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' Final
Drainage Report
for
' THE NAROPA INSTITUTE, PHASE 1
Boulder,Colorado
May 23,2000
5�zsl 2ZC) o
' THE NAROPA INSTITUTE REDEVELOPMENT,PHASE 1
' Final Drainage Report
May 23,2000
1
GI
' Prepared By: CRB Engineering,Inc.
1701 South Valentine Way
Lakewood, Colorado 80228 = ;v 19481 n
(303)980-0245 =9'•,5�,23�00,:\\0��
I Prepared For: Architecture DenverONA\- r-�,
730 17'' Street, Suite 420
Denver,Colorado 80202
(303) 893-160
TABLE OF CONTENTS
' General Location and Description Page 1
' Drainage Basins and Sub-basins Page 2
Drainage Design Criteria Page 3
' Drainage Facility Design—Phase 1 Page 5
' Erosion and Sedimentation Control Page 6
Conclusions Page 6
' Vicinity Map Page 8
Appendix
Drawing 1 —Phase 1 Grading and Drainage Plan
i
' The Naropa Institute Redevelopment,Phase 1
' Final Drainage Report
' General Location and Description
This report presents an analysis of the drainage issues related to the proposed first phase of
redevelopment of the Naropa Institute site.
The site is located along the south side of Arapahoe Avenue between 21"and 22 n Streets in
Boulder, Colorado. Specifically,the site is located in the north half of the northeast quarter of
Section 31, Township 1 North,Range 70 West of the Sixth Principal Meridian, County of Boulder,
' State of Colorado. See "Vicinity Map",page 8. The existing site encompasses a parcel of land
consisting of approximately 3.83 acres. Arapahoe Avenue borders the site on the north,the
' University of Colorado(CU)day care facility lies to the east, an open grassed area, a parking lot for
the CU housing, as well as Marine Street,border to the south, and an apartment complex and
' commercial building border on the west. Boulder Creek is the major drainageway,which passes
west to east, off-site,to the south through the CU property.
' The site currently consists of developed ground with nineteen buildings and associated landscaped
' grounds and parking areas(gravel and asphalt). The site generally drains northwest to southeast at
approximately 1.4%. There are three primary outfall points from the site. A number of locations
' were observed throughout the site that do not provide positive drainage and could cause flooding to
adjacent buildings. There are no apparent public storm sewer systems in the area. A private
' irrigation ditch crosses from west to east adjacent to and along the Arapahoe Avenue frontage. This
irrigation ditch is piped from approximately the eastern third of the site on downstream and off the
' site. No information was available from the City regarding the flows down Arapahoe Avenue. The
site is located within the Boulder Creek drainage basin. A soils report by Ground Engineering was
provided. Soils conditions consist of a thin topsoil layer over natural sand, sandy gravel,and
' gravelly sand. Claystone bedrock was encountered at a depth of approximately 22 feet below the
existing surface. Based on this report, soil group "A", per the Soil Conservation Service(SCS)
' classification system, is assumed.
Phase 1 of the development plan consists of demolishing two existing buildings, building a 6400
square foot building,Nalanda Hall, and expanding the existing parking areas adjacent to the private
' I
drive. A 1,630 square foot building will be torn down to make way for Nalanda Hall. The"tea
house", a 100 square foot building, located on the western side of the site will be torn down and
relocated at the southeast corner of the site. An existing drive runs north to south, through the
' western third of the site, from Arapahoe to Marine Street and ties all the parking areas together.
This drive, along with the associated parking areas adjacent to it,will be removed and replaced in
approximately the same location as they exist now. See Drawing No.1,enclosed, for existing versus
proposed alignment and expansion. The proposed pavement, "grasscrete",will be utilized as a pilot
project to replace the gravel and asphalt pavement surfaces. This product is intended to reduce
runoff due to development as well as enhance the overall water quality from the site. Asphalt
pavement will be utilized down all the drive lanes to minimize traffic impact on the grasscrete and to
' allow for easier maintenance. There is no storm sewer system on or near the site. Detention storage
will not be provided, as approved following the preliminary drainage report submittal. This is due
to the insignificant increase in runoff coefficients and subsequently the resultant runoff. The
proposed improvements will not affect the existing drainage patterns. The composite site
' imperviousness,based on Table 3-1 in the appendix, is approximately 29 percent. The proposed site
imperviousness is approximately 34 percent.
' Drainaee Basin and Sub-basins
' The site is located within the Boulder Creek drainage basin. The major basin that contains the
Naropa Institute is located on the FEMA Flood Insurance Rate Map for Boulder County Colorado
' and Incorporated Areas, Map Number 08013CO395 F, Panel Number 395 of 595, dated June 2,
1995. This map shows that the area is located within a 100-year flood zone. The basin currently
' drains west to east to the St. Wain Creek and on to the South Platte River. The Boulder Creek
Flood Hazard Delineation, By Muller Engineering Company,Inc.,dated January 1983,also
' indicates the site is within the 100-year floodplain.
Development in the area is primarily commercial and residential buildings with facilities associated
with the University of Colorado to the east, south and west. Development in the area does not
appear to have had an impact on the overall historic drainage patterns for this site. However,
development on the CU property appears to have created a low-lying swale along the south side of
the Naropa site,which does not appear to be naturally occurring. In addition,this swaled area does
' not appear to provide a continuous positive gradient to Boulder Creek. Intermittent pooling of water
will occur along the conveyance route through the CU housing to the southeast. These areas will
2
' overflow,then continue on to the creek.
No drainage reports for the offsite developments affecting the site were available. Due to the
' relative insignificance of the changes being made in the parking area and since only minor changes
in the drainage patterns are being made(to develop some degree of minimal standards), a detailed
analysis of runoff for the offsite areas was not considered pertinent at this time. This flow will be
' addressed in the final drainage study for the proposed phase 2 improvements.
Drainaffe Desien Criteria
Methodologies included herein are consistent with the City of Boulder Design and Construction
' Standards(CBDCS)and the Urban Storm Drainage Criteria Manual(USDCM)by Urban Drainage
and Flood Control District.
No relevant design information was found for this site. Runoff from the adjacent development will
need to be accommodated through the site to the existing swaled area on the CU property along the
south property line. This proposed development will accommodate the offsite flows and storm
' runoff from the site will be less than or approximately equal to existing flows. Existing drainage
patterns for this development have not been significantly modified and the existing drainage patterns
' appear to be consistent with available mapping of the area.
' Significant site constraints consist of very flat grades with an overall lack of adequate drainage
throughout the site and surrounding area. The site as a whole is considered sub-standard with regard
to adequate drainage. As indicated above, a number of locations were observed throughout the site
that do not provide positive drainage and could cause flooding to adjacent buildings. This is
especially true in the area of the parking renovation. The design intent relative to the parking area,
with the exception of some minor expansion,was to basically remove and replace the parking
surface with paved drive lanes and grasserete while maintaining the existing grades and drainage
' patterns. However, in an effort to provide some form of safeguard to prevent pools of water from
forming on the surface,which could eventually cause the new asphalt pavement to fail, some
' regrading of the area is proposed. An absolute minimum slope of 1.0 percent was provided on all
new pavements, Concrete pans and curb and gutter are proposed only in those areas where
' concentrated flows are anticipated. A minimum of 0.5 percent gradient shall be maintained on these
structures. Due to the number of existing design constraints,coupled with development and budget
' 3
limitations, deficiencies will remain and the potential for flooding in the area is still a possibility.
However,overall the proposed development is an improvement over the existing condition. These
design parameters and remaining deficiencies were discussed with the architect, City staff, and
' subsequently the owner(through the architect)to clarify and identify restrictions in the design.
Considering the phase 2 portion of development will correct the remaining drainage problems, it
was decided to limit the extent of improvements and deal with the remaining deficiencies as needed
through regular maintenance. Detailed information for the offsite flows from the surrounding
developments were not available, and as discussed above,runoff from the area will be addressed, in
detail, during the final drainage study for the phase 2 improvements.
Runoff for the site has been computed using the Rational Method:
' Q = CIA
Where Q = Storm flow, cubic feet per second(cfs)
' C = Runoff Coefficient
I = Rainfall intensity(in./hr.)
A = Drainage area(acres)
Runoff coefficients were obtained from Table 3-1 from the USDCM. Runoff coefficients for the
"grasscrete"product were determined utilizing a composite"c"value based on a surface area of 47
' percent concrete and 53 percent grass. Detention volumes were calculated for the 10-year storm in
accordance with the CBDCS. Due to the location of the site within the 100-year floodplain and the
insignificant increases in runoff from the proposed improvements,the City of Boulder waived the
1 detention requirement for the 10-and 100-year storms. Design rainfall data was obtained from
Figure 7-1 of the CBDCS. The 5-year and 100-year storms are used for the minor and major storm
' designs.
The design of the storm drainage system conforms to the criteria set forth in the CBDCS. Copies of
pertinent charts and nomographs utilized for design and analysis of the storm sewer system are
included in the appendix of this report. Existing runoff calculations were conducted for those areas
that will impact adjacent development. Flows were checked for these sub-basins to ensure
developed runoff was less than or approximately equal to existing conditions.
' 4
i
Drainage Facility Design—Phase 1
Runoff from the site will be conveyed by surface sheet flow to the existing site outfalls. No storm
sewer piping is proposed for this expansion and existing drainage patterns in this area will remain
unchanged. Within the site,the storm drainage system will be privately owned and maintained. The
enclosed Phase 1 Grading and Drainage Plan,Drawing No.1, in the rear pocket of this report,
illustrates the drainage facility design for this site. The proposed drive and parking areas will utilize
cast perforated concrete paving integrated with recessed grass pods. The main drive lanes will be
paved with asphalt, as shown,to minimize the impact of heavy traffic on the grassed pods. It is our
understanding, runoff from this perforated pavement will approximate that of an ordinary grassed
area, provide erosion protection, and enhance the water quality of the runoff by allowing storm
water to pool and percolate into the subgrade. Based on available information, it appears that by
substituting a gravel filler in place of the typical topsoil and grass, infiltration rates as high as 12
inches per hour can be achieved with the proper subgrade material. This would further reduce
runoff from the area and thereby reduce detention requirements. This perforated pavement is
intended to be used as a pilot project to test the effectiveness of "grasscrete"to reduce excess runoff
due to development.
As indicated above,the City of Boulder has waived site detention storage for the 10-and I00-year
1 storms. Even though the developed areas have been revised from that shown in the preliminary report,
the phase I improvements do not significantly increase storm runoff from the site. Basin E-1/P-1
increases by 0.52 cfs(2.72 cfs to 3.24 cfs)and by 0.90 cfs(7.79 cfs to 8.69 cfs)for the 5-and 100-
year storms,respectively. This increase correlates to a required detention volume of 724 cubic feet
for the 10-year storm. Basin E-2/P-2 increases by 0.01 cfs(0.21 cfs to 0.22 cfs) and increases by
0.09 cfs(0.66 cfs to 0.75 cfs)for the 5-and 100-year storms,respectively. This increase does not
correlate to any detention storage being required for the 10-year storm. Basin E-3/P-3 increases by
0.07 cfs(039 cfs to 0.46 cfs)and by 0.11 cfs(1.31 cfs to 1.42 cfs) for the 5- and I00-year storms,
respectively. This increase correlates to a required detention volume of 149 cubic feet for the 10-
year storm. The maximum increase in flow occurs in basin P-1; however,neither the 5-or 100-year
flows are considered significant changes and will not cause an adverse impact to downstream areas.
In addition, both flows are reduced over what was presented in the preliminary report.
Consequently, a waiver of the I0-year detention requirement for the entire site is still pertinent due
' to the relatively small volumes required and the insignificant change in flowrates.
' 5
Offsite runoff from the west will continue to be conveyed through the site as it does now. There
apparently have not been any significant flooding problems in the past due the offsite flows.
However, as noted above,a number of areas were observed that do not provide positive drainage
throughout the site that may cause flooding to adjacent buildings. These flows will be analyzed in
detail during the final drainage study for phase 2 to determine the quantity of flow and any potential
' hazards the runoff may present.
Except for basin E-3/P-3, existing and proposed runoff from the site is directed toward the swaled
area immediately south of the property and conveyed to the east,through the CU housing area,and
then to Boulder Creek. Basin E-3/P-3 will remain unchanged and discharges to Arapahoe Avenue
near the northeast corner of the site. As indicated above,these flows are less than or approximately
equal to the existing flow rates. In addition,the proposed development will not significantly change
the hydrologic character from its existing state. The flows will leave the site in the same manner as
the existing condition. Consequently,velocities will also be less than or approximately equal to the
existing conditions.
Erosion and Sedimentation Control
Erosion and water quality control during construction will be provided by way of straw bale barriers
at all temporary and permanent outfall locations to provide sediment traps. Silt fencing will be
provided around the perimeter of the construction limits to further mitigate erosion. Vehicle
tracking pads will be provided at the construction access point to prevent the transport of mud and
sediment onto any paved surfaces. All temporary and permanent sedimentation control features
' shall be maintained and repaired on a regular basis during construction to ensure adequate
performance of their intended function, including inspection and repair following each precipitation
1 or snowmelt event that results in runoff. Permanent erosion and water quality control will be
provided by means of grass buffer strips, and grassed swales.
rConclusions
Development of this site will comply with the City of Boulder Design and Construction Standards
and with the USDCM. Erosion and sedimentation control has been addressed herein and will be
provided. This report formulates a storm water management system,which provides controlled
developed peak flows produced by the 5-year and 100-year frequency rainfall. Flows from the site
described herein have been controlled to the development requirements and are consistent with the
6
existing rates. Consequently,the drainage system of the developed site does not appear to adversely
1 affect off-site/downstream areas.
7
Grove St.
a a
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Arapahoe Ave.
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`*4 Marine St.
Project
Site
Athens
Boulder Creek
' VICINITY MAP
Scale: NTS
8
References
iBrater and King,Handbook of Hydraulics, McGraw-Hill Book Company,New York 1976.
Chow, Ven Te, Open-Channel Hydraulics,McGraw-Hill Book Company,New York 1959.
City of Boulder Design and Construction Standards, July 2, 1998.
CRB Engineering, Inc.,Preliminary Drainage Report for The Naropa Institute, dated July 30, 1999.
Muller Engineering Company, Inc., Boulder Creek Flood Hazard Area Delineation, January, 1983.
Wright-McLaughlin Engineers,Inc., Urban Storm Drainage Criteria Manual, Denver Regional
Council of Governments, Denver 1969.
' 9
' DRAINAGE CRITERIA MANUAL RUNOFF
' TABLE 3-1 (42)
RECOMMENDED•RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS
LAND USE OR PERCENT FREQUENCY
SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100
' Business:
Commercial Areas 95 .87 .87 .88 .89
' Neighborhood Areas 70 .60 .65 .70 .80
Residential :
Single-Family * .40 .45 .50 .60
Multi-Unit (detached) 50 .45 .50 .60 .70
Multi-Unit (attached) 70 .60 .65 .70 .80
1/2 Acre Lot or Larger * .30 .35 .40 .60
Apartments 70 .65 .70 .70 .80
Industrial :
Light Areas 80 .71 .72 .76 .82
Heavy Acres 90 .80 .80 .85 .90
Parks, Cemetaries: 7 .10 .18 .25 .45
' Playgrounds: 13 .15 .20 .30 .50
Schools: 50 .45 .50 .60 .70
I Railroad Yard Areas 20 .20 .25 .35 .45
Undeveloped Areas:
Historic Flow Analysis- 2 (See "Lawns")
' Greenbelts, Agricultural
Offsite Flow Analysis 45 .43 .47 .55 .65
(when land use not defined)
Streets:
Paved 100 .87 .88 .90 .93
Gravel (Packed) 40 .40 .45 .50 .60
' Drive and Walks: 96 .87 .87 .88 .89
Roofs: 90 .80 85 .90 .90
Lawns, Sandy Soil 0 .00 .01 .05 .20
' Lawns, Clayey Soil 0 .05 .15 .25 .50
NOTE: These Rational Formula coefficients may not be valid for large basins.
*See Figure 2-1 for percent impervious.
11-1-90
URBAN DRAINAGE AND FLOOD CONTROL DISTRICT ��
' L)HAMAGE CRITERIA MANUAL RUNOFF
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LAND SURFACES IN THE DENVER REGION.
REFERENCE: "Urban Hydrology For Sm411 Watersheds" Technical
Release No. 55, USDA, SCS Jan. 1875.
5-1-84
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CITY OF BOULDER
URBAN DRAINAGE AND FLOOD CONTROL DISTRICT
BOULDER CREEK
FLOOD HAZARD AREA
DELINEATION
v�
January
1983
COMPANY,MULLER ENGINEERING
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+� es URBAN DRAINAGE AND
)ODC JTROL DISTRICT FLOOD HAZARD AREA 01;EUN;ATION BOULDER CREEK SHEEr $
at[ CITY OF BOULDER BOULDER CR FLOOD PLAIN: 1161-10 701141+30 OF 19
ARAPAHOE AVE.,6 JOB NO.8130
MStrmFLOODING SOURCE FLOODPLAIN DATA FLOODWAY DATA
DOSS 1 IOO Tr dNJY11DE TNALWED IQOT F1OpOPLAPI FLOOOWAT •IDTN FLOODWAY
t
swrm STATION (CFS) TLE wrq Mr.FLOOD ELEVGISL) a�MN4R) LEFT Ii TI RRHT(M TOTAL(FT) EtEv.lY9J
25 (36+60) (4200) (5270.3) (5272.0) (700)
26 1121+30 (38+70) 7300 (4200) 5260.1 (5271.8) 5271.2 (5273.2) 760 (910)
27 1126+50 (40+90) 1300 (4200) 5263.7 (5273.4) 5274.0 (5274.8) too 830
28 1130+50 (45+05) 7300 (4200) 5265.3 (5277.0) 5277.4 (5279.3) 5024 (830
25)
29 1134+15 (48+40) 7300 (4200) 5269.0 (5280.11 5279.0 (5281.9) 210 (800)
30 1135+15 730U 5274.2 (5281.9) 5280.4 2504
31 (49+60) (4200) (5281.9) (5284.3) (890)
28th Street 32 1136+65 (50+95) 8000 (3500) 5274.4 (5282.4) 5284.9 (5285.4) 760 (1230)
33 1141+00 (54+75) 8000 (3500) 5278.1 (5286.2) 5286.9 (5288.7) 1090 (1370) FLOODWAI DATA WILL BE PURL HED AT
b Hilton Harvest Hous 33.1 1141+70 (57+65) 8250 (3500) 5278.6 (5288.2) 5287.6 (5290.6) 1060 (1280) A LATER DATE. CON ACT=URBA
Footbridge
34 1146+90 (60+45) 8250 (3500) 5281.9 (5293.7) 5291.9 (5294.6) 1005 (1190) DRAINAGE 8 FLOOD ONTROL STRI
i' 35 1149+55 8250 5284.4 (5295.7) 5293.8 490 OR CITY OF BOULDER FOR DE ILS.
37 1150+10 11,750 5285.0 5299.1 8604
38 1154+70 11,900 5289.0 5300.7 1774
Folsom Field Bridge 39 1157+90 11,900 5291.3 5305.1 1200 t
Stadium Footbridge 40 1159+95 11,900 5292.5 5306.4 12404
41 1165+50 11,900 5299.3 5310.1 5504
19th St.Pootbridge 42 1169+95 11,900 5301.5 5313.3 990
43 1173+55 11,950 5305.0 5316.9 9304
17th Street 45 1177+00 11,950 5310.6 5325.0 1860
High School Foot- 47 1184+80 12,000 5315.0 5330.5 1570
bridge 48 1189+10 12,000 5319.9 5333.6 1320
Arapahoe Ave. 50 1194+50 12,000 5325.5 5340.6 1100
51.2 1197+70 12,000 5330.0 5342.6 820
52 1198+10 12,000 5334.1 5343.5 890
1. Distance in feet above mouth.
2. From center of cbannel looking dovnsireaa.
3. ( ) values related to Arapahoe Avenue over£low.
4. Shallow flooding area not included.
MULLER ENGINEERING COMPANY,INC. UmAN DRAMW• FLOOD eaNlRat amecr TABLE
CONSTILTTNC VKX`IIFRS FLOODPLAIN AND FLOODWAY REFERENCE DATA �� H�pgp AREA DELINEATION ][
741D VANCE Sr.,SM=
LAKEWOOD,COLORADO`m' BOULDER CREEK CITY OF BOULDER CONT.
13m)73243tl
Page 16
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/oLrn<SMOCK FI NI aM. a, GENERAL NOTES
�
lwpw T1PIw91OK rR A 0 LEGEND DK 0M a 0[GIIRS«O L -M "M IMMOISM[m K rIJL[D
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Gw xv E I •••:` +v p.1 yj•m t URMD TML F DVIM DI ml,CfWSWr RSIWL!E ,/Y nI1CA M1D SIMLL
SIDEWALK �L Crw lK RAD[I Ca M f r Cum A m R
"4 `� TRANSIfgN m K WtT wKl+m LL LVLT
'v�� Gil""(ITrt 2) WII[A(rrr[Z) ®—aTl[I OlOSS YOFK TI1,L4 K,/r/rT.104"DwL1L1C wv iIDY mvill Ab
R NOT ICDUIm 6 KGWRFD /rt.I DRA<wC rOwARD CIM.
SIDEWALK + DAf AFF/I Lwtl K IDLWm wa,plMCKly ATIM COIL Ab RIGFU O,bE(I GIK Alq DRRK 9uLl K LOG,tD AT M RA LK.
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CONSTRUCTION OF CONCRETE MA o w 2"Ab W. r-r. TI•r 91Au K A RXD T/2 AMD ,/x
CURB CUT FOR DRIVEWAYS GUTTERS AT INTERSECTION Lam^ N O M artLR.
"/}•ew,
C « C 1 / C w C
r
L Lx
CURB AND GUTTER TYPE 2 CURB AND GUTTER TYPE 2 CURB AND GUTTER TYPE 2 CURB AND GUTTER TYPE 2 CURB AND GUTTER TYPE 2
(SECTION E B) (SECTION I M) (SECTION It B) (SECTION RM) (SECTION MS)
(6- BARRIER - I- GUTTER) (6- MOUNTABLE - T' GOITER) (6- BARRIER - 2' GUTTER) . (6- MOUNTABLE - 2- GUTTER) (4- MOUNTABLE WON SIDEWALK)
i I GII,[R�—r AM SOEIF,L<(ILL FLAM]�
WAJ•R -� rK"m Yr" fwpJdwf wtDwl Fw LK CWL iRw91Cw I SO[wYN,KMRfICw 1
A A r y r ANL mR l,I A1Q�' _ �•---vwMK[K>Q RAM aA^•t RORrE ML •
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'. 1 '• '• •' . .' .. . .:. A' � a.YAR.ww. pY.,' .wA<. - ••• DRIVEWAY ..
nAz ADwr aauwtD KItI[LLAGTw a - - .
zW EIIG[l0S m rELr. ffF SW A«R sIWL K RI®
OML a QRIG AA mOlm IL R[oLlRm rwFN «M SDErY<.l MEAVKz ar r t n�K WK yM lY�v ML K wLASUR�W
TRANSVERSE CONTRACTION .•D1c Kw. �MAIELrIOI1 11W'AIL� br woK raw aa0 rt. Or o[r w we %=[)"A o "V Awa AwD Fb roR As-mwo1ET[
JOINT FOR CONCRETE SIDEWALK aA05Yw«w r D KGT Dw «M a«s cu .al FA LitKr
K vrww•m No Fb
PAVEMENT (DRIVEWAYS) CONCRETE SIDEWALK EXPANSION JOINT GUTTER ME 2 ra,K qrL A<D army
- L— m K Fp/1m wanLmrwL.
CONCRETE PAVEMENT (DRIVEWAYS)
r ,k" C L— rL`1 SECTION A—A
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DEPARTMENT OF TRANSPORTATION
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ir:/<Ir DLrwwm ALAspc«c sols Ar L root yACNG Lw5 Fr[wtYr Ar CURBS AND GUTTERS
: m K GlalEo«t/}-/N m«FKSDa mN m. dart T101.aDG
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R1STAl1AFCN R m K«111Dm«M FACT LO iM Cw,L.
CURB TYPE 2 CURB TYPE 2 CURB TYPE 4 CURB TYPE 4 CURB TYPE 6 6sum er STANDARD PLAN NO
(6- BARRIER) (SECTION B) (6" MOUNTABLE) (SECTION M) (6- BARRIER) (SECTION B) (6- MOUNTABLE) (SECTION M) (4- MOUNTABLE) (SECTION M)QTEStAt I)EDGM LLAACN M-609-1DATE'NOV.L T992 SHEET i OF 1
A- i"
' LANDSCAPING SEPARATE CURB. PROVIDE (2) #4
REINFORCING BMS.
CONCRETE PAVING: PORTLAND CEMENT1�2" PREMOLDED FILLER W/
ASTM C150 TYPE I OR 11. BTUMINOUS SEAL AT TOP
DOWEL INTO GRASSCRETE AS REO'D. ASTM C33 SAND W/ 1" TOPSOIL
1/2" PREMOLDED FILLER W/ AND SEED
' BITUMINOUS SEAL AT TOP .) I' w.." 6"O.C. CAST-IN-PLACE CONCRETE BLOCKS
SAND FILTER LAYER
GRAVEL LAYER CDOT CLASS 6
AGGREGATE, FACTURED FACE
' ALL SIDES.
COMPACT EARTH UP
TO 959. RELATIVE COMPACTION.
' SEPARATE CURB. PROVIDE (2) #4
REINFORCING BARS.
1/2" PREMOLDED FILLER W/
B MINOUS SEAL AT TOP PRECAST BUMPER
ASTM C33 SAND W/ DOWELED INTO GRASSCRETE
1" TOPSOIL AND SEED
MODULAR BLOCKS
' SAND FILTER LAYER 6"
b
' O
GRAVEL LAYER CDOT CLASS 6
AGGREGATE, FACTURED FACE
' COMPACT EARTH UP
TO 95% RELATIVE COMPACTION.
ARNAROPA UNIVERSITY 05.23.00
FRC PROJECT TITLE DATE DWG. NO.
' 7 3 0 1 7TH STREET S U T E 4 2 0 DRAWING TITLE SCALE SK_1
D E N V E R C O L O R A D O a 0 2 0 2 GRASSCRETE PAVING DETAILS 1/2"=1'-0"