DRAINAGE REPORT

for

ARACO ENTERPRISES LLC - BUILDING ADDITION 7470 SOUTHMOOR DRIVE, FOUNTAIN, CO

Prepared for:

Araco Enterprises LLC 7470 Southmoor Drive Fountain, CO 80817

October 24, 2019

Prepared by:

19 E. Willamette Ave.

Colorado Springs, CO 80903 (719)-477-9429

www.jpsengr.com

JPS Project No. 111705 PPR-19-___

ARACO ENTERPRISES LLC - BUILDING ADDITION 7470 SOUTHMOOR DRIVE, FOUNTAIN, CO

DRAINAGE REPORT STATEMENTS 1. Engineer’s Statement: The attached drainage plan and report were prepared under my direction and supervision and are correct to the best of my knowledge and belief. Said drainage report has been prepared according to the criteria established by the County for drainage reports and said report is in conformity with the master plan for the drainage basin. I accept responsibility for liability caused by negligent acts, errors or omissions on my part in preparing this report: ______________________________________________ John P. Schwab Colorado P.E. No. 29891 2. Developer’s Statement: I, the developer have read and will comply with all the requirements specified in this drainage report and plan. By: _____________________________________ ____________________ Printed Name: Arturo Acosta Date Title: Manager 3. El Paso County Statement: Filed in accordance with the requirements of the El Paso County Land Development Code, Drainage Criteria Manual, Volumes 1 and 2, and Engineering Criteria Manual as amended. Jennifer Irvine, P.E. Date County Engineer / ECM Administrator Conditions:

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I. INTRODUCTION A. Property Location and Description Araco Enterprises LLC is planning to construct an addition on the east side of their existing contractor’s office building at 7470 Southmoor Drive in Fountain, Colorado. The project site (El Paso County Assessor’s No. 65244-00-085) is an unplatted 4.2-acre developed parcel described as a tract in the Southeast Quarter of Section 24, Township 15 South, Rage 66 West of the 6th P.M. The property is located along the southwest side of Southmoor Drive. The property is zoned M (Industrial). Southmoor Drive is a paved public street adjoining the northeast boundary of the property, and the southwest boundary of the site adjoins the Mesa Ridge Parkway (State Highway 16) right-of-way. The Crews Gulch drainage channel flows westerly across the north end of the site, and the northern boundary of the property adjoins an 11-acre park tract owned by El Paso County. The site development plan consists of proposed 6,000 square-foot building addition on the east side of the existing contractor’s office building, with associated parking and site improvements impacting a total disturbed area of approximately 2-acres. Access will continue to be provided by the existing driveway and parking connections to Southmoor Drive along the northeast boundary of the site. The project will include limited internal parking and driveway improvements consisting primarily of asphalt millings. B. Scope This Drainage Report has been prepared in support of the Site Development Plan submittal for this project, in accordance with El Paso County drainage criteria. This report will provide a summary of site drainage issues impacting the proposed development, including analysis of upstream drainage patterns, site-specific developed drainage patterns, and impacts on downstream facilities. This report is based on the guidelines and criteria presented in the City of Colorado Springs and El Paso County “Drainage Criteria Manual.” II. EXISTING / PROPOSED DRAINAGE CONDITIONS According to the Natural Resources Conservation Services (NRCS) web soil survey, the majority of on-site soils are comprised of “Ellicott loamy coarse sand” and “Schamber-Razor complex,” with a small area comprised of “Manzanola silty clay loam” soils along the southeast corner of the site. The majority of on-site soils are classified as hydrologic soils group A. The existing site topography slopes downward to the southwest with grades of approximately 1-3 percent.

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Existing Conditions The existing drainage patterns are depicted on the enclosed Historic Drainage Plan (Figure EX1, Appendix D). The majority of the site has been delineated as Basin A, which sheet flows southwesterly across the property towards an existing stormwater detention basin within the Mesa Ridge Parkway right-of-way. The existing detention basin appears to have been constructed to mitigate developed drainage impacts from a previous CDOT highway improvement project. Basin A sheet flows southwesterly to Design Point #1, with historic peak flows calculated as Q5 = 3.1 cfs and Q100 = 6.0 cfs. Basin B has been delineated as the small area at the north end of the property which sheet flows into the Crews Gulch drainage channel, flowing westerly across the property. Drainage from Basin B flows to Design Point #2, with historic peak flows calculated as Q5 = 0.2 cfs and Q100 = 1.2 cfs. Proposed Conditions As shown on the enclosed Developed Drainage Plan (Figure D1, Appendix D), the developed area of the site has been delineated as two on-site drainage basins (A1-A2). Developed flows have been calculated based on the impervious areas associated with the existing and proposed development. The gravel parking and storage area within the fence towards the north end of the site has been delineated as developed Basin A1, which sheet flows northwesterly to the proposed private Storm Inlet A1 (Type 16) in the northwest corner of the parking area. Developed peak flows at Design Point #A1 are calculated as Q5 = 1.5 cfs and Q100 = 3.0 cfs. Private Storm Sewer A1 (15” HDPE) will convey the flow from Inlet A1 southeasterly to daylight in the curb flowing into the Parking Lot Detention Basin at Inlet A2. The balance of the developed site has been delineated as Basin A2, which sheet flows southwesterly to private Inlet A2 (Type 13) within the Parking Lot Detention Basin. The proposed building addition will be graded with protective slopes to provide positive drainage away from the building. Curb and gutter concrete crosspans and drainage swales within the on-site parking and driveway areas will convey developed flows to the new Parking Lot Detention Basin within the existing low area along the southwest property boundary. Developed peak flows at Design Point #A2 are calculated as Q5 = 3.8 cfs and Q100 = 7.3 cfs. Developed flows from Basins A1 and A2 combine at Design Point #1, with peak flows calculated as Q5 = 4.6 cfs and Q100 = 8.9 cfs. Recognizing that current County drainage criteria require stormwater detention and permanent stormwater quality best management practices for disturbed areas greater than one acre in size, the proposed Parking Lot Detention Basin within Basin A2 has been designed to mitigate developed drainage impacts and meet the current County stormwater requirements.

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Basin B at the north end of the site will remain undisturbed, and will continue to sheet flows into the Crews Gulch drainage channel. Developed peak flows at Design Point #2 are calculated as Q5 = 0.2 cfs and Q100 = 1.2 cfs, matching existing conditions. Hydrologic calculations for the parcel are detailed in the attached spreadsheet tables (Appendix A), and peak flows are identified on Figures EX1 and D1. The contractor will need to implement standard best management practices for erosion control during construction. III. DRAINAGE PLANNING FOUR STEP PROCESS El Paso County Drainage Criteria require drainage planning to include a Four Step Process for receiving water protection that focuses on reducing runoff volumes, treating the water quality capture volume (WQCV), stabilizing drainageways, and implementing long-term source controls. As stated in DCM Volume 2, the Four Step Process is applicable to all new and re-development projects with construction activities that disturb 1 acre or greater or that disturb less than 1 acre but are part of a larger common plan of development. The Four Step Process has been implemented as follows in the planning of this project: Step 1: Employ Runoff Reduction Practices

The proposed internal site paving improvements will utilize asphalt millings to minimize new impervious areas and encourage stormwater infiltration.

Step 2: Stabilize Drainageways

The Crews Gulch channel flowing across the north end of the site has been stabilized with existing riprap bank protection along the bank of the channel within this property.

Routing flows through the on-site Detention Basin will minimize impacts to existing downstream drainageways.

Step 3: Provide Water Quality Capture Volume (WQCV)

Site drainage from the building addition area and developed parts of the site will be routed through a proposed Extended Detention Basin (EDB), which will capture and slowly release the WQCV over a 40-hour design release period.

Step 4: Consider Need for Industrial and Commercial BMPs On-site drainage will be routed through the private Extended Detention Basin

(EDB) to minimize introduction of contaminants to the downstream public drainage system.

The Owner will be responsible to implement and maintain a stormwater management plan (SWMP), which will include proper housekeeping practices for this commercial property.

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IV. STORMWATER DETENTION & WATER QUALITY The proposed drainage and grading plan for this site includes a private Extended Detention Basin (EDB) within the driveway and parking area along the southwest boundary of the property. The proposed EDB will provide the required stormwater detention and water quality mitigation for the site in accordance with current El Paso County drainage criteria. Based on the net impervious area calculations in Appendix C, the required 100-year Detention Volume, which includes the Water Quality Capture Volume (WQCV), is 0.08 acre-feet, and the proposed EDB provides a design volume of 0.12 acre-feet. The Detention Basin outlet structure will provide an outlet orifice and spillway discharging to the southwest property boundary. The proposed stormwater detention facilities will be privately owned and maintained by the property owner, and maintenance access is readily available from the driveway and parking area. V. FLOODPLAIN IMPACTS The northwest part of the site is impacted by FEMA 100-year floodplain boundaries along the Crews Gulch channel according to the FEMA floodplain map for this area, FIRM Panel No. 08041C0951G dated December 7, 2018 (see Appendix D). The proposed Building Addition is located beyond 100-year floodplain limits. VI. DRAINAGE BASIN FEES This site is located within the Crews Gulch Drainage Basin. No public drainage improvements are required for development of this site. No subdivision platting is proposed at this time, and there are no applicable drainage fees required with the Site Development Plan. VII. SUMMARY The developed drainage patterns associated with the proposed Araco Enterprises Building Addition project will remain consistent with historic conditions. The proposed Extended Detention Basin within the parking and driveway area along the southwest boundary of the site will provide stormwater detention and water quality mitigation as required for the new site improvements. Proper construction and maintenance of the proposed on-site drainage facilities, in conjunction with proper erosion control practices, will ensure that this developed site has no significant adverse drainage impact on downstream or surrounding areas.

APPENDIX A

HYDROLOGIC CALCULATIONS

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Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

28 Ellicott loamy coarse sand, 0 to 5 percent slopes

A 3.8 57.1%

82 Schamber-Razor complex, 8 to 50 percent slopes

A 2.2 32.5%

MzA Manzanola silty clay loam, saline, 0 to 2 percent slopes

C 0.7 10.4%

Totals for Area of Interest 6.7 100.0%

Hydrologic Soil Group—El Paso County Area, Colorado Araco Concrete

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

6/23/2019Page 3 of 4

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—El Paso County Area, Colorado Araco Concrete

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

6/23/2019Page 4 of 4

Chapter 6 Hydrology

May 2014 City of Colorado Springs 6-17Drainage Criteria Manual, Volume 1

Table 6-6. Runoff Coefficients for Rational Method(Source: UDFCD 2001)

3.2 Time of Concentration

One of the basic assumptions underlying the Rational Method is that runoff is a function of the averagerainfall rate during the time required for water to flow from the hydraulically most remote part of thedrainage area under consideration to the design point. However, in practice, the time of concentration canbe an empirical value that results in reasonable and acceptable peak flow calculations.

For urban areas, the time of concentration (tc) consists of an initial time or overland flow time (ti) plus thetravel time (tt) in the storm sewer, paved gutter, roadside drainage ditch, or drainage channel. For non-urban areas, the time of concentration consists of an overland flow time (ti) plus the time of travel in aconcentrated form, such as a swale or drainageway. The travel portion (tt) of the time of concentrationcan be estimated from the hydraulic properties of the storm sewer, gutter, swale, ditch, or drainageway.Initial time, on the other hand, will vary with surface slope, depression storage, surface cover, antecedentrainfall, and infiltration capacity of the soil, as well as distance of surface flow. The time of concentrationis represented by Equation 6-7 for both urban and non-urban areas.

HSG A&B HSG C&D HSG A&B HSG C&D HSG A&B HSG C&D HSG A&B HSG C&D HSG A&B HSG C&D HSG A&B HSG C&DBusiness Commercial Areas 95 0.79 0.80 0.81 0.82 0.83 0.84 0.85 0.87 0.87 0.88 0.88 0.89 Neighborhood Areas 70 0.45 0.49 0.49 0.53 0.53 0.57 0.58 0.62 0.60 0.65 0.62 0.68

Residential 1/8 Acre or less 65 0.41 0.45 0.45 0.49 0.49 0.54 0.54 0.59 0.57 0.62 0.59 0.65 1/4 Acre 40 0.23 0.28 0.30 0.35 0.36 0.42 0.42 0.50 0.46 0.54 0.50 0.58 1/3 Acre 30 0.18 0.22 0.25 0.30 0.32 0.38 0.39 0.47 0.43 0.52 0.47 0.57 1/2 Acre 25 0.15 0.20 0.22 0.28 0.30 0.36 0.37 0.46 0.41 0.51 0.46 0.56 1 Acre 20 0.12 0.17 0.20 0.26 0.27 0.34 0.35 0.44 0.40 0.50 0.44 0.55

Industrial Light Areas 80 0.57 0.60 0.59 0.63 0.63 0.66 0.66 0.70 0.68 0.72 0.70 0.74 Heavy Areas 90 0.71 0.73 0.73 0.75 0.75 0.77 0.78 0.80 0.80 0.82 0.81 0.83

Parks and Cemeteries 7 0.05 0.09 0.12 0.19 0.20 0.29 0.30 0.40 0.34 0.46 0.39 0.52Playgrounds 13 0.07 0.13 0.16 0.23 0.24 0.31 0.32 0.42 0.37 0.48 0.41 0.54Railroad Yard Areas 40 0.23 0.28 0.30 0.35 0.36 0.42 0.42 0.50 0.46 0.54 0.50 0.58

Undeveloped Areas Historic Flow Analysis-- Greenbelts, Agriculture

20.03 0.05 0.09 0.16 0.17 0.26 0.26 0.38 0.31 0.45 0.36 0.51

Pasture/Meadow 0 0.02 0.04 0.08 0.15 0.15 0.25 0.25 0.37 0.30 0.44 0.35 0.50 Forest 0 0.02 0.04 0.08 0.15 0.15 0.25 0.25 0.37 0.30 0.44 0.35 0.50 Exposed Rock 100 0.89 0.89 0.90 0.90 0.92 0.92 0.94 0.94 0.95 0.95 0.96 0.96 Offsite Flow Analysis (when landuse is undefined)

450.26 0.31 0.32 0.37 0.38 0.44 0.44 0.51 0.48 0.55 0.51 0.59

Streets Paved 100 0.89 0.89 0.90 0.90 0.92 0.92 0.94 0.94 0.95 0.95 0.96 0.96 Gravel 80 0.57 0.60 0.59 0.63 0.63 0.66 0.66 0.70 0.68 0.72 0.70 0.74

Drive and Walks 100 0.89 0.89 0.90 0.90 0.92 0.92 0.94 0.94 0.95 0.95 0.96 0.96Roofs 90 0.71 0.73 0.73 0.75 0.75 0.77 0.78 0.80 0.80 0.82 0.81 0.83Lawns 0 0.02 0.04 0.08 0.15 0.15 0.25 0.25 0.37 0.30 0.44 0.35 0.50

Land Use or SurfaceCharacteristics

PercentImpervious

Runoff Coefficients

2-year 5-year 10-year 25-year 50-year 100-year

Hydrology Chapter 6

6-18 City of Colorado Springs May 2014Drainage Criteria Manual, Volume 1

tic ttt (Eq. 6-7)

Where:

tc = time of concentration (min)

ti = overland (initial) flow time (min)

tt = travel time in the ditch, channel, gutter, storm sewer, etc. (min)

3.2.1 Overland (Initial) Flow Time

The overland flow time, ti, may be calculated using Equation 6-8.

33.05

i (Eq. 6-8)

Where:

ti = overland (initial) flow time (min)C5 = runoff coefficient for 5-year frequency (see Table 6-6)L = length of overland flow (300 ft maximum for non-urban land uses, 100 ft maximum for

urban land uses)S = average basin slope (ft/ft)

Note that in some urban watersheds, the overland flow time may be very small because flows quicklyconcentrate and channelize.

3.2.2 Travel Time

For catchments with overland and channelized flow, the time of concentration needs to be considered incombination with the travel time, tt, which is calculated using the hydraulic properties of the swale, ditch,or channel. For preliminary work, the overland travel time, tt, can be estimated with the help of Figure 6-25 or Equation 6-9 (Guo 1999).

5.0wv (Eq. 6-9)

Where:

V = velocity (ft/s)

Cv = conveyance coefficient (from Table 6-7)

Sw = watercourse slope (ft/ft)

Chapter 6 Hydrology

May 2014 City of Colorado Springs 6-19Drainage Criteria Manual, Volume 1

Table 6-7. Conveyance Coefficient, Cv

Type of Land Surface Cv

Heavy meadow 2.5

Tillage/field 5

Riprap (not buried)* 6.5

Short pasture and lawns 7

Nearly bare ground 10

Grassed waterway 15

Paved areas and shallow paved swales 20* For buried riprap, select Cv value based on type of vegetative cover.

The travel time is calculated by dividing the flow distance (in feet) by the velocity calculated usingEquation 6-9 and converting units to minutes.

The time of concentration (tc) is then the sum of the overland flow time (ti) and the travel time (tt) perEquation 6-7.

3.2.3 First Design Point Time of Concentration in Urban Catchments

Using this procedure, the time of concentration at the first design point (typically the first inlet in thesystem) in an urbanized catchment should not exceed the time of concentration calculated using Equation6-10. The first design point is defined as the point where runoff first enters the storm sewer system.

(Eq. 6-10)

Where:

tc = maximum time of concentration at the first design point in an urban watershed (min)

L = waterway length (ft)

Equation 6-10 was developed using the rainfall-runoff data collected in the Denver region and, in essence,the Rational Method. Normally, Equation 6-10 will result in a lesser

time of concentration at the first design point and will govern in an urbanized watershed. For subsequentdesign points, the time of concentration is calculated by accumulating the travel times in downstreamdrainageway reaches.

3.2.4 Minimum Time of Concentration

If the calculations result in a tc of less than 10 minutes for undeveloped conditions, it is recommended thata minimum value of 10 minutes be used. The minimum tc for urbanized areas is 5 minutes.

3.2.5 Post-Development Time of Concentration

As Equation 6-8 indicates, the time of concentration is a function of the 5-year runoff coefficient for adrainage basin. Typically, higher levels of imperviousness (higher 5-year runoff coefficients) correspondto shorter times of concentration, and lower levels of imperviousness correspond to longer times of

Hydrology Chapter 6

6-52 City of Colorado Springs May 2014Drainage Criteria Manual, Volume 1

Figure 6-5. Colorado Springs Rainfall Intensity Duration Frequency

IDF Equations

I100 = -2.52 ln(D) + 12.735

I50 = -2.25 ln(D) + 11.375

I25 = -2.00 ln(D) + 10.111

I10 = -1.75 ln(D) + 8.847

I5 = -1.50 ln(D) + 7.583

I2 = -1.19 ln(D) + 6.035

Note: Values calculated byequations may not preciselyduplicate values read from figure.

JPS

EN

GIN

EE

RIN

G

AR

AC

O C

ON

CR

ET

EC

OM

PO

SIT

E R

UN

OF

F C

OE

FF

ICIE

NT

S

HIS

TO

RIC

CO

ND

ITIO

NS

5-Y

EA

R C

VA

LU

ES

TO

TA

L

SU

B-A

RE

A 1

SU

B-A

RE

A 2

SU

B-A

RE

A 3

AR

EA

D

EV

ELO

PM

EN

T/

AR

EA

DE

VE

LOP

ME

NT

/

DE

VE

LOP

ME

NT

/W

EIG

HT

ED

BA

SIN

(AC

)(A

C)

CO

VE

RC

(AC

)C

OV

ER

C(A

C)

CO

VE

RC

C V

ALU

E

A3.

760.

29B

UIL

DIN

G /

PA

VE

ME

NT

0.9

1.48

GR

AV

EL

0.59

1.99

LAN

DS

CA

PE

D0.

080.

302

100-

YE

AR

C V

AL

UE

S TO

TA

L

SU

B-A

RE

A 1

SU

B-A

RE

A 2

SU

B-A

RE

A 3

AR

EA

D

EV

ELO

PM

EN

T/

AR

EA

DE

VE

LOP

ME

NT

/

DE

VE

LOP

ME

NT

/W

EIG

HT

ED

BA

SIN

(AC

)(A

C)

CO

VE

RC

(AC

)C

OV

ER

C(A

C)

CO

VE

RC

C V

ALU

E

A3.

760.

29B

UIL

DIN

G /

PA

VE

ME

NT

0.96

1.48

GR

AV

EL

0.7

1.99

LAN

DS

CA

PE

D0.

350.

350

DE

VE

LO

PE

D C

ON

DIT

ION

S

5-Y

EA

R C

VA

LU

ES

TO

TA

L

SU

B-A

RE

A 1

SU

B-A

RE

A 2

SU

B-A

RE

A 3

AR

EA

D

EV

ELO

PM

EN

T/

AR

EA

DE

VE

LOP

ME

NT

/

DE

VE

LOP

ME

NT

/W

EIG

HT

ED

BA

SIN

(AC

)(A

C)

CO

VE

RC

(AC

)C

OV

ER

C(A

C)

CO

VE

RC

C V

ALU

E

A3.

760.

428

BU

ILD

ING

/ P

AV

EM

EN

T0.

91.

625

GR

AV

EL

0.59

1.71

LAN

DS

CA

PE

D0.

080.

357

100-

YE

AR

C V

AL

UE

S TO

TA

L

SU

B-A

RE

A 1

SU

B-A

RE

A 2

SU

B-A

RE

A 3

AR

EA

D

EV

ELO

PM

EN

T/

AR

EA

DE

VE

LOP

ME

NT

/

DE

VE

LOP

ME

NT

/W

EIG

HT

ED

BA

SIN

(AC

)(A

C)

CO

VE

RC

(AC

)C

OV

ER

C(A

C)

CO

VE

RC

C V

ALU

E

A3.

760.

428

BU

ILD

ING

/ P

AV

EM

EN

T0.

961.

625

GR

AV

EL

0.7

1.71

LAN

DS

CA

PE

D0.

350.

412

RA

TL.

AR

AC

O10

/23/

2019

JPS

EN

GIN

EE

RIN

G

AR

AC

O C

ON

CR

ET

E

R

AT

ION

AL

ME

TH

OD

HIS

TO

RIC

FL

OW

S

CH

AN

NE

LC

ON

VE

YA

NC

ES

CS

(2)

T

OT

AL

TO

TA

L

IN

TE

NS

ITY

(5)

P

EA

K F

LO

W

BA

SIN

DE

SIG

NA

RE

A5-

YE

AR

100-

YE

AR

LE

NG

TH

SL

OP

ET

co (

1)L

EN

GT

HC

OE

FF

ICIE

NT

SL

OP

EV

EL

OC

ITY

Tt (

3)T

c (4)

Tc (

4)5-

YR

100-

YR

Q5 (

6)Q

100 (

6)

PO

INT

(AC

)(F

T)

(FT

/FT

)(M

IN)

(FT

)C

(FT

/FT

)(F

T/S

)(M

IN)

(MIN

)(M

IN)

(IN

/HR

)(I

N/H

R)

(CF

S)

(CF

S)

A

13.

760.

302

0.35

030

00.

0125

.370

150.

014

1.77

0.7

26.0

26.0

2.70

4.53

3.06

5.96

B2

0.44

0.08

00.

350

600.

175.

713

015

0.01

51.

841.

26.

86.

84.

707.

890.

171.

21

DE

VE

LO

PE

D F

LO

WS

CH

AN

NE

LC

ON

VE

YA

NC

ES

CS

(2)

T

OT

AL

TO

TA

L

IN

TE

NS

ITY

(5)

P

EA

K F

LO

W

BA

SIN

DE

SIG

NA

RE

A5-

YE

AR

100-

YE

AR

LE

NG

TH

SL

OP

ET

co (

1)L

EN

GT

HC

OE

FF

ICIE

NT

SL

OP

EV

EL

OC

ITY

Tt (

3)T

c (4)

Tc (

4)5-

YR

100-

YR

Q5 (

6)Q

100 (

6)

PO

INT

(AC

)(F

T)

(FT

/FT

)(M

IN)

(FT

)C

(FT

/FT

)(F

T/S

)(M

IN)

(MIN

)(M

IN)

(IN

/HR

)(I

N/H

R)

(CF

S)

(CF

S)

A

1A

11.

070.

357

0.41

250

0.01

9.6

130

200.

012.

001.

110

.710

.74.

036.

761.

542.

98A

2A

22.

690.

357

0.41

250

0.02

7.6

490

200.

011

2.10

3.9

11.5

11.5

3.92

6.57

3.76

7.29

Pip

e A

1

440

200.

005

1.41

5.2

A1,

A2

13.

760.

357

0.41

2

15

.915

.93.

435.

774.

618.

93

B2

0.44

0.08

00.

350

600.

175.

713

015

0.01

51.

841.

26.

86.

84.

707.

890.

171.

21

1) O

VE

RLA

ND

FLO

W T

co =

(0.

395*

(1.1

-RU

NO

FF

CO

EF

FIC

IEN

T)*

(OV

ER

LAN

D F

LOW

LE

NG

TH

^(0.

5)/(

SLO

PE

^(0.

333)

)2)

SC

S V

ELO

CIT

Y =

C *

((S

LOP

E(F

T/F

T)^

0.5)

C =

2.5

FO

R H

EA

VY

ME

AD

OW

C =

5 F

OR

TIL

LAG

E/F

IELD

C =

7 F

OR

SH

OR

T P

AS

TU

RE

AN

D L

AW

NS

C =

10

FO

R N

EA

RLY

BA

RE

GR

OU

ND

C =

15

FO

R G

RA

SS

ED

WA

TE

RW

AY

C =

20

FO

R P

AV

ED

AR

EA

S A

ND

SH

ALL

OW

PA

VE

D S

WA

LES

3) M

AN

NIN

G'S

CH

AN

NE

L T

RA

VE

L T

IME

= L

/V (

WH

EN

CH

AN

NE

L V

ELO

CIT

Y IS

KN

OW

N)

4) T

c =

Tco

+ T

t**

* IF

TO

TA

L T

IME

OF

CO

NC

EN

TR

AT

ION

IS L

ES

S T

HA

N 5

MIN

UT

ES

, TH

EN

5 M

INU

TE

S IS

US

ED

5) I

NT

EN

SIT

Y B

AS

ED

ON

I-D

-F E

QU

AT

ION

S IN

CIT

Y O

F C

OLO

RA

DO

SP

RIN

GS

DR

AIN

AG

E C

RIT

ER

IA M

AN

UA

L

I 5 =

-1.

5 *

ln(T

c) +

7.5

83

I 1

00 =

-2.

52 *

ln(T

c) +

12.

735

6) Q

= C

iA

Ove

rlan

d F

low

Ch

ann

el f

low

C

Ove

rlan

d F

low

Ch

ann

el f

low

C

RA

TL.

AR

AC

O10

/23/

2019

APPENDIX B

HYDRAULIC CALCULATIONS

JPS

EN

GIN

EE

RIN

G

AR

AC

O C

ON

CR

ET

E -

74

70 S

OU

TH

MO

OR

DR

IVE

ST

OR

M IN

LE

T S

IZIN

G S

UM

MA

RY

B

AS

IN F

LOW

INLE

T F

LOW

Q5

Q10

0IN

LET

Q5

Q10

0IN

LET

IN

LET

FLO

WF

LOW

FLO

W %

FLO

WF

LO

WC

ON

DIT

ION

/IN

LET

CA

PA

CIT

YIN

LET

DP

(CF

S)

(CF

S)

OF

BA

SIN

(CF

S)

(CF

S)

TY

PE

SIZ

E(C

FS

)

A

1A

11.

53.

010

01.

53.

0S

UM

P T

YP

E 1

6S

ING

LE5.

6

A2

A2

3.8

7.3

100

3.8

7.3

SU

MP

TY

PE

13

DO

UB

LE8.

8

ST

OR

M-I

NLE

T-S

IZIN

G-A

RA

CO

10/2

3/20

19

Project:Inlet ID:

Gutter Geometry (Enter data in the blue cells)

Maximum Allowable Width for Spread Behind Curb TBACK = 4.0 ft

Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.020 ft/ft

Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.020

Height of Curb at Gutter Flow Line HCURB = 6.00 inches

Distance from Curb Face to Street Crown TCROWN = 50.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.010 ft/ft

Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft

Street Longitudinal Slope - Enter 0 for sump condition SO = 0.000 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm

Max. Allowable Spread for Minor & Major Storm TMAX = 50.0 50.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches

Check boxes are not applicable in SUMP conditions

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = SUMP SUMP cfs

Version 4.05 Released March 2017

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)

(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)Araco Enterprises - Inlet A1 (Sump Condition)

Inlet A1

UD-Inlet_v4.05-Araco-A1, Inlet A1 10/23/2019, 1:24 PM

Design Information (Input) MINOR MAJOR

Type of Inlet Type =

Local Depression (additional to continuous gutter depression 'a' from above) alocal = 2.00 2.00 inches

Number of Unit Inlets (Grate or Curb Opening) No = 1 1

Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 7.8 inches

Grate Information MINOR MAJOR

Length of a Unit Grate Lo (G) = 3.00 3.00 feet

Width of a Unit Grate Wo = 1.73 1.73 feet

Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.31 0.31

Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50

Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.60 3.60

Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60

Curb Opening Information MINOR MAJOR

Length of a Unit Curb Opening Lo (C) = 3.00 3.00 feet

Height of Vertical Curb Opening in Inches Hvert = 6.50 6.50 inches

Height of Curb Orifice Throat in Inches Hthroat = 5.25 5.25 inches

Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees

Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feet

Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10

Curb Opening Weir Coefficient (typical value 2.3-3.7) Cw (C) = 3.70 3.70

Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66

Low Head Performance Reduction (Calculated) MINOR MAJOR

Depth for Grate Midwidth dGrate = 0.523 0.669 ft

Depth for Curb Opening Weir Equation dCurb = 0.33 0.48 ft

Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00

Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00

Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00

MINOR MAJOR

Total Inlet Interception Capacity (assumes clogged condition) Qa = 3.9 5.6 cfsInlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 1.5 3.0 cfs

Denver No. 16 Combination

INLET IN A SUMP OR SAG LOCATIONVersion 4.05 Released March 2017

H-VertH -Curb

W

Lo (C )

Lo (G)

W o

WP

Denver No. 16 Combination

Override Depths

UD-Inlet_v4.05-Araco-A1, Inlet A1 10/23/2019, 1:24 PM

Project:Inlet ID:

Gutter Geometry (Enter data in the blue cells)

Maximum Allowable Width for Spread Behind Curb TBACK = 6.0 ft

Side Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.020 ft/ft

Manning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.020

Height of Curb at Gutter Flow Line HCURB = 18.00 inches

Distance from Curb Face to Street Crown TCROWN = 30.0 ft

Gutter Width W = 2.00 ft

Street Transverse Slope SX = 0.020 ft/ft

Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft

Street Longitudinal Slope - Enter 0 for sump condition SO = 0.000 ft/ft

Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016

Minor Storm Major Storm

Max. Allowable Spread for Minor & Major Storm TMAX = 30.0 30.0 ft

Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 12.0 inches

Check boxes are not applicable in SUMP conditions

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm

MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = SUMP SUMP cfs

Version 4.05 Released March 2017

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)

(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)Araco Enterprises - Inlet A2 (Sump Condition)

Inlet A2

UD-Inlet_v4.05-Araco-A2, Inlet A2 10/23/2019, 1:29 PM

Design Information (Input) MINOR MAJOR

Type of Inlet Type =

Local Depression (additional to continuous gutter depression 'a' from above) alocal = 2.00 2.00 inches

Number of Unit Inlets (Grate or Curb Opening) No = 2 2

Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 8.7 inches

Grate Information MINOR MAJOR

Length of a Unit Grate Lo (G) = 3.00 3.00 feet

Width of a Unit Grate Wo = 1.73 1.73 feet

Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.43 0.43

Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50

Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.30 3.30

Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60

Curb Opening Information MINOR MAJOR

Length of a Unit Curb Opening Lo (C) = N/A N/A feet

Height of Vertical Curb Opening in Inches Hvert = N/A N/A inches

Height of Curb Orifice Throat in Inches Hthroat = N/A N/A inches

Angle of Throat (see USDCM Figure ST-5) Theta = N/A N/A degrees

Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = N/A N/A feet

Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = N/A N/A

Curb Opening Weir Coefficient (typical value 2.3-3.7) Cw (C) = N/A N/A

Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = N/A N/A

Low Head Performance Reduction (Calculated) MINOR MAJOR

Depth for Grate Midwidth dGrate = 0.523 0.749 ft

Depth for Curb Opening Weir Equation dCurb = N/A N/A ft

Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = N/A N/A

Curb Opening Performance Reduction Factor for Long Inlets RFCurb = N/A N/A

Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.71 1.00

MINOR MAJOR

Total Inlet Interception Capacity (assumes clogged condition) Qa = 3.6 8.8 cfsWARNING: Inlet Capacity less than Q Peak for Minor Storm Q PEAK REQUIRED = 3.8 7.3 cfs

CDOT/Denver 13 Valley Grate

INLET IN A SUMP OR SAG LOCATIONVersion 4.05 Released March 2017

H-VertH -Curb

W

Lo (C )

Lo (G)

W o

WP

CDOT/Denver 13 Valley Grate

Override Depths

UD-Inlet_v4.05-Araco-A2, Inlet A2 10/23/2019, 1:29 PM

JPS

EN

GIN

EE

RIN

G

AR

AC

O C

ON

CR

ET

E -

747

0 S

OU

TH

MO

OR

DR

IVE

ST

OR

M S

EW

ER

SIZ

ING

SU

MM

AR

Y

PIP

E F

LOW

P

IPE

CA

PA

CIT

Y

Q

5Q

100

M

IN.

FU

LL P

IPE

FLO

WF

LOW

PIP

EP

IPE

CA

PA

CIT

YP

IPE

BA

SIN

S(C

FS

)(C

FS

)S

IZE

(IN

)S

LOP

E(C

FS

)

A1

A1

1.5

3.0

150.

33%

3.7

A

SS

UM

PT

ION

S:

1.

ST

OR

M D

RA

IN P

IPE

AS

SU

ME

D T

O B

E R

CP

OR

HD

PE

ST

OR

M-I

NLE

T-S

IZIN

G-A

RA

CO

10/2

3/20

19

Hydraulic Analysis Report

Project Data

Project Title: Project - Araco

Designer: JPS

Project Date: Wednesday, October 23, 2019

Project Units: U.S. Customary Units

Notes:

Channel Analysis: SD-A1

Notes:

Input Parameters

Channel Type: Circular

Pipe Diameter: 1.2500 ft

Longitudinal Slope: 0.0033 ft/ft

Manning's n: 0.0130

Depth: 1.2500 ft

Result Parameters

Flow: 3.7109 cfs

Area of Flow: 1.2272 ft^2

Wetted Perimeter: 3.9270 ft

Hydraulic Radius: 0.3125 ft

Average Velocity: 3.0239 ft/s

Top Width: 0.0000 ft

Froude Number: 0.0000

Critical Depth: 0.7782 ft

Critical Velocity: 4.6204 ft/s

Critical Slope: 0.0065 ft/ft

Critical Top Width: 1.21 ft

Calculated Max Shear Stress: 0.2574 lb/ft^2

Calculated Avg Shear Stress: 0.0644 lb/ft^2

APPENDIX C

STORMWATER DETENTION CALCULATIONS

JPS

EN

GIN

EE

RIN

G

AR

AC

O C

ON

CR

ET

EC

OM

PO

SIT

E R

UN

OF

F C

OE

FF

ICIE

NT

S

IMP

ER

VIO

US

AR

EA

S -

EX

IST

ING

CO

ND

ITIO

NS

TO

TA

L

SU

B-A

RE

A 1

SU

B-A

RE

A 2

SU

B-A

RE

A 3

AR

EA

D

EV

ELO

PM

EN

T/

PE

RC

EN

TA

RE

AD

EV

ELO

PM

EN

T/

PE

RC

EN

T

DE

VE

LOP

ME

NT

/P

ER

CE

NT

WE

IGH

TE

DB

AS

IN(A

C)

(AC

)C

OV

ER

IMP

ER

VIO

US

(AC

)C

OV

ER

IMP

ER

VIO

US

(AC

)C

OV

ER

IMP

ER

VIO

US

% IM

P

A4.

200.

29B

UIL

DIN

G /

PA

VE

ME

NT

100

1.48

GR

AV

EL

802.

43LA

ND

SC

AP

ED

035

.095

IMP

ER

VIO

US

AR

EA

S -

DE

VE

LO

PE

D C

ON

DIT

ION

ST

OT

AL

S

UB

-AR

EA

1

S

UB

-AR

EA

2

S

UB

-AR

EA

3

A

RE

A

DE

VE

LOP

ME

NT

/P

ER

CE

NT

AR

EA

DE

VE

LOP

ME

NT

/P

ER

CE

NT

D

EV

ELO

PM

EN

T/

PE

RC

EN

TW

EIG

HT

ED

BA

SIN

(AC

)(A

C)

CO

VE

RIM

PE

RV

IOU

S(A

C)

CO

VE

RIM

PE

RV

IOU

S(A

C)

CO

VE

RIM

PE

RV

IOU

S%

IMP

A4.

200.

428

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Project:

Basin ID:

Depth Increment = ft

Required Volume Calculation Top of Micropool -- 0.00 -- -- -- 10 0.000

Selected BMP Type = EDB EL=5635.5 -- 0.50 -- -- -- 10 0.000 5 0.000

Watershed Area = 4.20 acres -- 1.00 -- -- -- 2,239 0.051 545 0.013

Watershed Length = 570 ft EL=5637.0 -- 2.00 -- -- -- 6,960 0.160 5,097 0.117

Watershed Slope = 0.010 ft/ft -- 3.00 -- -- -- 12,000 0.275 14,647 0.336

Watershed Imperviousness = 6.00% percent -- -- -- --

Percentage Hydrologic Soil Group A = 90.0% percent -- -- -- --

Percentage Hydrologic Soil Group B = 0.0% percent -- -- -- --

Percentage Hydrologic Soil Groups C/D = 10.0% percent -- -- -- --

Desired WQCV Drain Time = 40.0 hours -- -- -- --

Location for 1-hr Rainfall Depths = User Input -- -- -- --

Water Quality Capture Volume (WQCV) = 0.015 acre-feet -- -- -- --

Excess Urban Runoff Volume (EURV) = 0.016 acre-feet -- -- -- --

2-yr Runoff Volume (P1 = 1.19 in.) = 0.011 acre-feet 1.19 inches -- -- -- --

5-yr Runoff Volume (P1 = 1.5 in.) = 0.018 acre-feet 1.50 inches -- -- -- --

10-yr Runoff Volume (P1 = 1.75 in.) = 0.029 acre-feet 1.75 inches -- -- -- --

25-yr Runoff Volume (P1 = 2 in.) = 0.055 acre-feet 2.00 inches -- -- -- --

50-yr Runoff Volume (P1 = 2.25 in.) = 0.099 acre-feet 2.25 inches -- -- -- --

100-yr Runoff Volume (P1 = 2.52 in.) = 0.192 acre-feet 2.52 inches -- -- -- --

500-yr Runoff Volume (P1 = 3.14 in.) = 0.408 acre-feet 3.14 inches -- -- -- --

Approximate 2-yr Detention Volume = 0.010 acre-feet -- -- -- --

Approximate 5-yr Detention Volume = 0.017 acre-feet -- -- -- --

Approximate 10-yr Detention Volume = 0.023 acre-feet -- -- -- --

Approximate 25-yr Detention Volume = 0.030 acre-feet -- -- -- --

Approximate 50-yr Detention Volume = 0.042 acre-feet -- -- -- --

Approximate 100-yr Detention Volume = 0.078 acre-feet -- -- -- --

-- -- -- --

Stage-Storage Calculation -- -- -- --

Zone 1 Volume (WQCV) = 0.015 acre-feet -- -- -- --

Zone 2 Volume (EURV - Zone 1) = 0.002 acre-feet -- -- -- --

Zone 3 Volume (100-year - Zones 1 & 2) = 0.062 acre-feet -- -- -- --

Total Detention Basin Volume = 0.078 acre-feet -- -- -- --

DETENTION BASIN STAGE-STORAGE TABLE BUILDER

Optional Override

Area (ft^2)Length

(ft)

Optional Override Stage (ft)

Stage(ft)

Stage - StorageDescription

Area (ft^2)

Width (ft)

ARACO CONCRETE

A

UD-Detention, Version 3.07 (February 2017)

Volume (ft^3)

Volume (ac-ft)

Area (acre)

Optional User Override1-hr Precipitation

Example Zone Configuration (Retention Pond)

UD-Detention_v3.07-Araco-1019, Basin 10/22/2019, 9:59 AM

Project:

Basin ID:

Stage (ft) Zone Volume (ac-ft) Outlet Type

Zone 1 (WQCV) 1.04 0.015 Orifice Plate

Zone 2 (EURV) 1.07 0.002 Orifice Plate

Zone 3 (100-year) 1.73 0.062 Circular Orifice

0.078 Total

User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP) Calculated Parameters for UnderdrainUnderdrain Orifice Invert Depth = N/A ft (distance below the filtration media surface) Underdrain Orifice Area = N/A ft2

Underdrain Orifice Diameter = N/A inches Underdrain Orifice Centroid = N/A feet

User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP) Calculated Parameters for PlateInvert of Lowest Orifice = 0.00 ft (relative to basin bottom at Stage = 0 ft) WQ Orifice Area per Row = 8.333E-04 ft2

Depth at top of Zone using Orifice Plate = 1.07 ft (relative to basin bottom at Stage = 0 ft) Elliptical Half-Width = N/A feetOrifice Plate: Orifice Vertical Spacing = N/A inches Elliptical Slot Centroid = N/A feet

Orifice Plate: Orifice Area per Row = 0.12 sq. inches (diameter = 3/8 inch) Elliptical Slot Area = N/A ft2

User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest)

Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row 5 (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional)

Stage of Orifice Centroid (ft) 0.00 0.36 0.72

Orifice Area (sq. inches) 0.12 0.12 0.12

Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional)

Stage of Orifice Centroid (ft)

Orifice Area (sq. inches)

User Input: Vertical Orifice (Circular or Rectangular) Calculated Parameters for Vertical OrificeZone 3 Circular Not Selected Zone 3 Circular Not Selected

Invert of Vertical Orifice = 0.50 N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Area = 0.01 N/A ft2

Depth at top of Zone using Vertical Orifice = 1.73 N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Centroid = 0.06 N/A feetVertical Orifice Diameter = 1.50 N/A inches

User Input: Overflow Weir (Dropbox) and Grate (Flat or Sloped) Calculated Parameters for Overflow WeirNot Selected Not Selected Not Selected Not Selected

Overflow Weir Front Edge Height, Ho = N/A N/A ft (relative to basin bottom at Stage = 0 ft) Height of Grate Upper Edge, Ht = N/A N/A feetOverflow Weir Front Edge Length = N/A N/A feet Over Flow Weir Slope Length = N/A N/A feet

Overflow Weir Slope = N/A N/A H:V (enter zero for flat grate) Grate Open Area / 100-yr Orifice Area = N/A N/A should be > 4Horiz. Length of Weir Sides = N/A N/A feet Overflow Grate Open Area w/o Debris = N/A N/A ft2

Overflow Grate Open Area % = N/A N/A %, grate open area/total area Overflow Grate Open Area w/ Debris = N/A N/A ft2

Debris Clogging % = N/A N/A %

User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice) Calculated Parameters for Outlet Pipe w/ Flow Restriction PlateNot Selected Not Selected Not Selected Not Selected

Depth to Invert of Outlet Pipe = N/A N/A ft (distance below basin bottom at Stage = 0 ft) Outlet Orifice Area = N/A N/A ft2

Circular Orifice Diameter = N/A N/A inches Outlet Orifice Centroid = N/A N/A feetHalf-Central Angle of Restrictor Plate on Pipe = N/A N/A radians

User Input: Emergency Spillway (Rectangular or Trapezoidal) Calculated Parameters for SpillwaySpillway Invert Stage= 2.00 ft (relative to basin bottom at Stage = 0 ft) Spillway Design Flow Depth= 0.13 feet

Spillway Crest Length = 20.00 feet Stage at Top of Freeboard = 3.13 feetSpillway End Slopes = 4.00 H:V Basin Area at Top of Freeboard = 0.28 acres

Freeboard above Max Water Surface = 1.00 feet

Routed Hydrograph ResultsDesign Storm Return Period = WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 YearOne-Hour Rainfall Depth (in) = 0.53 1.07 1.19 1.50 1.75 2.00 2.25 2.52 3.14

Calculated Runoff Volume (acre-ft) = 0.015 0.016 0.011 0.018 0.029 0.055 0.099 0.192 0.408OPTIONAL Override Runoff Volume (acre-ft) =

Inflow Hydrograph Volume (acre-ft) = 0.015 0.016 0.010 0.018 0.029 0.055 0.098 0.191 0.407Predevelopment Unit Peak Flow, q (cfs/acre) = 0.00 0.00 0.00 0.02 0.04 0.09 0.26 0.52 1.08

Predevelopment Peak Q (cfs) = 0.0 0.0 0.0 0.1 0.2 0.4 1.1 2.2 4.5Peak Inflow Q (cfs) = 0.2 0.3 0.2 0.3 0.5 0.9 1.6 3.0 6.3

Peak Outflow Q (cfs) = 0.0 0.0 0.0 0.0 0.1 0.1 0.1 1.4 5.2Ratio Peak Outflow to Predevelopment Q = N/A N/A N/A 0.7 0.3 0.2 0.1 0.6 1.1

Structure Controlling Flow = Vertical Orifice 1 Vertical Orifice 1 Vertical Orifice 1 Vertical Orifice 1 Vertical Orifice 1 Vertical Orifice 1 Vertical Orifice 1 Spillway SpillwayMax Velocity through Grate 1 (fps) = N/A N/A N/A N/A N/A N/A N/A N/A N/AMax Velocity through Grate 2 (fps) = N/A N/A N/A N/A N/A N/A N/A N/A N/A

Time to Drain 97% of Inflow Volume (hours) = 5 6 4 6 8 12 19 23 21Time to Drain 99% of Inflow Volume (hours) = 6 6 5 6 9 13 20 24 24

Maximum Ponding Depth (ft) = 0.94 0.95 0.85 0.99 1.15 1.43 1.77 2.08 2.19Area at Maximum Ponding Depth (acres) = 0.04 0.05 0.04 0.05 0.07 0.10 0.13 0.17 0.18

Maximum Volume Stored (acre-ft) = 0.010 0.011 0.006 0.012 0.022 0.045 0.085 0.130 0.149

Detention Basin Outlet Structure Design

UD-Detention, Version 3.07 (February 2017)ARACO CONCRETE

A

Example Zone Configuration (Retention Pond)

COUNTA for Basin Tab = 1 Ao Dia WQ Plate Type Vert Orifice 1 Vert Orifice 2Count_Underdrain = 0 0.11(diameter = 3/8 inch) 2 2 1

Count_WQPlate = 1 0.14(diameter = 7/16 inch)

Count_VertOrifice1 = 1 0.18(diameter = 1/2 inch) Outlet Plate 1 Outlet Plate 2 Drain Time Message Boolean

Count_VertOrifice2 = 0 0.24(diameter = 9/16 inch) 1 1 5yr, <72hr 0

Count_Weir1 = 0 0.29(diameter = 5/8 inch) >5yr, <120hr 0

Count_Weir2 = 0 0.36(diameter = 11/16 inch) Max Depth Row

Count_OutletPipe1 = 0 0.42(diameter = 3/4 inch) WQCV 94 Watershed Constraint Check

Count_OutletPipe2 = 0 0.50(diameter = 13/16 inch) 2 Year 85 Slope 0.010

COUNTA_2 (Standard FSD Setup)= 0 0.58(diameter = 7/8 inch) EURV 95 Shape 1.78

MaxPondDepth_Error? FALSE 0.67(diameter = 15/16 inch) 5 Year 99

Hidden Parameters & Calculations 0.76 (diameter = 1 inch) 10 Year 115 Spillway Depth

0.86(diameter = 1-1/16 inches) 25 Year 143 0.13

WQ Plate Flow at 100yr depth = 0.02 0.97(diameter = 1-1/8 inches) 50 Year 177

CLOG #1= #VALUE! 1.08(diameter = 1-3/16 inches) 100 Year 209 1 Z1_Boolean

Cdw #1 = #VALUE! 1.20(diameter = 1-1/4 inches) 500 Year 220 1 Z2_Boolean

Cdo #1 = #VALUE! 1.32(diameter = 1-5/16 inches) Zone3_Pulldown Message 1 Z3_Boolean

Overflow Weir #1 Angle = #VALUE! 1.45(diameter = 1-3/8 inches) 1 Opening Message

CLOG #2= #VALUE! 1.59(diameter = 1-7/16 inches) Draintime Running

Cdw #2 = #VALUE! 1.73(diameter = 1-1/2 inches) Outlet Boolean Outlet Rank Total (1 to 4)

Cdo #2 = #VALUE! 1.88(diameter = 1-9/16 inches) Vertical Orifice 1 1 1 1

Overflow Weir #2 Angle = #VALUE! 2.03(diameter = 1-5/8 inches) Vertical Orifice 2 0 0 Boolean

Underdrain Q at 100yr depth = 0.00 2.20(diameter = 1-11/16 inches) Overflow Weir 1 0 0 0 Max Depth

VertOrifice1 Q at 100yr depth = 0.07 2.36(diameter = 1-3/4 inches) Overflow Weir 2 0 0 0 500yr Depth

VertOrifice2 Q at 100yr depth = 0.00 2.54(diameter = 1-13/16 inches) Outlet Pipe 1 0 0 1 Freeboard

EURV_draintime_user = 2.72(diameter = 1-7/8 inches) Outlet Pipe 2 0 0 1 Spillway

Count_User_Hydrographs 0 2.90(diameter = 1-15/16 inches) 0 Spillway Length

CountA_3 (EURV & 100yr) = 0 3.09(diameter = 2 inches) Button Visibility Boolean FALSE Time Interval

CountA_4 (100yr Only) = 0 3.29(use rectangular openings) 1 Button_Trigger

0 Underdrain

1 WQCV Plate

0 EURV-WQCV Plate

0 EURV-WQCV VertOrifice

0 Outlet 90% Qpeak0 Outlet Undetained

S-A-V-D Chart Axis Override X-axis Left Y-Axis Right Y-Axis

minimum bound

maximum bound

UD-Detention, Version 3.07 (February 2017)

Detention Basin Outlet Structure Design

0

1

2

3

4

5

6

7

0.1 1 10

FLO

W [c

fs]

TIME [hr]

500YR IN

500YR OUT

100YR IN

100YR OUT

50YR IN

50YR OUT

25YR IN

25YR OUT

10YR IN

10YR OUT

5YR IN

5YR OUT

2YR IN

2YR OUT

EURV IN

EURV OUT

WQCV IN

WQCV OUT

0

0.5

1

1.5

2

2.5

0.1 1 10 100

PON

DIN

G D

EPTH

[ft]

DRAIN TIME [hr]

500YR

100YR

50YR

25YR

10YR

5YR

2YR

EURV

WQCV

0.00

10.00

20.00

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80.00

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4,000

6,000

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10,000

12,000

14,000

16,000

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

OU

TFLO

W [c

fs]

AREA

[ft^

2], V

OLU

ME

[ft^

3]

PONDING DEPTH [ft]

User Area [ft^2]

Interpolated Area [ft^2]

Summary Area [ft^2]

Volume [ft^3]

Summary Volume [ft^3]

Outflow [cfs]

Summary Outflow [cfs]

Outflow Hydrograph Workbook Filename:

Storm Inflow Hydrographs

The user can override the calculated inflow hydrographs from this workbook with inflow hydrographs developed in a separate program.

SOURCE WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK

Time Interval TIME WQCV [cfs] EURV [cfs] 2 Year [cfs] 5 Year [cfs] 10 Year [cfs] 25 Year [cfs] 50 Year [cfs] 100 Year [cfs] 500 Year [cfs]

5.36 min 0:00:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0:05:22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Hydrograph 0:10:43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Constant 0:16:05 0.01 0.01 0.01 0.01 0.02 0.04 0.07 0.14 0.28

0.932 0:21:26 0.03 0.03 0.02 0.04 0.06 0.11 0.19 0.36 0.760:26:48 0.08 0.08 0.05 0.09 0.15 0.28 0.49 0.93 1.950:32:10 0.21 0.23 0.15 0.25 0.41 0.77 1.34 2.57 5.37

0:37:31 0.24 0.26 0.17 0.29 0.47 0.88 1.55 3.00 6.340:42:53 0.23 0.24 0.16 0.27 0.44 0.84 1.47 2.85 6.04

0:48:14 0.21 0.22 0.14 0.24 0.40 0.76 1.34 2.60 5.500:53:36 0.18 0.19 0.12 0.21 0.35 0.67 1.18 2.30 4.900:58:58 0.15 0.16 0.10 0.18 0.29 0.57 1.01 1.97 4.221:04:19 0.13 0.14 0.09 0.16 0.26 0.50 0.88 1.72 3.681:09:41 0.12 0.13 0.08 0.14 0.23 0.45 0.79 1.56 3.331:15:02 0.09 0.10 0.06 0.11 0.19 0.36 0.64 1.27 2.741:20:24 0.07 0.08 0.05 0.09 0.15 0.29 0.51 1.03 2.221:25:46 0.05 0.06 0.03 0.06 0.11 0.21 0.38 0.77 1.701:31:07 0.04 0.04 0.03 0.04 0.08 0.15 0.27 0.56 1.261:36:29 0.03 0.03 0.02 0.03 0.06 0.11 0.20 0.41 0.911:41:50 0.02 0.02 0.02 0.03 0.05 0.09 0.16 0.32 0.711:47:12 0.02 0.02 0.01 0.02 0.04 0.07 0.13 0.27 0.591:52:34 0.02 0.02 0.01 0.02 0.03 0.06 0.11 0.23 0.501:57:55 0.01 0.02 0.01 0.02 0.03 0.06 0.10 0.20 0.44

2:03:17 0.01 0.01 0.01 0.02 0.03 0.05 0.09 0.18 0.402:08:38 0.01 0.01 0.01 0.02 0.02 0.05 0.09 0.17 0.372:14:00 0.01 0.01 0.01 0.01 0.02 0.03 0.06 0.12 0.272:19:22 0.01 0.01 0.01 0.01 0.01 0.03 0.05 0.09 0.202:24:43 0.00 0.01 0.00 0.01 0.01 0.02 0.03 0.07 0.142:30:05 0.00 0.00 0.00 0.00 0.01 0.01 0.02 0.05 0.112:35:26 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.03 0.07

2:40:48 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.02 0.052:46:10 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.042:51:31 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.022:56:53 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.013:02:14 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.013:07:36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:12:58 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:18:19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:23:41 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:29:02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:34:24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:39:46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:45:07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:50:29 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.003:55:50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:01:12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:06:34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:11:55 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:17:17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:22:38 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:28:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

4:33:22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:38:43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:44:05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:49:26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.004:54:48 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:00:10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:05:31 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:10:53 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:16:14 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:21:36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:26:58 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:32:19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:37:41 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:43:02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:48:24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:53:46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.005:59:07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.006:04:29 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.006:09:50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.006:15:12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.006:20:34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.006:25:55 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

UD-Detention, Version 3.07 (February 2017)

Detention Basin Outlet Structure Design

APPENDIX D

FIGURES

USGS The National Map: Orthoimagery. Data refreshed April, 2019.

National Flood Hazard Layer FIRMette

0 500 1,000 1,500 2,000250Feet

Ü

104°

43'51

.91"W

38°43'43.82"N

104°43'14.46"W

38°43'15.75"N

SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT

SPECIAL FLOODHAZARD AREAS

Without Base Flood Elevation (BFE)Zone A, V, A99

With BFE or Depth Zone AE, AO, AH, VE, ARRegulatory Floodway

0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone XFuture Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes. Zone XArea with Flood Risk due to Levee Zone D

NO SCREEN Area of Minimal Flood Hazard Zone X

Area of Undetermined Flood Hazard Zone D

Channel, Culvert, or Storm SewerLevee, Dike, or Floodwall

Cross Sections with 1% Annual Chance17.5 Water Surface Elevation

Coastal Transect

Coastal Transect BaselineProfile BaselineHydrographic Feature

Base Flood Elevation Line (BFE)

Effective LOMRs

Limit of StudyJurisdiction Boundary

Digital Data AvailableNo Digital Data AvailableUnmapped

This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standardsThe flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 10/23/2019 at 3:55:48 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes.

Legend

OTHER AREAS OFFLOOD HAZARD

OTHER AREAS

GENERALSTRUCTURES

OTHERFEATURES

MAP PANELS

8

1:6,000

B 20.2

The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location.

SUMMARY HYDROLOGY TABLE

Z:\111705.araco\dwg\civil\EX1.dwg, 10/23/2019 4:07:29 PM, DWG To PDF.pc3

SUMMARY HYDROLOGY TABLE

VEHICLE/RV

PARKING AND STORAGE

(EXISTING GRAVEL)

PARKING AREA

(EXISTING GRAVEL)

Z:\111705.araco\dwg\civil\D1.dwg, 10/23/2019 3:29:06 PM, DWG To PDF.pc3