HomeMy WebLinkAbout1989-11-20 Engineer Review SPR MOD daigle engineers inc
213 brood voy me6ue^,ma 018-44. 508-682-1748 > fax 508-682-6421
San-Lau Realty Trust
231 Sutton Street
North Andover MA 01845
Attn:Anne Messina
August 23, 1989
RE: MESSINA'S MALL
109-125 MAIN STREET,NO.ANDOVER MA
Dear Anne:
Per your request, we have reviewed the earth retention condition at the rear corner of the above
referenced site, The area in question specifically relates to the section which abuts the corner
of the adjacent Housing Authority building near the rear of the liquor store.
Data used by us in formulating our recommendations were:
1. Information taken and observations made during a visit to the site on 8/21/89.
2. Information taken and observations made during a visit to the"PIaza One Fourteen"in Lawrence
on 8/21/89 viewing the existing rip-rap wall. This is the wall that was referenced in the
7/17/89 letter from the North Andover Planning Board;item#3.
3. Review of photos showing different stages of construction of the Housing Authority building.
4. Information furnished by yourself and architect Eric Brainerd.
5. Standard Engineering practices and procedures.
Based on a thorough and systematic evaluation of the above referenced data,it is our professional
opinion that a rip-rap wall would be an acceptable device to retain earth at the embankment in
question. Before making this recommendation however,we had to satisfy,in our mind,the following
conditions:
a. That the loss of gravel (crushed stone) noted at the Lawrence site was not a structural
condition.
b, That this proposed system will not undermine or weaken the ground supporting the Housing
Authority's abutting building.
San-Lau Realty Trust page 2 of 3
109-125 Main Street,North Andover MA August 23, 1989
In viewing the rip-rap wall at the Lawrence site we could appreciate the North Andover building
inspector's concern with regard to the washed out areas that developed. Upon review of the
recently submitted construction detail of this rip-rap wall, however we were relieved to see that
the washed out material (crushed stone) was not a structural part of the wall. The boulders and
the 3" crushed rock behind the boulders are what supports the soil. In addition to this, a filter
cloth was supposedly provided beneath the 3" rock to prevent washout of the soil through the
stone. The washout experienced at Lawrence solely effected the 3/4"crushed stone that was added
by the owner to fill the face voids between the boulders. This was not part of the structural
system. This superficial washout would probably not have happened if excess water did not funnel
into the wall from the adjacent property.
With regard to possible undermining of the adjacent Housing Authority building, it is our belief
that the bottom of the footing at this location is situated at elevation 96'-0". This observation
was made based on photos showing a T-O" high foundation wall at this location. With this being
the case, the proposed rip-rap wall will not encroach or weaken the soil which supports the
abutting building. The work will fall outside of the influence lines of the supporting soil which
radiate outward and downward at a 30 degree angle (from horizontal) from the edge of the existing
footing.
After reviewing the factors effecting these two items (A and B) we feel that there will not be a
problem with a rip-rap wall at this specific installation,
* * RECOMMENDATIONS
Attached is a detail(SK-1) showing the construction that we recommend for the rip-rap wall. This
is a common detail in use today. Before this work is started however, surface runoff from the
Housing Authority site must be cut off. It is our feeling that the roof gutter system is grossly
insufficient to handle the amount of runoff from the roof. In addition to this, the downspout
makes multiple turns and runs horizontally. At the end of this rectangular horizontal run, it
connects into a section of circular PVC and discharges on the ground. This discharge is evidently
making its way back to the embankment, causing erosion. During a heavy rain, it is also evident
that the gutter is backing up and the runoff is overflowing directly onto the embankment. To
correct this, a properly designed gutter system must be provided to handle this flow and the down
spouts must be connected to an approved storm drain system.
Once the above mentioned work is completed we feel confident that this wall system will provide
many years of service. In conjunction with this work however,we do recommend than the following
precautions be implemented:photographs should be taken of the existing foundation and it shall be
San-Lau Realty Trust page 3 of 3
109-125 Main Street,North Andover MA August 23,1989
thoroughly viewed by both parties prior to commencing the work. Any cracks that presently exist in
the walls in this area shall be noted. This is a precaution to insure that pre-existing cracks are
not considered to be recently caused by the proposed work. It is also recommended that the voids
between the large stones of the rip-rap wall not be filled with material. This will alleviate the
problem that developed in Lawrence.
If we may be of further assistance, please feel free to contact us.
Sincerely yours,
Daigle Engineers Inc
Robert K. Daigle,P.E.
President/Structural Engineer
RKD/dhn
Enclosure: SK-1
x/c: Eric Brainerd
FILE NAME:SAN•LAU/Pt•2
1
i'
rro ROBERT
l KEN14FTIH
DAEGLE
Na.28D Q
�'►vtv
REFER TO ATTACHED LETT, 6Y
DAIGLE ENGINEERS ING. DATED 8/23/89
FACE OF EXISTING
[3UILO INC.
P
TOP OF SLOP
ELEV. €0 I'-6"- I �
• 0 4
3'-0" (.6„) DIAMETER o
5OULOER5 (TYP.)
' 3 INCH
o D IAW `ER
1 a CRUSHED.
a ROCK.
I a - •'
o I
oa
Q I MAX. EI55 V, ,,
`I6-0"
' (VEK IFY)
O ' o•
I'-0" {MIN.)
,
4
FILTER FABRIG
o ' i MIKAFI 60OX OR
° - APPROVED EQUAL.
EXISTING GRAVEL
FINISHED GRADE GENERAL NOTES`
ELEV. 91'-6"
€. WORK SHALL 13E DONE
IN €0'-0" 5EGTl0N5 TO
MINIMIZE EXPOSURE OF
EXISTING FOUNDATION.
J"
5 E G T I O U
2. WORK SHALL NOT
COMMENCE UNTIL SURFACE
(3/8" , I'-0") RUNOFF WATER GAN DE
PERMEMANTLY DIVERTED
FROM THE SLOPE.
3. WORK SHALL COMPLY WITH
THE MA55. fiUILDING
CODE.
4. VERIFY ALL DETAILS AND
D IMEN510N5 PRIOR TO
G0N5 TKUG T I ON.
PROJECT: JOB NO.:
5AN- LAU REALTY TRUST 89212
d a i g l e engineers I n c ME551NA'5 MARKET ATE:
213 Broadway methuen,ma 01844 109- I25 MAIN STREET N. AND. 6/23/89
508-682-1748 , fax 508-682-6421 DRAWN BY: DESIGNED BY: C CK BY' SKETCH NO.:
WGA i RKD . 5K - I