9/28/15
Lot 4 Proposed Pre-
Development Topography