Northlake 635(2)-CS 961118November 18, 1996
John Spires
Brockette Davis Drake, Inc.
4144 N. Central Expressway, Suite 1100
Dallas, TX 75204
RE: Lincoln Business Park
Dear Mr. Spires:
The City With A Beautiful Future
P.O. Box 478
Coppell, Texas 75019
214-462-0022
I have received and reviewed the section of your geotechnical lnvestigation provided by
Maxim Technology concerning the pavement recommendations. There are several
recommendations concerning the paving section and subgrade sections .i~ your automobile
area a~..d in the .truck dock area. From reading you.r letter, to me .i~. appears you are
requesting something different than those reco .mmendatlons and are seel~ing approval from
the City of Coppell to install an alternate pawng and subgrade section~ ..Wh?e that is in
accordance with what the City has provided on previous projects, it ty.p~cally is gra~. ted in
situations where the geotechnical firm has not recommended something more stringent.
The main difference I see from Maxim is they are recommending the sul~grade be scarified
and como_acted to an 8" depth, instead of a 6" depth, and reinforcement of #3's on 18"
cent r~is~and~f 24" o.c. and 3500 p~ for truck areas. I am unsure of ~vl hat your letter is
requesKn-~-ih regards to the automobile section, but in the truck section ~,ou are .r. eq ~u. esting
that the concrete be increased from 3500 psi to 4000 psi and that the Ii ne stabilization be
deleted.
The option that the City of Coppell has offered for parking lots is eit her an increase in
thickness by 1" or an increase in strength to 4000 psi. In essence, if 3rou are wishing to
eliminate the lime stabilization and go with 6" paving in your truck areal then the concrete
strength would have to be 4000 psi. Also, if you are wishing to ~liminate the lime
stabilization in your automobile areas, the concrete strength would still have to be 4000 psi
or the thickness would have to be increased by 1". Neither one of ti ese options are as
stringent as your geotechnical firm has recommended. Even though yo~ ar letter alludes to
the fact that they recommend the automobile area without lime subgr:~de, I would draw
your attention to the fact that they do state that a lime stabilized subgr~.de would improve
pavement performance and reduce maintenance. Also, their recommem lations were based
on an 8" scarification and compacted subgrade as opposed to a typi(al 6'". Based on
previous considerations by the City of Coppell, the City will approve your request to
eliminate the lime stabilized paving. However, you need to be fully awa
for all sections has to be 4000 psi or increased by 1" thickness. Please
office of what your desire is in regard to this matter.
If you should have any additional questions please feel free to contact
Sincerely,
Kenneth M. Griffin, P.E.
Director of Public Works/City Engineer
re that the paving
:learly inform thin
his office.