SS9301-CS 910930 MEMO
TO: M. Shohre Daneshmand, Acting City Engineer ~
FROM: Gary C. Hendricks, Engineering Consultant ~'
SUBJECT: Grapevine Creek Trunk Main, Branch 1 & II
Plan Review
DATE: September 30, 1991
GENERAL COMMENTS
1. On cover sheets provide:
a. Overall city-wide location map highlighting project location,
City Hall and major street.
b. Show names of City officials - City Council - Director of Public Works
- City Manager - City Engineer
2. Specifications, contract documents, and bid documents should be
reviewed by engineering prior to advertising this project.
3. Plans call for 30" & 24" PVC pipe by Carlon. Is this pipe approved
for use in these large diameters? I understand a test section is
being reviewed, but has not been approved. Why not allow other pipe
products. Allowing other pipe products will generally encourage more
competitive prices, suggest:
Thickwall RCP with Limestone aggregate T-Lock Rep
Hobas
Extra strength VCP
T-Lock RCP
The different pipe products would each require specifically designed
embedments, again helping produce more competitive prices.
4. Load pipe deflection calculations should be provided for the soil
conditions and depths anticipated on this project. Are we sure the
Class 4 embedment is adequate in depths of 30 ft. in heavy clay soils?
5. The type of embedment to be used should be indicated in the profile
for reference by the inspector.
6. All manhole rim elevation, which are below the 100-year water
surface, are to be type "S" sealed manholes. The plans should
clearly indicate 100 year water surface and the type and diameter of
manhole to be constructed.
Memo to M. Shohre Daneshmand
September 30, 1991
Page 2 of 3
7. If there are more than 3 type "S" sealed manholes consecutively, than
alternate means of venting shall be provided. (Texas Department of
Health Regulations)
8. What is the contractors access to the Branch I project? Lots are
fully developed along both banks of Grapevine Creek. How is
materials, equipment and spoil moved on and off the project?
9. What are the provisions for Storm Drainage during Branch I
construction? What are the provisions for normal flows during this
project?
10. The existing 12" sanitary sewer is to remain in service during
construction of this project. Close attention to trench safety
details is required to assure protection of the existing line.
11. Since the 12" line must be protected during construction, why not
leave it in service after the project is complete. It could serve as
a factor of safety against surcharge conditions.
12. Where the 30" sanitary sewer is located 3.5 feet inside the 20-foot
easement, the base of all 5-foot diameter manholes will be 8 inches
outside the easement.
13. Where the 30" sanitary sewer is located 2.0 foot inside the 20-foot
easement, the base of all 5-foot diameter manholes will be 2' - 2"
outside the easement.
14. Where the sanitary sewer line is deep, does the existing easement on
the north provide adequate workinG space for implementing trench
safety?
15. Where the proposed sewer is in the flowline of the creek, and at
shallow depths, consideration should be Given to the backfill
material. Is 85% compaction of native material adequate to prevent
washing out backfill and exposing pipe? Should we consider cement
stabilized backfill?
16. On the Branch I project, TO?O along the south bank of Grapevine Creek
appears incomplete. The lots along the south bank are developed.
17. The sewer capacity and velocities should be indicated on the profile.
18. The City-Wide Storm Water Management Study identifies several
drainage/erosion improvement projects alonG Grapevine Creek.
Consideration should be given to completing those projects
concurrently with this project.
Memo to Shohre Daneshmand
September 30, 1991
Page 3 of 3
19. Sheet SD20 - the table of quantities for Class 4 embedment detail is
incomplete and the trench widths do not match the detail for class 4
embedment.
SPECIFIC COMMENTS
Specific comments are provided in mark-up form on each set of plans.