HomeMy WebLinkAbout13 Development Permit 307 Parkway View AdditionFrom:
To:
Date:
Subject:
Kent Laza
SVOLK, JKEE
1/16/96 8:53am
I I
Joe Courtney -Parkway View Duplexes -Reply
Don't let Joe mislead you that everything was held up because of detention
requirements. Last month they were ·given two options on how to proceed and
they could have made the appropriate submittals at that time. Both options
were in accordance with all city standards and requirements. It wasn't until
last week when they came back to us asking for help on these requirements and
we began to look at them again. The agreement I made yesterday basically
relieves them of having to install detention ponds. That in itself will save
Mr. Courtney a lot of money.
What Joey asked for is not at all inappropriate, and unless they can give us
an acceptable reason for not requiring it then we should stand firm. In my
mind we have already given him some relief.
>>> Shirley Volk 01/15/96 04:35pm >>>
Today Joey received a call from Joe Courtney asking to tell him what he had to
do to get C.O. 's on the duplexes he has built in his new 5 lot subdivision.
Joey told him to put up money for the required landscaping and get his
sidewalks poured. Joe didn't like the answer!!!
I knew there had been some drainage questions last week, so I went to Kent to
find out where those questions stood. He explained that as soon as a letter
has been submitted which addresses what they verbally agreed to, the drainage
concerns expressed by "engineering" would be satisfied. Last week Joe called
me to see what I could do to help him get the financial guarantees back that
he put up for infrastructure. That's when I learned that all the
infrastructure had been approved and would be accepted once he either built
the detention or gave the City an acceptable engineer's estimate for the
required detention -then we would release all the guarantee above that
necessary for the detention.
Now to get back to the story at hand regarding the c.o. 's for the duplexes. I
have a question: How did we issue building permits in the first place for
buildings in a subdivision for which the infrastructure had not been installed
and accepted? If the building permits had not been issued, we would not now
be in a position to have to answer the questions about c.o. 's.
Anyway, I called Joe for clarification regarding what he expects from the
City, and he said he has the buildings sold and people are being housed in
motels now because he hasn't been able to get C.O.'s for the buildings and he
has been waiting "X number of weeks or months, or something"! Of course,
it's all the City's fault! Joey had told him he could put up money for the
landscaping to the tune of $10,300 for 3 duplexes, but he doesn't want to do
that because it's the City's fault this is happening -because of the
detention requirements. Also -his sidewalk isn't in, but "I can get that in
immediately" once the detention has been answered.
He wants to know if the City can do anything to give him some relief, and my
thoughts are, if he was issued a building permit before we should have,
perhaps the City has already helped him! Of course, that can't be the answer
because if we made a mistake, it's our mistake, and he would have contracts on
the buildings he must fulfill.
Does anybody receiving this mail have some insite as to what I should be
telling Joe -or any relief for his problems? Without knowing the whole
story, I think Joey's answer is the only one we can give him. Please reply to
this one way or another. Thanks.
CC: JDUNN, VMORGAN, SKUENZEL, NTHOMAS
'
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
Sanitar Sewer Im rovements •
~qn,·,)' ~'~~ ~;j·l·~•r•ll ' 1"5::1if11>.1I·'• ijl1\: :. ..... 1~1 .. ~.11~"
. ~~~ ;. '" .oi.\!.;.o.LuJ.i.~ • . ~ lt'tJ.~ _: 1
.G i~j
1. 8" Class 52 Ductile Iron Sanitary 337 L.F . $17 .00
Sewer Line (0 -5 feet)
2. Standard Manhole (0 -8 feet depth) 2 Ea. $1 ,000.00
3 . Open Cut And Replace Existing 1 L.S . $500.00
Concrete Allev
4. Tie Int o ExistinQ Manhole 1 Ea . $350.00
Total Estimated Cost For Sanitary Sewer Improvements:
1. Tie Into Existin 8 " Water Line Ea . $350.00
2. 8 " M .J . Gate Valve and Box 1 Ea. $450.00
3 . 8" Diameter C900 Class 200 P.V.C .
Water Line O -5 feet 218 L.F . $17.00
4. 8" M.J . Plu Ea . $100 .00
5. 8"X8"X2 " M. J . Tee 2 Ea . $250.00
6. 2" Diameter Service Line 15 L.F . $14.00
7. 8"X2 " M .J . Ta in Saddle 1 Ea . $1,500 .00
Total Estimated Cost For Water Improvements :
·111hHl!I
$5,729 .00
$2 ,000.00
$500.00
$350.00
$8 ,579 .00
$350.00
$450.00
$3 ,706.00
$100.00
$500.00
$210 .00
$1 ,500 .00
$6 ,816.00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
(continued)
1. Install 2" Electrical Conduit 1 L.S . $5 ,890.00
2. Bores 1 Ea. $800 .00
Total Estimated Cost For Electrical Improvements:
Summary:
Total Estimated Cost For San itary Sewer Improvements:
Total Estimated Cost For Water Improvements:
Total Estimated Cost For Electrical Improvements:
Total Estimated Cost:
$5 ,890 .00
$800 .00
$6 ,690 .00
$8 ,579.00
$6 ,816 .00
$6,690.00
$22,085 .00
1.
2.
3.
4.
Preliminary Engineer's Estimate
For (
Sanitary Sewer Improvements ~ /__ pfl i
To ~--::? /
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
August, 1995
Estimated Unit Estimated
Quant it Unit Price
8" Class 52 Ductile Iron Sanitary 327 L.F . $17.00 $5 ,559.00
Sewer Line O -5 feet
Standard Manhole 0 - 8 feet de th 2 Ea. $1 ,000 .00 $2 ,000 .00
Open Cut And Replace Existing L.S . $500 .00 $500 .00
Concrete Alie
Tie Into Existin Manhole Ea . $350 .00 $350 .00
Total Estimated Cost For Sanitary Sewer 'Improvements: $8,409.00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
Sanitar Sewer Im rovements· I . ' ' '~illttf-1!"' • I ii I ' I ( ) 11 \, J~ ~ ~;i.1~1·)~r·~· -· i!llH-il·'o
' ~; ~., !l~U 11 ~ tr. •J111,~;J~·
1. 811 Class 52 Ductile Iron Sanitary 337 L.F. $17 .00
Sewer Line (0 - 5 feet)
2 . Standard Manh ole (O -8 feet depth) 2 Ea . $1,000.00
3 . Open Cut And Replace Existing 1 L.S . $500.00
Concrete Allev
4. Tie Into Existing Manhole 1 Ea. $350 .00
Total Estimated Cost For Sanitary Sewer Improvements:
1. Tie Into Existin 8 11 Water Line 1 Ea. $350.00
2. 8" M.J . Gate Valve and Box 1 Ea. $450.00
3 . 8" Diameter C900 Class 200 P.V.C.
Water Line O -5 feet 218 L.F. $17.00
4 . 811 M .J . Plu 1 Ea . $100 .00
5. 8"X8"X2" M. J . Tee 2 Ea. $250 .00
6. 2" Diameter Service Line 15 L.F. $14.00
7. 8"X2 " M .J . Ta in Saddle 1 Ea. $1 ,500.00
Total Estimated Cost For Water Improvements:
• ~ 11l•1lI11
$5,729.00
$2,000.00
$500.00
$350.00
$8 ,579 .00
$350 .00
$450 .00
$3 ,706 .00
$100.00
$500.00
$210.00
$1 ,500.00
$6,816.00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
(continued}
1. Install 2 " Electrical Conduit 1 l.S . $5 ,890.00
2 . Bores 1 Ea. $800.00
Total Estimated Cost For Electrical Improvements:
Summary:
Total Estimated Cost For Sanitary Sewer Improvements :
Total Estimated Cost For Water Improvements :
Total Estimated Cost For Electrical Improvements :
Total Estimated Cost:
$5 ,890.00
$800.00
$6 ,690.00
$8 ,579 .00
$6 ,816.00
$6 ,690.00
$22,085.00
. CONSUL TING ENGINEERING & LAND SURVEYING
4444 CARTER CREEK PKWY, SUITE 108 BRYAN, TEXAS 77802 1409J 846-2688 1409J 846-3094
December 15 , 1995
Mr. Kent Laza, P.E .
City E ngineer
P.O. Box 9960
College Station, Texas 77842-9960
RE: Drainage Report For Lots 1-5, ntock One, Parkway View Addition, Crawford Burnett
League -Abstra ct No. 7, College Station, Brazos Co unty, Texas.
Dear Kent,
The above refe ren ced proj ect consists of th e ~stab li s hm e nt 0f five (5) dupl ex lots . (See enclosed Exhibit
"A" -F inal Plat). Currently duplexes are bei ng constructed on Lot 1, Lot 2 and Lot 5 with construction on
th e remain in g l ots anticipated to commence shortly .
Currently U1 e subj ec t tract along wiU1 approximately 22.L.9 acres of property adjacent to U1e subject trac t
drain to t11 e sou U1 east to SouU1west Parkw ay where sa id rnn-off i s intercepted by Southwest Parkway and
direc ted to an ex i sting pond common l y known as Walden Pond in co njunction wiU1 Walden Pond
Townhomes which lie adjacent and to U1 e nor U1 eas t of same pond. (See enclosed Exhibit "B" -
Topographic Map Of Subject Tract A nd Vicinity).
Prior to U1 e plat tin g of tile subject trac t sam e tract was covered wi tll weeds and U1ick bermuda grass wiU1 a
few sca ttered trees and clump s of bru sh located at t11 e north ern mo st reac hes of tl1e property adjacent to
W oods man Drive. The subj ec t proper ty slop ed away from tl1 e ex i sting 20' concrete alley located at the r ear
of U1e prop erty to SouU1west Parkway. Average grades were 1.00 % from U1 e alley to n ear U1 e 25' building
line along Sout11west Parkw ay whl!re U1 e grat.l e change abruptly to appro x imately 15 % to ilie edge of tile
existi ng 4 ' co ncrete sidewal k runnin g al ong the norU1 wes t sid e of Soutllwest Parkw ay. The
predeve lopm ent nm -o ff coefficient ("c") for l11 e subj ec t site was ass um ed to be 0.40.
The post deve lop ment run off coeffici ent ror t11 e subj ec t tra ct ·.vas determ med by assuming all five (5)
duplex lo1s being deveinpet.l with duplc xl·s represe n tative of tl1e U1ree (3) duplexes currently being
consu-ucted, eac h duplex wi U1 it s own sidewalks and parking area s. As a res ult of tile tll eore tical
development of U1 e subj ec t prop erly Li11:: pu st development run-off co effici ent for t11 e subj ec t tract was
projected to be 0.63.
The es timated total draina ge <u-ea (":\") of interest to tilis r eport inclusive of the subject 1.07 acre tract is
23.36 acr es. Based on t11 e topography ant.l gro und cove r t11 e Lim e of coucentration ("t/c ") was estimated to
he 14.58 minutes. F rom Ex hibit "B" ·To po graphi c Mnp Of Subject Tract And Vicinity, it can be seen U1at
the most hydrau li cal ly di stant meas urement is approximatel y 1750 feet.
Assuming a run -off velocily of 2 fee t pe r second Lh e tim e of concentration is calculated as follows:
1750 feet 875 seconds
---------------= 87S seco nd s a nd ;
2 .00 fl I sec .
--------------------= 14.58 minutes
60 second s
T heoretical s torm intensiLies were generated utili zing Lh e equatio ns depi cted in "F ig ure ITI -1 -In te ns ity
DuraLion Fre(Juency C urv es For The Cily Of College Station". (See Exh ibit "C") based on Lh e a bove
calcul a ted Lim e of co nc e ntratio n of 14 .5 8 minuLes . A tabulati on of Lh e proj ec ted intens iti es is as follows: J!
2-year return frequency: 5 .27 inches I hour -\._~......_ tf
5-year reL urn frequency: 6.46 inch es I h o ur '-' . r." / _)
10-year return frequency: 7.29 inch es I hour "!> ,rP "I: )ti
25-year relurn frequency: 8.34 inch es I hour /.
50-year re turn frequency: 9.45 inches I hour > . ~ ~ ~ ~? l
100-year re turn frequency: 9.8 6 inch es I hour ~:> L~,< ~ ti.h to.~(o l\'\ f ~r
\\' ~~ tl-1>fq.8{bt»}hr
A compariso n to determine Lhe "impact" of Lh e subj ect prop e rt y being deve loped verses undeveloped was
ascertained by em plo yin g Lh e Rational Melhod (Q = c ia) to compute p e~!k di sc harge rates for Lh e total
dra in age are of 23 .36 acres (1.07 acre tr ac t includ e d t11 ere in ) wilh t11 e s ubj ect tract run-off coefficient
ass um ed Lo be 0.40 (und evelo ped). The we ig hted run -off coefficients for Lh e 23 .36 acre drainage area wit11
bolh t11 e 1.07 acre tr act b ei ng und eveloped and developed is comp uted as fo ll ows:
Cwt (1.07 acre tract undevelop ed):
./ ,/ / ./
(11. 79 acres develo ped x 0.q3) + ( 11 .57 ac res und eve loped x 0.40)
23.36 ac res
Cwt (1.07 acre tract dev elop ed):
(12 .86 acres developed x 0.63) + (10.50 acres undeveloped x 0.40)
23.36 acre s
The total p eak discharge rates anticipated for tb e subj ect tract unde ve loped and developed is co mputed
based on Lh e Rational Met110d as mentioned a bove as follows:
Peak Discharge Rates
(1.07 acre tract undeveloped):
2-year re Lurn storm:
5-year re Lurn storm :
10-year ret urn storm:
25 -year re Lurn s torm :
50-year return stonn :
100-year return storm :
( 0.52) x (5 .27 inch es/ hour) x ( 23.36 ac res)
( 0.52 ) x (6.46 inches/ hour) x ( 23.36 acres)
( 0.52 ) x (7 .29 inches/ hour) x ( 23.36 acres)
( 0.52) x (8.34 in c hes/ h o ur) x ( 23.36 ac res)
( 0 .52) x (9.45 in c hes/ h o ur) x ( 23.36 acres)
( 0.52) x 9.86 nches/ h our) x ( 23.36 acr es)
?
= 64.0 ft3/sec .
78.5 ft3/sec.
= 88.6 ft3/sec.
= 101.3 ft3/sec.
= 114 .8 ft3/sec.
119.8 ft3/sec.
"
Peak Discharge Rates
(1.07 acre tract developed):
2-year re Lurn sLo rm : ( 0 .53) x (5.27 inches/ h our ) x ( 23.36 acres) = 65.2 ft3/sec.
5-year re Lurn s torm : ( 0 .53) x (6.46 in c hes / hour) x ( 23.36 acres) = 80.0 n3/sec.
10-year reLum sto rm : ( 0.53) x (7 .29 in ches / hour) x ( 23 .36 acres) = 90.3 ft3/sec.
25-year reLum storm: ( 0.53) x (8 .34 inches/ hour) x ( 23.36 acres) = 103.3 ft3/sec.
50-year re Lurn sLO rm: ( 0 .53) x (9.45 inch es / hour) x ( 23.36 ac res ) = 117.0 ft3/sec .
100-year re lurn s torm: ( 0.53) x ~ches/ hour) x ( 23.36 acres) = 122.1 rt3/sec.
?
A co mpari so n between Urn peak di sc harge rates assoc iated wi th the subj ect 1.07 acre tract undeveloped
and developed is presented as follows:
Storm Return Prede velopm e nt Peak Po s t.d evelopm ent Peak Increase In Peak
F req uency Di scharge RaLes Discharge R a tes Di scharg e Rates
2-year: 64.0 ft.3/Sec. 65.2 ft.3/sec. 1.2 ft.3/sec.
5-year: 78.5 n31sec. 80.0 ft.3/sec. 1 .5 rt3/sec
10-year: 88.6 ft.3/S ec. 90.3 ft.3/sec. 1.7 rt3/sec
25-year: 101.3 n 31sec. 103.3 ft 3/sec. 2.0 n3/sec.
50-year: 114 .8 ft.3/Sec. 1 17 . 0 ft.3 /sec. 2.2 n3 /sec .
100-yeru·: 1l 9.8 fL3/S ec. 122.] n3 /sec. 2.3 ft3/sec .
\As cru1 be seen from th e tabulalion above th e increase in s to nn water peak discharge rates as a function of
U1 e 1.07 acre tr act be in g und evelo ped or developed makes ve ry litU e impact to th e ex istin g drain age
condi tion s a ssoc iated with U1 e 23 .36 ac re drainage basin of whi c h Urn s ubject 1.07 ac re tract is in cluded .
Wa ld e n Pond was not des igned as a re tention facility. Wald eu Pond Townhomes were constructed around
th e al ready existin g "s tock pond" a nd "b ea utificatio n" measures were take n to enh a nc e the aes th etic s as
we ll as the co nstruc tion of a n "improved" s pill way add ed for a n increased factor of safe ty against s torm
wa ter breachin g th e ex istin g darn when sru n e townhomes were con s tructed. The spillway cres t is
cons tructed to e levation 322.9 . The s pill way cre s t e levati on al low s for th e protection of th e existing
dw e llin gs located in th e townhome development from U1 e rru1 ge of storms co n tain ed herein .
Walden Pond does po ssess so me detention I re te nti on qualiti es above th e normal pool stage (estimated to
be at elevati o n 321.6 ), however during U1 e sto rm ran ges in clud ed in thi s re port th e spillway will flow
allowing e xcess run-o ff to pass over U1 e ex istin g dam and into U1 e well defined creek channel below th e
dam which run s to and tl1 en und er F. M. 28 18 to th e so uth.
The ex is tin g spillway geo me try can readily hru1dl e th e proj ected increase in run-off as anticipated with th e
1 co mpl ete develo pm e nt of th e s ubj ect 1.07 acre tr ac t. Develo pm ent anticipated in th e future within the
' 23 .36 acre drainage ba sin wo uld req uir e Urnt Walden Pond be modifi ed and utilized as a reg ional
.._!ete nti o n facility.
In summation th e deve lopm e nt of the subject 1.07 acre tract will produce minor increases to the existing
peak discharge rates within th e 23.36 acre drainage basi n , however th e downstream infras tructure can
abso rb same impact wiU1 little or no noticeabl e in crease in storm water volume or depth.
I hope this letter will serve your needs, how ever, if you hav e any additional ques tion s or problems with the
items contained he re in , pl ease contact me at your earli es t convenience (409) 846-2688.
From:
To:
Date:
Subject:
Kent Laza
SVOLK, JKEE
1/16/96 8:53am
Joe Courtney -
I f
Parkway View Duplexes -Reply
Don't let Joe mislead you that everything was held up because of detention
requirements. Last month they were ·given two options on how to proceed and
they could have made the appropriate submittals at that time. Both options
were in accordance with all city standards and requirements. It wasn't until
last week when they came back to us asking for help on these requirements and
we began to look at them again. The agreement I made yesterday basically
relieves them of having to install detention ponds. That in itself will save
Mr. Courtney a lot of money.
What Joey asked for is not at all inappropriate, and unless they can give us
an acceptable reason for not requiring it then we should stand firm. In my
mind we have already given him some relief.
>>> Shirley Volk 01/15/96 04:35pm >>>
Today Joey received a call from Joe Courtney asking to tell him what he had to
do to get C.O. 's on the duplexes he has built in his new 5 lot subd i vision.
Joey told him to put up money for the required landscaping and get his
sidewalks poured. Joe didn't like the answer!!!
I knew there had been some drainage questions last week, so I went to Kent to
find out where those questions stood. He explained that as soon as a letter
has been submitted which addresses what they verbally agreed to, the drainage
concerns expressed by "engineering" would be satisfied. Last week Joe called
me to see what I could do to help him get the financial guarantees back that
he put up for infrastructure . That's when I learned that all the
infrastructure had been approved and would be accepted once he either built
the detention or gave the City an acceptable engineer 's estimate for the
required detention -then we would release all the guarantee above that
necessary for the detention.
Now to get back to the story at hand regarding the C.O. 's for the duplexes. I
have a question: How did we issue building permits in the first place for
buildings in a subdivision for which the infrastructure had not been installed
and accepted? If the building permits had not been issued, we would not now
be in a position to have to answer the questions about C.O.'s.
Anyway, I called Joe for clarification regarding what he expects from the
City, and he said he has the buildings sold and people are being housed in
motels now because he hasn't been able to get C.O. 's for the buildings and he
has been waiting "X number of weeks or months, or something"! Of course,
it's all the City's fault! Joey had told him he could put up money for the
landscaping to the tune of $10,300 for 3 duplexes, but he doesn't want to do
that because it's the City's fault this is happening -because of the
detention requirements . Also -his sidewalk isn't in, but "I can get that in
immediately" once the detention has been answered.
He wants to know if the City can do anything to give him some relief, and my
thoughts are, if he was issued a building permit before we should have,
perhaps the City has already helped him! Of course, that can't be the answer
because if we made a mistake, it's our mistake, and he would have contracts on
the buildings he must fulfill .
Does anybody receiving this mail have some insite as to what I should be
telling Joe -or any relief for his problems? Without knowing the whole
story, I think Joey's answer is the only one we can give him. Please reply to
this one way or another. Thanks.
CC: JDUNN, VMORGAN, SKUENZEL, NTHOMAS
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
s "t s • t
:nn,·,) ~;-~ ~ ... ,.1.)i"•l• . i":l.,;. fi 1t.H-'> iil1i1 :_. 1 ~I td II:•
''• • _1..>:L ... , • ..'.:'..l.~~J.U fo. ' ~hll~_:·.1 ~~;
1. 8" Class 52 Ductile Iron Sanitary 337 L.F . $17.00
Sewer Line (0 -5 feet)
2. Standard Manhole (O -8 feet depth) 2 Ea. $1,000.00
3. Open Cut And Replace Existing 1 L.S. $500 .00
Concrete Alley
4. Tie Into Existinq Manhole 1 Ea . $350 .00
Total Estimated Cost For Sanitary Sewer Improvements:
1. Tie Into Existin 8 " Water Line 1 Ea . $350 .00
2. 8" M.J . Gate Valve and Box 1 Ea . $450 .00
3. 8" Diameter C900 Class 200 P.V.C.
Water Line O -5 feet 218 L.F. $17 .00
4. 8" M.J. Plu 1 Ea. $100.00
5. 8"X8"X2" M. J. Tee 2 Ea. $250 .00
6. 2" Diameter Service Line 15 L.F . $14 .00
7. 8"X2" M.J. Ta in Saddle Ea . $1,500 .00
Total Estimated Cost For Water Improvements:
·I 11l•~1i1\
$5,729 .00
$2,000 .00
$500.00
$350.00
$8 ,579.00
$350.00
$450.00
$3,706 .00
$100 .00
$500 .00
$210 .00
$1 ,500 .00
$6 ,816 .00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
(continued)
1. Install 2 " Electrical Conduit 1 L.S. $5,890.00
2. Bores 1 Ea . $800.00
Total Estimated Cost For Electrical Improvements:
Summary:
Total Estimated Cost For Sanitary Sewer Improvements :
Total Estimated Cost For Water Improvements:
Total Estimated Cost For Electrical Improvements:
Total Estimated Cost:
$5,890.00
$800 .00
$6,690 .00
$8,579.00
$6,816.00
$6,690.00
$22,085.00
Preliminary Engineer's Estimate
For (
Sanitary Sewer Improvements ~ /'__ pfl 1
To ~':? /
Lots 1 - 5 , Block One -Parkwa View Additio
College Station, Brazos County, Texas
August, 1995
Estimated Unit Estimated Amount
Quant it Unit Price
1. 8" Class 52 Ductile Iron Sanitary 327 L.F. $17 .00 $5,559 .00
Sewer Line O -5 feet
2. Standard Manhole 0 - 8 feet de th 2 Ea . $1 ,000 .00 $2 ,000 .00
3. Open Cut And Replace Existing L.S . $500 .00 $500.00
Concrete Alie
4 . Tie Into Existin Manhole Ea . $350 .00 $350.00
Total Estimated Cost For Sanitary Sewer lmprovements: $8,409.00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
s "t s I t
' i ( ) II\ J"). /;.-j(lf•)~~·~· ' '~1il Ill· I(• • -l1ii :., Hl11t.1l·'t
1 ~'t (. l .,!.J..!JJ II fo•. \;J1ll1,.~;.,l~
1. 8" Class 52 Ductile Iron Sanitary 337 L.F. $17 .00
Sewer Line (0 - 5 feet)
2 . Standard Manhole (O -8 feet depth) 2 Ea . $1,000 .00
3 . Open Cut And Replace Existing 1 L.S . $500 .00
Concrete Alley
4 . Tie Into ExistinQ Manhole 1 Ea . $350.00
Total Estimated Cost For Sanitary Sewer Improvements:
1. Tie Into Existin 8 " Water Line 1 Ea. $350 .00
2. 8" M .J. Gate Valve and Box 1 Ea. $450 .00
3 . 8" D iameter C900 Class 200 P.V.C.
Water Line O -5 feet 218 L.F. $17.00
4. 8" M .J. Plu 1 Ea . $100 .00
5. 8"X8"X2 " M . J . Tee 2 Ea. $250 .00
6. 2" Diameter Service Line 15 L.F. $14 .00
7. 8"X2 " M .J . Ta in Saddle Ea . $1,500 .00
Total Estimated Cost For Water Improvements:
• 111l•J1111
$5,729.00
$2 ,000.00
$500.00
$350 .00
$8 ,579 .00
$350 .00
$450.00
$3 ,706.00
$100.00
$500.00
$2 10 .00
$1 ,5 00 .00
$6 ,816.00
Engineer's Estimate
For
Sanitary Sewer, Water and Electrical Improvements
To
Lots 1 -5, Block One -Parkway View Addition
College Station, Brazos County, Texas
October, 1995
(continued)
1. Install 2" Electrical Conduit L.S . $5,890.00
2 . Bores 1 Ea. $800.00
Total Estimated Cost For Electrical Improvements:
Summary:
Total Estimated Cost For Sanitary Sewer Improvements:
Total Estimated Cost For Water Improvements:
Total Estimated Cost For Electrical Improvements:
Total Estimated Cost:
$5,890.00
$800.00
$6 ,690.00
$8,579 .00
$6,816.00
$6,690.00
$22,085.00
-
E ~I GI ~IEE RI ~I G
. CONSULTING ENGINEERING & LAND SURVEYING
4444 CARTER CREEK PKWY, SUITE 108 BRYAN, TEXAS 77802 l4091 846-2688 (4091846-3094
December 15 , 1995
Mr. Kent Laza, P.E.
C ity E nginee r
P.O. Box 9960
College Station , T exas 77842-9960
RE: Drainage Report For Lots 1-5, Ulock One, Parkway View Addition, Crnwford Burnett
Leagu e -Abstract No. 7, College Station, Brazos County, Texas .
Dear K ent,
The above r efe r en("ed proj ec t cons i sts of th e P.stab li shm ent 0f five (5) dupl ex lo ts. (See encl osed Exhibit
"A" -F inal Plat). Currentl y dupl exe s are bein g cons tructed on Lot 1, Lot 2 and Lot 5 with construction on
th e r emainin g l ots anticipated to commence shorll y.
Cu rrenlly l11 e subj ec t tract along wit11 approxim ate l y 22 .'.l9 acres of prop erly adj acent to th e subj ec t tra ct
drain to l11 e so ut11 eas t lo So ut11 west Parkw ay where sa id run -o ff is inter cepted by Southwest Parkway and
direcLed to an ex i stin g pond commo nl y known as Walden Pond in co njunction wit11 Walden Pond
Townhomes which lie ad j ace nt and to U1 e norU1 eas t of sam e pon d. (See encl osed Exhibit "B" -
Topographi c Map Of Subj ec t T ra ct And Vicin ity).
Prior to th e platting of t11 e subj ec t trac t sam e trai::t was rnvered w it11 w ee ds and thi ck bennuda grass witll a
few sca ttered trees and clumps of bru sh located at t11 e north ern most reac hes of th e property adj acent to
W oo dsman Dri ve. The subj ec t prop erty sloped away from t11 e ex i sting 20' co ncrete alley located at the r ear
of th e prop erty to So uthwes t Parkway. Avcrn ge grades were 1.00 % from U1 e alley to n ear Ul e 25' building
line along Sout11w es t Prn·k way wh~re U1 e gra ue cha nge abruptly to appro ximately 15 % to Ul e edge of Ul e
ex i stin g 4' co ncreLc si dewa lk runnin g al ong U1 e norLhwest side or Southw es t Parkway. The
predeve l opment nm-off coeffici ent ("c") for t11 e subj ec t site was ass um ed to be 0.40.
The po st deve lopm ent run off co e ffici ~nl ror th e subj ec t trac t ·..vas detennmed by ass uming all fi ve (5)
duplex lo1s bein g deve inpeu w it h ouplc xes represe ntati ve of th e three (3) dupl exes currently being
constructed, eac h duplex wi th il s own sidewa lks and parkin g area s. As a res ult of Ul e th eoretical
development of U1C subj ect property U1 c: pu st cl eve lopm ent run-off co effici ent for t11 e subj ect tract was
proj ec ted l o be 0.63.
The es timated Lotal drainage cu·ea (":\")of inlerest to thi s r eport inclu sive of the subj ect 1.07 acre tract i s
23.36 acr es . B ase d on t11 e topo graphy an d ground co ver l11 e Lim e of co11(;entrntion ("tic") was estima ted to
he 14 .58 minutes. F rom Ex hibit "B" -Topographic Map Of Subj ect Tract And Vicinity , it can be seen th at
l11 e most hydrau lical l y Lli stalll meas urement i s Cl pp rox ima1 el y 1750 fee t.
Assuming a run -off ve loci Ly of 2 fee t pe r second Lhe time of concen tration is calcul a ted as fo ll ows:
17 50 feet
= 87'i sec ond s a nd ;
2 .00 fl I sec .
875 seconds
--------------------= 14.58 minutes
60 seconds
T heoreLi cal storm inte ns iti es were genera ted ulili z in g the equatio ns depicted in "F ig ure III-1 -Intensity
Duration F req uency Curves For T he Ci ty Of Co ll ege Station". (See Exhibit "C") based on th e above
calcul ated tim e of concentr ation of 14 .58 minuLes. A tab ul ation of the proj ected inte ns iti es is as fo ll ows: 1!
2-year return fre qu en cy: 5.27 ~nch es I h o ur -..,~ ~"--tf
5-year return frequency: 6.46 mch es I hour " /.)
10-year return freq uency: 7.29 inch es I hour ~ ,:P Yf
25-year return fre qu ency : 8.34 inches I hour /
50-year return frequency: 9.45 inch es I h o ur >. "' ~ ~ ~? l
100-year return frequency: 9 .86 in ches I hour ~:;.~~-nv.l'f"~ t.J .. .a to,&<o \hr ~r
,t l\Jllt'-"s yi.11fq.sco11-1 /hr
A compariso n to determin e th e "imp act" of the subj ec L prop erty being deve loped verses und eveloped was
ascert.ai ned by employing Lhe RaLional Melhod (Q = c ia) to co mpute pef!lc discharge rates for Lh e total
drain age are of 23.36 acres (1.07 acre tract included U1 erein) wi lh U1 e subj ect tract run -off coefficient
ass um ed to be 0.40 (und eve loped). The weighted run-off coefficients for Lh e 23.36 acre drai n age area wi U1
bolh Lh e 1.07 acre tr act being und eveloped imd deve loped is computed a s fo ll ows:
Cwt (1.07 acre tract undevelop ed):
../ ,/ ,/ ./
(11.79 acres developed x 0.(')3) + ( 11.57 acres und eve loped x 0.40)
23.36 acres
Cwt (1.07 acre tract d evelop ed):
(12.86 acres developed x 0.63) + (10 .5 0 acres und e veloped x 0.40)
23.36 acres
The total peak discharge rates anticipated for U1 e subj ect tract undeveloped and developed is co mputed
based on U1 e Rational Melhod as mentioned above as follow s:
Pea k Disc harge Rates
(1.07 acre tract undeveloped):
2-year re Lurn s Lorm: ( 0.52 ) x (5.27 in ch es/ h our ) x ( 23.36 acres) = 64.0 ft3/sec.
5-year reL urn s torm : ( 0.52) x (6.46 inches/ h o ur) x ( 23.36 acres) = 78.5 ft3/sec.
10 -year return sLonn: ( 0.52) x (7 .29 inch es/ hour) x ( 23.36 acres) = 88.6 ft3/sec.
25-year re Lurn s torm: ( 0.52) x (8.34 inches/ h our) x ( 23.36 ac res) = 101.3 ft3/sec .
50-year re Lum s tonn: ( 0.52) x (9.45 inch es / h our) x ( 23.36 acres) = 114.8 ft3/sec.
100-year re turn s torm: ( 0.52) x 9.86 ·n ch es/ ho ur) x ( 23.36 acr es) = 119.8 ft 3/sec.
?
Peak Discharge Rates
(1 .07 acre tract developed):
2-year return s Lo nn : ( 0.53 ) x (5.27 inches/ hour) x ( 23.36 acres) = 65.2 ft3 /sec.
5-year re Lurn s Lonn : ( 0.53 ) x (6.46 in c hes/ hour) x ( 23.36 acres) = 80.0 ft3/sec.
10-year return storm: ( 0.53) x (7.29 in ches / hour) x ( 23.36 acres) = 90.3 ft3/sec.
25-year return storm: ( 0.53 ) x (8.34 in c hes / hour) x ( 23.36 ac res) = 103.3 rt3/sec.
50-year reLurn s Lo nn : ( 0 .53) x (9.45 in c hes / hour) x ( 23.36 ac res ) = 117.0 ft3/sec .
100-year return storm: ( 0.53 ) x ~c h es/ hour) x ( 23.36 acres) = 122.l rt3/sec.
?
A co mpari so n between tJ1 e peak discharge rates associated wi tll tlle s ubj ect 1.07 acre trac t und eveloped
and developed is presented as fo ll ows:
Storm Return Predevelopment Peak Po std evelopm ent Peak Increase In Peak
Freq uency Discharge Rales Discharge R aLes Discharge Rates
2 -year: 64.0 ft 3/Sec. 65.2 ft3/sec. 1.2 ft3/sec.
5-year: 78 .5 ft3/Sec. 80.0 ft3/sec. 1.5 ft3/sec
10-year: 88.6 rt3/Sec . 90.3 ft3/sec. 1.7 ft3 /sec
25 -y ear: 101 .3 rt 3/Sec. 103.3 ft 3/sec. 2.0 ft3/sec .
50 -year: 114.8 ft3/sec . 11 7 .0 ft3 /sec. 2.2 ft3 /sec.
100-year: 119.8 rt3/Sec. 122 .1 rt3 /sec. 2.3 ft3 /sec.
I As cru1 be see n from tll e tabu lation above th e in cr ease in stonn wa ter peak di scharge rates as a function of
tJ1 e 1.07 acre tract be in g und eve lop ed or developed makes ve ry littJ e imp ac t to tll e ex is tin g drainage
co ndition s associated wiU1 tll e 23.36 acre drain age basin of which U1 e s ubj ect 1.07 acre tract is includ ed .
Walden Pond was no t designed as a retention fac ilit y . WaJd e 11 Po nd Townhomes were constructed around
tll e aJready ex isti ng "stock pond" and "beautification" meas ures we re taJ~e n to en hance tll e aes th e tics as
1 well as tJ1 e construction of a n "improv ed" s pill way add ed for a n increased factor of safety against storm
water breachin g tll e ex isLi ng dam when sam e townhomes were con structed . The spi ll way crest is
co n s tructed to elevation 322.9. The spillway cres l e le valion aJ lows for th e prolection of th e ex is ting
dwellings located in tJ1 e townhome development from tll e rru1 ge of s tonn s contain ed here in.
Walden Pond does possess so me detenlion I re tention qualili es above th e nonnal pool s ta ge (estimated to
be a t elevaLion 321.6 ), however durin g tJ1 e s torm ranges in clud ed in thi s re port th e spillway will flow
aJlowing excess run -off to pass over tJ1 e existi ng dam and inlo tll e well de.fined creek channel below tJ1 e
dam which run s to and tJ1 en und er F. M. 28 18 to the so utll.
The ex is tin g spi ll way geometry can readi ly h ru1dle tJ1 e proj ecLed increase in run-off as a nlicipated with th e
comp le te develo pm ent of tll e s ubj ect 1.07 acre tract. Development anticipated in tll e future within tJ1 e
1 23 .36 acre drainage ba si n would require tJrnt WaJct e n Pond be modified and utili zed as a reg ional
~_rete ntion facility .
In s ummati on the development of th e subj ect 1.07 acre tr act w ill produce minor increases to th e existing
peak discharge rates within tJ1 e 23.36 acre drain age basi n , however ili e downstream infras tructure can
absorb sam e impact wi ili littl e or no noticeable increase in stonn water vol um e or deptJ1 .
I hope ilii s lelter will serve yo ur needs, ho wever, if yo u have a ny additional qu es tion s or probl ems with th e
ile ms co ntain ed he rei n, pl ease contact me at your earli es t co nv eni e nc e (409) 846-2688.