HomeMy WebLinkAboutAgreement_850 Moore Dr_0061.2023.BRESRECEPTION#: 705121, R: $58.00, D: $0.00
DOC CODE: AGREEMENT
Pg 1 of 10, 09/30/2024 at 03:36:13 PM
Ingrid K. Grueter, Pitkin County, CO
STORMWATER BEST MANAGEMENT PRACTICES OPERATIONS
AND MAINTENANCE AGREEMENT
Permit Number: Engineering Approval Date (for official use):
THIS AGREEMENT, made and entered into this �2S day of nJ��+ , 20 ZL , by and between
(Insert Full Name of Owner) an e s „ wr% hereinafter called the
"Landowner", and the City of Aspen, Colorado, hereinafter called the "City".
WITNESSETH
WHEREAS, the Landowner is the owner of the following described properties located in the City of Aspen,
Pitkin County, Colorado
Salesforce Master Permit Number: D O (o I - 9D A 3 - B R-CS
Parcel Identification Number: cif 351411I
Legal Description (Subdivision, Block, Lot):
Street Address: 950 moo r"2. !Dr•i y
Common Name: 850 MooYe- Driv -.
WHEREAS, the Landowner is proceeding to build on and develop the property; and
WHEREAS, the stormwater management BMP Operations and Maintenance Plan for the property identified
herein has been approved by the City, herein after called the "Plan", which is attached hereto as Appendix A
and made part hereof, as approved by the City, provides for management of stormwater within the confines of
the Property through the use of stormwater management or Best Management Practices (BMPs) facilities;
and
WHEREAS, the City and the Landowner, its successors and assigns, agree that the health, safety, and
welfare of the residents of City of Aspen, Colorado and the maintenance of water quality require that on -site
stormwater management/BMP facilities be constructed and maintained on the Property; and
WHEREAS, the City requires, through implementation of the Plan from the Landowners dated and
attached hereto, that on -site stormwater management/BMPs as shown on the Plan
be
adequately constructed, operated, and maintained by the Landowner, its successors and assigns.
NOW, THEREFORE, in consideration of the foregoing premises, the mutual covenants contained
herein, and the following terms and conditions, the parties hereto agree as follows:
v. 2023
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RECEPTION#: 705121, 09/30/2024 at 03:36:13 PM, Pgs 2 of 10, Ingrid K. Grueter, Pitkin County, CO
IN WITNESS WHEREOF, the undersigned have hereunto affixed their signatures as of the date first above
written.
(La&owner signature must be notarized)
THE FOLLOWING SECTION MUST BE COMPLETED BYA NOTARY PUBLIC.
STATE OF GeLGRABO —) N
Lam.) ss. o N
County of P+04A )
Y =T
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The foregoing instrument was acknowledged before me this a5 Day of - 20 Wale W
By (Print Landowner Name) Na ra l C • C=J OW w� Q
QZ' -LU
UH�Uc
EZ
FITNESS W HAND AND OFFICIAL SEAL. O=Va E
Notary commission expires: ILAo
(Date) (Notary Public) Z >
(Address)
WN-161"AN,
THE FOLLOWING SECTION MUST BE COMPLETED BYA NOTARY PUBLIC.
STATE OF COLORADO )
) ss.
County of Pitkin )
The foregoing instrument was acknowledged before me this
DATE: 9 !so 12-L�
30 Day of SgZSjLbe.r 20Z� , by PJ MU. YKIA
(Print Name)
WITNESS W HAND AND OFFICIAL SEAL.
Notary commission expires: J 0 t4 12 , 202lo
(Date) (Notaryblic)
42-7 Rio GrO note. PL ASpe n C-D B t (01 I
LORENA VARGAS
NOTARY PUBLIC
STATE OF COLORADO
Notary ID 20174029180
My Commission Expires July 12, 2026
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RECEPTION#: 705121, 09/30/2024 at 03:36:13 PM, Pgs 3 of 10, Ingrid K. Grueter, Pitkin County, CO
1. Construction of BMP facility by Landowner. The on -site stormwater management/BMP facilities shall be
constructed by the Landowner, its successors and assigns, in accordance with the plans and specifications
approved by the City and identified in the Plan.
2. Duty of Operation and Maintenance of Facility. The Landowner, its successors and assigns, including
any homeowners association, shall adequately operate, inspect, and maintain the stormwater
management/BMP facilities as acceptable to the City and in accordance with the specific operation,
inspection, and maintenance requirements noted in the Plan. Adequate operation and maintenance is
herein defined as good working condition so that these facilities are performing their design functions.
3. Duty of Documentation. The Landowner, its successors and assigns, shall document inspections,
maintenance, and repairs performed and provide said documentation to the City or its representatives upon
request.
4. Right of Entry on Property. The Landowner, its successors and assigns, hereby grant permission to the
City, its authorized agents and employees, to enter upon the Property at reasonable times and upon
presentation of proper identification, and to inspect the stormwater management/BMP facilities whenever -
the City deems necessary. The purpose of inspection is to follow-up on suspected or reported deficiencies,
to respond to citizen complaints, and/or to assure safe and proper functioning of the facilities. The City shall
provide the Landowner, its successors and assigns, copies of the inspection findings and a directive with
timeline to commence with the repairs if necessary.
5. Failure to Maintain. In the event the Landowner, its successors and assigns, fails to construct, operate
and maintain the stormwater management/BMP facilities in good working condition acceptable to the City,
the City, its authorized agents and employees, may enter upon the Property and take whatever action(s)
deemed necessary to correct deficiencies identified in the inspection report and to charge the costs of such
construction or repairs to the Landowner. It is expressly understood and agreed that the City is under no
obligation to install, construct, or routinely maintain or repair said stormwater management/BMP facilities,
and in no event shall this Agreement be construed to impose any such obligation on the City.
6. Reimbursement by Landowner. In the event the City pursuant to this Agreement, performs work of any
nature, or expends any funds in performance of said work for labor, use of equipment, supplies, materials,
and the like, the Landowner, its successors or assigns, shall reimburse the City upon demand, within thirty
(30) days of receipt thereof for all actual costs incurred by the City hereunder.
7. Duty to Inspect by City. The City, its employees or representatives, may inspect the stormwater
management/BMP facilities at a minimum of once every three years to ensure their continued and adequate
functioning.
8. Release of City. The Landowner, its executors, administrators, assigns, and other successors in interests,
shall release the City, its employees and designated representatives from all damages, accidents,
casualties, occurrences, or claims which might arise or be asserted against said City, employees, and
representatives from the construction, presence, existence, operative or maintenance of the stormwater
management/BMP facilities by the Landowner or City. In the event that a claim is asserted against the
City, its elected officials, City Officers or employees, the City shall promptly notify the Landowner and the
Landowner shall defend, at its own expense, any suit based on the claim. If any judgment or claims
against the City's employees or designated representatives shall be allowed, the Landowner shall pay all
costs and expenses regarding said judgment or claim.
9. Recording of Agreement running with the Property. This Agreement shall be recorded in the real
property records of Pitkin County, Colorado, and shall constitute a covenant running with the Property or
land, and shall be binding on the Landowner, its administrators, executors, assigns, heirs and any other
successors in interests, in perpetuity.
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DRAINAGE REPORT FOR
850 MOORE DRIVE
ASPEN, CO 81611
I hereby affirm that this report and the accompanying drawings for the analysis of 850 Moore
Drive, Aspen, Colorado was prepared under my direct supervision for the owners thereof in
accordance with the provisions of the City of Aspen Urban Runoff Management Plan with
proposed variances and exceptions listed thereto. I understand that it is the policy of the
City of Aspen that the City of Aspen does not and will not assume liability for drainage
facilities designed by others.
Permit #: 0061-2023-BRES
October 27, 2022
UPDATE FOR DRYWELL MODIFICATION: SEPTEMBER 2023
Rick Barth, P.E. 36749
Prepared by
GSGM
118 West Sixth Street, Suite 200
Glenwood Springs, CO 816o1
970.945.1004
970.945.5948 fax
RECEPTION#: 705121, 09/30/2024 at 03:36:13 PM, Pgs 5 of 10, Ingrid K. Grueter, Pitkin County, CO
850 Moore Drive, Aspen, Colorado October 27, 2022
DRAINAGE REPORT FOR
850 MOORE DRIVE
ASPEN, CO 81611
REVIEWED BY
RICK BARTH
SGM Project # 2020-555.002
I:\2020\2020-555-850MooreDr\002-Civil\E-Reports\SGM\Drainage Report\Workina Files\850
Moore - Drainage Report.docx
6 Drainage Report for Major Design 1
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850 Moore Drive, Aspen, Colorado October 27, 2022
TABLE OF CONTENTS
1.0
Existing Site 3
1.1
Description of Existing Site 3
1.2
Description of Existing Drainage 3
2.0
Proposed Project 3
3.0
Proposed Basins 4
3.1
Basin 1 4
4.0
Peak Flow Methodology 4
5.0
Water Quality Methodology 5
6.0
Maintenance 6
6.1
Rain Garden 6
7.0
Conclusion 6
LIST OF APPENDICES
Appendix A — Proposed Drainage Schematic & WQCV Credits
Appendix B — Water Quality Capture Volume Calculations
Appendix C — Peak Flow Calculations — Proposed Conditions
Appendix D — Soil Study
Drainage Report for Major Design ii
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850 Moore Drive, Aspen, Colorado October 27, 2022
1.0 Existing Site
1.1 Description of Existing Site
The physical address of the project is 850 Moore Drive, Aspen, Colorado, and is located on
parcel no. 2735-141-11-109. This parcel is approximately 2.233 acres and is owned by
Nancy Crown. The existing structure on the parcel is a single-family residence with an
attached garage. The project focuses on expanding the patio to include a pool and spa on
the northeast comer of the house.
1.2 Description of Existing Drainage
Existing storm water runs off the existing house as sheet flow. Topography of the site
suggests that the existing drainage patterns flow from the south side of the property to the
north side of the property. Offsite runoff is not known to affect this property, specifically in
the area that this work is going on.
A web soil survey was performed and found the soils to be Callings-Yeljack complex,
classified as Hydrologic Soil Group C will well -draining soils consisting of gravelly loam to
very cobbly sandy clay loam.
UPDATE SEPTEMBER 2023
Upon site investigation and additional historical records, it was discovered that a previous
drywell, circa 2003, was installed in the area of the pool/patio modification and would need
to be relocated or otherwise replaced. With this investigation it was discovered this was a
rather large manhole with significant surrounding gravels. Understandably the client and
contractor desired to not impact the site more than is necessary. Review of the previous
HCE report showed a significant oversizing of this (and the other) drywells on site due to an
exceedingly conservative approach.
In our investigation we looked at solely the Rational Method calculation for 100-year storm
volumes to "resize" the required volume needed and our results were comparable to the
HCE report for that methodology. In this analysis we are able to affirm a slightly smaller
drywell with significantly less surrounding gravels, essentially just enough to install the
manhole (as opposed to the 6+ feet of additional gravel radius).
Likewise, we affirmed the other basins as well just for coherence on the entire site. This
report is to present our findings, associated adjustment and justification for our drainage
plan alteration.
2.0 Proposed Project
The primary purpose of this project is to remodel and expand for the addition of an exterior
pool and spa in an area already connected to the existing home. The proposed project is
considered a major project as defined by the COA Urban Runoff Management Plan (URMP)
because more than 1000 square feet and less than 25% of the site will be disturbed.
Storm water quality treatment consists of tree canopies and a rain garden with an overflow
weir. The tree canopies exist adjacent the patio that is being proposed. The rain garden will
6 Drainage Report for Major Design Appendix -
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850 Moore Drive, Aspen, Colorado October 27, 2022
be located northwest of the proposed patio and north of the existing residence. The rain
garden will be set down the hill a bit to avoid disturbing existing trees.
UPDATE SEPTEMBER 2023
With the discovery of the drywell noted above, and the need to relocate a drywell anyway, it
was the applicant's desire to combine our drainage needs calculated above with the
relocated drywell, again, to minimize site disturbance. The original exercise and submission
placed a rain garden downhill from the target construction area. This will not need to be
done as this calculated volume is incorporated into the relocated drywell analysis.
3.0 Proposed Basins
The proposed site is modeled as 1 basin as defined by the proposed landscaping project
and can be seen in Appendix A. Summary of the basins and detailed calculations can be
found in Appendix B. Storm water runoff will be routed to the rain garden for water quality
treatment and detention through a combination of grading, drain inlets and drain lines. All
proposed storm water runoff will discharge from the site as sheet flow in a northerly direction
to match historical flow patterns or be infiltrated within the rain garden. The basin is detailed
in the sections that follow, with descriptions on how the required WQCV is treated by BMPs
within the basin. WQCV is calculated based on tree canopy credits, proposed water quality
drywell, and green space areas.
3.1 Basin 1
Basin 1 is located on the east side of the site and northeast of the existing residence. This
basin is 1167 square feet of which 1167 square feet is impervious. Improvements in this
area are grading and landscaping and the addition of a pool and spa. Drainage will be
directed ultimately north. Area drains and a trench drain are to collect any runoff from this
proposed project and routed to the rain garden. Water quality for the added impervious area
is being treated by the rain garden and tree canopy credits. See Appendix A for the
proposed location of BMPs in this basin. This area is mostly the eastern portion of the site
that doesn't include the building or existing patio.
UPDATE'SEPTEMBER 2023
This basin equates to the previous HCE report "Basin B".
The other basins were also calculated, although no changes are planned for those locations
or drainage elements.
4.0 Peak Flow Methodology
rJ" Drainage Report for Major Design Appendix
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850 Moore Drive, Aspen, Colorado October 27, 2022
*Clpolletti (Trapezoidal) Weir
Historic 100 year
- Horizontal
Headwater Rain
Flow Rate (Q)
Weir Length
Depth Garden
Q- Basin 1
Lw
Hw Q- Weir
cfs _
ft
h cfs
0.06
0.25
_ _
0.125 0.040
Basin Basin Flow Rate
See App A ____, (cfs)
1 0.11
Basin Design Flow 'Req. Pipe 0 Prop. Pipe Full Pipe Area Full Pipe Flow Depth Pipe
Use Qdes/Qfull d/D
See App A ___ (cfs)_ Inche�-(inches (feefI (cfs) of Flow Capaat
1 0.11 2.792 4 Yes 0.087 0.294 0.381 0.85 0.42 Yes
UPDATE SEPTEMBER 2023 — SEE NEW SPREADSHEET OUTPUT
See the new spreadsheet of basin calculations to 100-year storm volumes. ' In comparison,
the HCE calculation had nearly 4,000 cubic feet of detention volume for the entire site. We
tally around 625 CF, which seems much more in line with current development in the Aspen
area with this level of site impact.
Regardless of the excess, we need to account for the Basin B volume in a new drywell. As
opposed to the 5-foot diameter, 12-foot deep drywell with 6+ feet of gravel around the
perimeter (making a minimum nearly 20 foot diameter hole, we can go with a 5-foot
diameter, 10 foot deep drywell with minimal gravels, hopefully keeping the excavation hole
to 12 feet diameter or less and still avoiding the excavation further down hill.
5.0 Water Quality Methodology
The Required WQCV (ct) for each basin on the property was estimated from Figure 8.13 of
the URMP based on the basin imperviousness and basin area. Then WQCV credits and
treatment were estimated based on the proposed rain garden and the preserved tree
canopy (see further discussion of tree canopy credit below). All water quality treatment is
based on the instruction of section 8.4.1 in the URMP
The Tree Canopy Credit was calculated following the recommendations in section 8.4.1 of
the URMP. Detailed calculations for the Tree Canopy Credit can be found in Appendix B. In
addition, a map showing the designated trees and their canopy areas is shown in Appendix
B. Runoff from all impervious areas will be treated by directing the runoff to grass buffers
and a water quality drywell. All proposed runoff will either infiltrate into the ground or leave
the property as sheet flow and will flow over grass lawn located in the right of way.
6 Drainage Report for Major Design Appendix
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850 Moore Drive, Aspen, Colorado October 27, 2022
6.0 Maintenance
6.1 Rain Garden
Annual inspection of the rain gardens should be taken to ensure that the material is not
clogged and inhibiting drainage. Inspection after large storms should also be taken to
ensure that the rain garden is draining as it should, and overflow routes and inlets are not
clogged or iced over. Replacement and/or cleaning of the material should be performed
when it is observed that the rain garden is performing less than optimally in its existing
condition. Cleaning of the underdrain should be inspected annually and after large storms
that could cause debris to clog the pipes. Cleanouts have been provided to facilitate this
maintenance.
UPDATE SEPTEMBER 2023 — ADDED MAINTENANCE LANGUAGE
6.2 Dry well
Dry wells must be inspected and maintained yearly to remove sediment and debris that is
washed into them. A maintenance plan shall be submitted to the City in the Drainage Report
describing the maintenance schedule that will be undertaken by the owners of the new
residence or building. Minimum inspection and maintenance requirements include the
following:
• Inspect dry wells as annually and after every storm exceeding 0.5 inches.
• Dispose of sediment, debris/trash, and any other waste material removed from a dry well
at suitable disposal sites and in compliance with local, state, and federal waste regulations.
• Routinely evaluate the drain -down time of the dry well to ensure the maximum time of 24
hours are not being exceeded. If drain -down times are exceeding the maximum, drain the
dry well via pumping and clean out the percolation area (the percolation barrel may be
jetted to remove sediment accumulated in perforations). Consider drilling additional
perforations in the barrel. If slow drainage persists, the system may need to be replaced.
7.0 Conclusion
...
J_
UPDATE SEPTEMBER 2023
The reconfigured/relocated drywell, sized appropriately for Basin B (our Basin 2) still more
than suffices for stormwater controls to 100-year detention requirements. The remaining
basins and drywells, unaltered by this application, provide in excess of that detention
requirement by a significant amount. We submit this still adheres to CoA URMP standards
in modifying an existing site with appropriate methods, keeping the maintenance in the
"normal" and consistent realm of attention typically provided and no negative downstream
impact.
6 Drainage Report for Major Design Appendix