DR9001-CS 910719PACHECO KOC~l
Consulting Engineers, Inc.
Mr. Phll Cullum
Cullum Construction Co.
P.O. Box 84:55
Dallas, Texas 75205
July 19, 1991
PK No: 1004-90.005
Re: Woodside Village (Connell Skaggs Addition)
Drainage Improvements
Dear Phil:
Enclosed is a letter from Alpha Testing Inc. to Mr. Mark Connell, dated July 16, 1991.
This letter outlines specific steps to be taken regarding the backfill of the portions of the
box culvert which are now experiencing ground water encroachment into the excavation
Please proceed with the backfill of the trench as outlined in the attached letter, paying
attention to the cautions regarding trench safety. We would like a letter from the engineer
who designed the trench safety system addressing the use of vibratory equipment in the
trench, prior to proceeding with the work.
If you have any questions regarding this matter, please do not hesitate to call me.
Sincerely,
Jr., P.E.
JAK/tbj
1004-41
Mr. Mark Connell, Connell Dev. Co., w/enc.
Mr. Danny Buckelew, Buckelew Const. Co., w/enc.
Mr. Larry Davis, City of Coppell, w/enc.
9401 LBJ Freeway · Suite 250 ° Dallas, Texas 75243 · (214) 669-1600
SENT BY:ALPHA TESTING
'A
; 9-17-9t
1 214 669 1688;~ I
~uly 16, 1991
COmBBLLD~CO.
BOX 541057
De~laB. Texas 75354-10S?
Attest/oat Mr. Hark Connell
¢oppell, Texas
ALPH~ Report ~o.
003?2-28
Gentlemen:
At the request of az. Jim Koch with Vacheco & Koch, the undersigned
performed a visual observation at the subJec~ site £or the purpose
of evaluating control of water seepage to facilitate coupaction of
backfill against the box culvert walls.At the time this
inspection was performed, portions of the backfill along the
no~thern portion o~ the box culvert had bean placed end colq~acted.
The undersigned met with #r. IMnnmy Buckelew of Buckelew
Construction and Hr. Larry Davis with the City of Coppell at the
Job site. Itwas observed that water seepage had collected at the
exterior base of locutions near weep
the box cu]vert at sever~l
holes formed in the base of the box culvert (southern end). Xt was
discussed that current conpaction of normal backfill soils in areas
where water had collected would be difficult due reputing ~ the
saturated subgrade soils. Danny Buckelev suggested that on site
sand and 9ravel be used initially as backtill and OOlq~cted with
a vibratory roller.
In view of the conditions obeervedt the following recolmendationa
are p~ovided fo~ backfilling the area within 2 ft on either side
o£ the existing weep holes in the subject boa culvert. Please note
that it La intended that the initial 2 ft of backfill in the
excavation be send and gravel enclosed in a filter fabric for the
distance 2 it on either side of the existing Weep holes. According
to conversations wi~h Hr. Jim KOch~ weep holes in the northern
portion of the box culvert hsve alread~ bean backfllled and the
following criteria would apply only ~o veep holes still exposed.
First, it is ~ecommended that the collected water seepage bepunped
from the excavation as much as practi.cal. Reasonable et£orts
should be extended to ~emove any obviously weak soils. A filter
fabric aimila~ to ?ypa~ Style 3401., attar! S0~z, or other as
approved by t~h,e Engineer should be placed in the base of the
excavat:ion ia c~st;ance of st: least 2 ~ on e~he~ s~de of ~a~ weep
hole). The fllte~ fabric should extend up the ~a~ o~ the ~x
c~ve~ and ou~wa~d ~om the ~ace o~. the ~x ~lver2 to ~he
~ankment walls wl~h ez~os ~llter fabric ho en~sulato the
~n~tl~ sand and 9~avel layer. Sand a~ g~avel ~uld then ~
du~ on the filter fabric In a maxln~ single 2-fi ~hick loose
lift. Addi~ional sand and 9~avel ~Y ~ ~ul~ed in a~eao where
~ak 80ils have ~en ~emov~ to p~ide ~e ~il~er fabric en~o~
sand and 9~avel at least 6 ~n~e8 ~ove and ~1~ the elevation of
the veep holes.
The sand and gravel should then be compacted with at least 4 passes
Of a vibratory roller° After co~pection of the sand end 9£avel,
the excess £11ter fabric should be lapped across the top surfece
of the compacted sand end gravel at least 1.S ft and secured.
Other backfill soils placed above this initial send and grevel
layer could consist of native soils compacted in accordance with
the p~oJect specifications. Care should be taken riot to te&~ or
destroy .the fllte~ fabric during the placement o£ additional
backfill° ~t is recommended that a ~epresentative of ALPltA
TtSTING, INC. v~suall¥ observe the placement o~ the filte~ fabric
and co~pactlon of the sand and gravel- ~lxture to assure that the
intent of these recom~endetLon's are achievt~l in the field.
At Intermediate po~nts between'veep holes the filte~ fabric ~ould
not be requ£red. Rather, the initial 2 f~ of backfill could
coriolat of sand and 9ravel compacted with s vibratory rolle~ as
o~tl~ned above.
It should be noted that du~ing the site visit, it was observ~ that
the e~bank~ent slopes seemed unusually steep for the soil
conditions observed. Additionslly~ a dracjline was positioned
of the slopes. Ths:e£ore, it ia our recom~endation that the t~en~
eatery plan and the p~esen~ con~itions in the field ~ r~ie~ by
~alified experts ~o assure ~ha~ sa~e ~nditione are present~'~ore
vo~k~n ente~ the excavation. Further, It ia ~e~mnd~ that the
view of vibrations ~used b~ co.action oS the a~ve 2 ~ o~sand
and g:nyel..~he ~ove ~ecomMndations ~oE tmen~ ~CK~ill ~n o~y
~ tmpleMn~ed provi~ t~en~ safe~y ezpe~s have ~nfi~ safe
We appreciate the opportunity to be of service on th~s project,
2£ we can be of further assistance, please contact or office.
Sincerely. yours.,