HomeMy WebLinkAboutLetter Acknowledging City Standards Phillips Engineering
Providing Civil Engineering Services to College Station and Surrounding Communities
4490 Castlegate Drive, College Station, Texas 77845 (979) 690 -3141
April 19, 2011
Josh Norton
Development Services
City of College Station
P.O. Box 9960
College Station, Texas 77842
RE: LETTER ACKNOWLEDGING CITY STANDARDS
CASTLEGATE II SUBDIVISION, SECTION 200
COLLEGE STATION, TEXAS
Dear Josh:
The purpose of this letter is to acknowledge any deviations from the B /CS Design Guideline Manual during the
design of Castlegate II Subdivision, Section 200. The following deviations are hereby noted:
1. Both the existing and the new detention ponds were not specifically designed to capture and detain the
2, 10, 25, and 50 year storm events. This was in accordance with an agreement with City staff
following conversations with the engineer developing the Spring Creek LOMR. However, when runoff
from these storm events were computed using the same HEC -HMS model as the 100 yr event, all peak
runoff rates fell below the pre - development flowrates. Even though this was not the original intent, a
reduction in the peak runoff rates was an unexpected benefit.
2. The low point in the berm surrounding the existing pond in Castlegate does not meet the required
freeboard above the blocked outlet conditions WSEL. This is explained in the Response to Comments.
The freeboard is computed at 0.2 feet instead of 0.5 feet as called for in the Design Guidelines.
3. WS Phillips Parkway is being constructed as a half - street as requested by the City staff. Full width is
only provided at the intersection of Victoria Avenue.
4. Sidewalks along WS Phillips Parkway will be constructed in a Common Area that is more than 3 feet
from the back of curb as called for in the Design Guidelines.
5. The 10' bike path along WS Phillips Parkway is being constructed outside of the pavement instead of a
separate lane inside the paved area as called for in the Design Guidelines.
6. The reinforced concrete box culverts under WS Phillips Parkway are specified to meet ASTM C -1433.
This is the new standard that replaces ASTM C -789 and C -850 that are called for in the Design
Guidelines. The plans also allow an option to build cast -in -place box culverts in accordance with
TxDOT MC -6 -16 Standard.
7. A segment of the sewer line on Hadleigh Lane exceeds 14 feet in depth. The Design Guidelines call for
a 30 ft wide easement where this occurs. Our design calls for the line to be constructed in a 20 foot
easement, but the available ROW behind the curb provides an additional 11 feet which yields a total of
31 feet available to maintenance crews to work on this line.
I also acknowledge that, to the best of my knowledge, the details provided in the construction plans are in
accordance with the B /CS Standard Details.
Sincerely,
/ , 2 11,L_
Kent Laza, P.E., Manag