MASTER DEVELOPMENT DRAINAGE PLAN FOR - NEPCO 2-9-15.pdf · MASTER DEVELOPMENT DRAINAGE PLAN FOR...

MASTER DEVELOPMENT DRAINAGE PLAN FOR MONUMENT HEIGHTS

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DRAINAGE REPORT STATEMENT 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 Town for drainage reports and said report is in conformity with the master plan of the drainage basin. I accept responsibility for any liability caused by any negligent acts, errors, or omissions on my part in preparing this report. Kyle R Campbell, Colorado P.E. #29794 Date DEVELOPER'S STATEMENT: I, the developer, have read and will comply with all of the requirements specified in this drainage report and plan.

Business Name: PINETREE PROPERTIES By: Title: Address: 8710 N. THORNDALE ROAD SUITE 120

TUCSON AZ 85742

Director of Development Services Date Conditions:


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TABLE OF CONTENTS: PURPOSE Page 1 GENERAL DESCRIPTION Page 1 EXISTING DRAINAGE CONDITIONS Page 1 PROPOSED DRAINAGE CHARACTERISTICS Page 4 DRAINAGE CRITERIA & STORMWATER QUALITY Page 8 FLOODPLAIN STATEMENT Page 8 DRAINAGE AND BRIDGE FEES Page 8 SUMMARY Page 8 REFERENCES Page 9 APPENDICES

VICINITY MAP

SOILS MAP (S.C.S. SURVEY)

F.E.M.A. MAP

CALCULATIONS

DRAINAGE MAP


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PURPOSE

This document is the Master Development Drainage Plan (MDDP) for Monument Heights. The purpose of

this MDDP is to identify major drainage features and facilities, and estimate peak rates of storm water runoff

from onsite and offsite sources. Also the purpose is to outline the necessary improvements to safely route

developed storm water runoff to adequate outfall facilities. The drainage improvements proposed in this

report are preliminary in nature and final drainage reports are required prior to commencing with any

development within the Monument Heights Sketch Plan that detail “to be constructed” drainage systems

including detention and storm water quality facilities.

GENERAL DESCRIPTION

Monument Heights consists of approximately 83.97 acres of parks and residential development located in a

portion of the Section 14 and a portion of section 23, township 11 south, range 67 west of the 6th principal

meridian, in the Town of Monument, County of El Paso, State of Colorado. The site is bounded on the north

by State Hwy 105, to the south by existing Bowstring Road, to the west by existing I-25 north bound off ramp

to Hwy 105 and to the east by the existing Village Center at Woodmoor residential development. The 83.97

acres is divided in half by the existing Jackson Creek Parkway ROW. The site is located both east and west

of Jackson Creek Parkway as it intersects State Hwy 105.

The average soil condition reflects Hydrologic Group “B” (Tomah-Crowfoot loamy sands) as determined by

the “Soil Survey of El Paso County Area,” prepared by the Soil Conservation Service (see map in Appendix).

EXISTING DRAINAGE CONDITIONS

The site is bisected by two different major drainage basins. The southerly portion of the site is located within

the Teachout Drainage Basin with the northerly portion being in the Dirty Woman Creek Drainage Basin.

Existing slopes range from 1% to 33% and ground cover is predominantly native grasses. The current

drainage patterns in the Dirty Woman Creek Drainage Basin travel in a westerly direction towards an existing

60” RCP culvert that crosses Jackson Creek Parkway, and eventually to a grated inlet with a 48” RCP culvert

that crosses an existing earth berm along the I-25 exit ramp. This 48” culvert drains to an existing 4’x8’ CBC

under the I-25 off ramp. The current drainage patterns in the Teachout Drainage Basin travel in a

southwesterly direction to existing roadside ditches along Bowstring Road and Jackson Creek Parkway. The

portion of the site located west of Jackson Creek Parkway drains in a southwesterly direction toward an

earthen berm and drainage ditch constructed along I-25 that eventually outfalls to Teachout Creek.

Design Point E-1 (Q5= 2 cfs, Q100= 13 cfs) consists of flows from Basins OS-3 and OS-4. Basin OS-3 is

2.85 acres of developed commercial retail development with an existing detention facility that discharges

directly onto the Monument Heights property. Basin OS-4 is 3.43 acres of developed Monument Villas

townhome property with and existing detention facility that discharges directly onto the Monument Heights

property. At the time of the writing of this MDDP existing drainage reports for these existing developments

were not available. It is assumed that these detention facilities adhere to the Town of Monument design

standard to release historic flows from detention facilities. Design Point E-1 represents a historic analysis of

the existing basin areas. These flows will need to be intercepted and accounted for in future final drainage

reports that will route these flows though the Monument Heights development.

Design Point E-2 (Q5= 1 cfs, Q100= 10 cfs) consists of flows from Basin OS-5. Basin OS-5 is 4.61 acres of

developed Monument Villas townhome property and a portion of the adjoining Trinity Lutheran Church

parking lot. At the time of the writing of this MDDP existing drainage reports for these existing developments

were not available. It is assumed that these detention facilities adhere to the Town of Monument design

standard to release historic flows from detention facilities. Design Point E-2 represents a historic analysis of

the existing basin areas. These flows will need to be intercepted and accounted for in future final drainage

reports that will route these flows though the Monument Heights development. Further detailed analysis of

the existing upstream facilities will take place with final design.

Design Point E-3 (Q5= 8 cfs, Q100= 51 cfs) consist of flows from Basins EX-1, OS-1 and Design Points E-

1 and E-2. Basin EX-1 is 18.38 acres of undeveloped land. Basin OS-1 is 4.25 acres of developed Trinity

Lutheran Church parking lot, building, and vacant land that directly drains on to the Monument Heights

property. At the time of the writing of this MDDP existing drainage reports for these existing developments

were not available. These flows will need to be intercepted and accounted for in future final drainage reports

that will route these flows though the Monument Heights development. Further detailed analysis of the

existing upstream facilities will take place with final design.

At Design Point E-3 there is an existing 60” RCP culvert with FES that currently crosses Jackson Creek

Parkway. Design Point E-3 represents the existing flows at this culvert crossing. Developed flows at this

culvert crossing will need to be detained to (Q5= 8 cfs, Q100= 51 cfs).

Design Point E-4 (Q5= 2 cfs, Q100= 9 cfs) consists of flows from the existing Village Center at Woodmoor

residential development. These are the flows at the end of the existing Knollwood drive that currently are

discharging directly onto the Monument Heights property. Upon the extension of Knollwood Drive into the

Monument Heights development, these flows will need to be accounted flow in future curb capacity and inlet

calculations in this Knollwood extension.

Design Point E-5 (Q5= 32.13 cfs, Q100= 113.64 cfs) consists of flows from the existing Village Center at

Woodmoor Pond 3A outfall and White Marble Drive that directly drains on to the Monument Heights

property. This development was studied as a part of the Drainage Analysis Addendum No. 2 Village Center

at Woodmoor,” prepared by Classic Consulting Engineers and Surveyors (CCES), approved August 2007 and

the “Drainage Letter Amendment for the Drainage Analysis Addendum Village Center at Woodmoor” by

CCES, approved October 2010. Existing Detention Pond 3A is a detention facility that was constructed in

2008. This facility was enlarged to provide over detention to reduce the release rate from contributing basins

and help the town address the pre-existing downstream erosion conditions. Design Point E-5 represents the

combined Pond 3A release as well as flows at the end of White Marble Drive that will need to be accounted

for with any street extension or development of the Monument Heights property near this design point.

Design Point E-6 (Q5= 5 cfs, Q100= 32 cfs) consists of flows from Basin EX-2, EX-3 and Design Point E-

4. Basin EX-2 is 4.43 acres of undeveloped land. Basin EX-3 is 17.03 acres of undeveloped land. Design

Point E-4 are existing flows at the end of existing Knollwood Drive. Flows from these existing basins

currently discharge into the existing roadside ditch along Jackson Creek Parkway. Design Point E-6 represents

the allowable discharge into the roadside ditch. Developed flows at this design point will need to be detained

to (Q5= 5 cfs, Q100= 32 cfs).

Design Point E-7 (Q5= 1 cfs, Q100= 4 cfs) consists of flows from Basin EX-4. Basin EX-4 is 1.92 acres of

undeveloped land at the northeast corner of the intersection of the I-25 northbound off ramp and Hwy 105.

Existing runoff sheet flows down a 3:1 slope to the existing roadside ditch along the off ramp. Developed

flows into this existing ditch will not exceed (Q5= 1 cfs, Q100= 4 cfs).

Design Point E-8 (Q5= 12 cfs, Q100= 79 cfs) consists of flows from Basin EX-5 and DP E-3. Basin EX-5

is 26.25 acres of undeveloped land. DP E-3 are flows from the existing 60” RCP culvert that crosses under

Jackson Creek Parkway and drains onto Basin EX-5. Existing flows from this culvert and Basin EX-5

currently travel in an overland swale to an existing CDOT grated inlet and 48” RCP culvert that carries flows

under an earth berm constructed with the interchange improvements at I-25 and Hwy 105. Flows from this

culvert are discharged into an existing 4’x8’ box culvert that crosses the Northbound off ramp of I-25. Design

Point E-8 represents the existing flows at this culvert crossing. Developed flows at this culvert crossing will

need to be detained to (Q5= 12 cfs, Q100= 79 cfs).

Design Point E-9 (Q5= 3 cfs, Q100= 23 cfs) consists of flows from Basin EX-6 and Basin EX-7. Basin EX-

6 is 11.20 acres of undeveloped land. Basin EX-7 is 4.76 acres of undeveloped land. Flows from these existing

basins currently discharge in a southwest direction into the existing ditch along the constructed earth berm

along I-25 and eventually to Teachout Creek. Design Point E-9 represents the allowable discharge into this

ditch. Developed flows at this design point will need to be detained to (Q5= 3 cfs, Q100= 23 cfs).

PROPOSED DRAINAGE CONDITIONS

The Monument Heights Master Plan consists of single family residential, townhome residential, single family

attached residential, multifamily residential and park areas. A Master Plan with assumed land use and drainage

basins is included in the Appendix of the MDDP that depicts design points and proposed detention facilities.

Design Point 1 (Q5= 2 cfs, Q100= 13 cfs) consists of flow from Design Point E-1 previously discussed.

Flows are from these offsite basins and detention facilities. At the time of the writing of this MDDP existing

drainage reports for these existing developments were not available. It is assumed that these detention

facilities adhere to the Town of Monument design standard to release historic flows from detention facilities.

Flows will need to be intercepted and routed though the Monument Heights development. Consideration

for these flows will be taken into account with the future planning of development of Monument Heights.

Design Point 2 (Q5= 1 cfs, Q100= 10 cfs) consists of flow from Design Point E-2 previously discussed.

Flows from these offsite basins or detention facilities. At the time of the writing of this MDDP existing

drainage reports for these existing developments were not available. It is assumed that these detention

facilities adhere to the Town of Monument design standard to release historic flows from detention facilities.

Flows will need to be intercepted and routed though the Monument Heights development. Consideration

for these flows will be taken into account with the future planning of development of Monument Heights.

Design Point 3 (Q5= 32 cfs, Q100= 97 cfs) consists of flows from Basin A, Basin B, Basin C, as well as offsite

flows from DP 1 and DP 2. Basin A is 12.60 acres of proposed Townhome development. Basin B is 2.00

acres of proposed park area. Basin C is 9.50 acres of proposed Single Family Attached development. Flows

from the development within these basins will be routed in future roads to inlets and storm sewer that will

convey flows to a proposed detention facility (Pond #1) that will discharge flows to an existing 60” RCP

culvert that crosses Jackson Creek Parkway. Developed flows at this location will be reduced to (Q5= 8 cfs,

Q100= 51 cfs) as determined by Design Point E-3. In order to achieve the allowable release rates an estimated

3.3 ac-ft. facility is required at this location. An outlet structure will be designed to release the EURV volume

with a 72-hour drain time, a full spectrum requirement, and restrict the large event release to the allowable

rates. Any development with in Basins A, B or C will require a final drainage report that will detail the

requirements this detention facility and the proposed onsite storm sewer routing developed flows to this

detention facility.

Design Point 4 (Q5= 8 cfs, Q100= 51 cfs) represents the allowable release from proposed Pond #1 that will

need to be accounted for upon development west of Jackson Creek Parkway in the existing 60” RCP culvert

crossing.

Design Point 5 (Q5= 2 cfs, Q100= 9 cfs) consists of flows from the existing Village Center at Woodmoor

residential development. These are the anticipated flows at the end of the existing Knollwood drive that

currently are discharging directly onto the Monument Heights property. Upon the extension of Knollwood

Drive into the Monument Heights development, these flows will need to be accounted for in future curb

capacity and inlet calculations in this Knollwood extension.

Design Point 6 (Q5= 18 cfs, Q100= 58 cfs) consists of flows from Basin D and DP 5. Basin D is 16.50 acres

of proposed single family residential development. Flows from the development within this basins will be

routed in future roads to inlets and storm sewer that will convey flows to a proposed detention facility (Pond

#2) that will discharge flows to an existing roadside ditch along Jackson Creek Parkway. Developed flows at

this location will be reduced to (Q5= 5 cfs, Q100= 32 cfs) as determined by Design Point E-6. In order to

achieve the allowable release rates an estimated 1.25 ac-ft. facility is required at this location. An outlet

structure will be designed to release the EURV volume with a 72-hour drain time, a full spectrum requirement,

and restrict the large event release to the allowable rates. Any development with in Basin D will require a final

drainage report that will detail the requirements this detention facility and the proposed onsite storm sewer

routing developed flows to this detention facility.


be released into the existing roadside ditch along Jackson Creek Parkway. A final drainage report will be

required for any development with in Basin D that will detail outlet treatment, protection of the discharge

point and the roadside ditch.

Design Point 8 (Q5= 32 cfs, Q100= 113 cfs) consists of flows from the existing Village Center at Woodmoor

Pond 3A outfall and White Marble Drive that directly drains on to the Monument Heights property see Design

Point E-5 previously mentioned. Per the Monument Heights Master Plan, the area that is impacted by this

direct release is planned to remain a drainage way and future Park area with minimal development. Flows

from the existing detention facility and White Marble Drive will continue to travel in its natural path towards

the existing roadside ditch along Bowstring Drive without any additional developed flows added from the

Monument Heights development.

Design Point 9 (Q5= 34 cfs, Q100= 119 cfs) consists of flows from Basin F, Basin G, Basin H, and DP 4.

Basin F is 15.80 acres of proposed multi-family residential development. Basin G is 9.00 acres of proposed

single family residential development. Basin H is 4.00 acres of proposed park area. Flows from the

development within these basins along with the allowable release from Pond #1, will be routed in future roads

to inlets and storm sewer that will convey flows to a proposed detention facility (Pond #3) and will discharge

flows to an existing 48” RCP culvert that crosses the earthen berm along the I-25 northbound off-ramp to an

existing 4’x8’ box culvert under the off-ramp. Developed flows at this location will be reduced to (Q5= 12

cfs, Q100= 79 cfs) as determined by Design Point E-8. In order to achieve the allowable release rates an

estimated 1.03 ac-ft. facility is required at this location. An outlet structure will be designed to release the

EURV volume with a 72-hour drain time, a full spectrum requirement, and restrict the large event release to

the allowable rates. As an option for the detention requirements, proposed Pond#1 and Pond#3 may be

combined into 1 facility located at Pond #3. This would allow for flexibility in layout and design of future

development east of Jackson Creek Parkway. If this option is utilized, the release rates from Pond #3 will

still need to be adhered to and flows into the existing 48” RCP culvert will still need to be reduced to historic

rates. Developed flows east of Jackson Creek Parkway will be limited to the capacity of the existing 60” RCP

culvert unless this culvert crossing is upgraded with any improvements to Jackson Creek Parkway. Any

development with in Basins F, G or H will require a final drainage report that will detail the requirements of

this detention facility and the proposed onsite storm sewer routing developed flows to this detention facility.

Design Point 10 (Q5= 12 cfs, Q100= 79 cfs) represents the allowable release from proposed Pond #3 that

will be released into the existing 48” RCP culvert to the I-25 4’x8’ box culvert.

Design Point 11 (Q5= 11 cfs, Q100= 33 cfs) consists of flows from Basin I. Basin I is 11 acres of proposed

single family residential development. Flows from the development within this basin will be routed in future

roads to inlets and storm sewer that will convey flows to a proposed detention facility (Pond #4) that will

discharge flows to an existing ditch along a earth berm adjacent to I-25 and eventually to Teachout Creek.

Developed flows at this location will be reduced to (Q5= 3 cfs, Q100= 23 cfs) as determined by Design Point

E-9. In order to achieve the allowable release rates an estimated 0.60 ac-ft. facility is required at this location.

An outlet structure will be designed to release the EURV volume with a 72-hour drain time, a full spectrum

requirement, and restrict the large event release to the allowable rates. Any development with in Basin I will

require a final drainage report that will detail the requirements this detention facility and the proposed onsite

storm sewer routing developed flows to this detention facility.


be released into the existing ditch along a earth berm adjacent to I-25 and eventually to Teachout Creek. A

final drainage report will be required for any development with in Basin I that will detail outlet treatment,

protection of the discharge point and the existing ditch.

PROPOSED DETENTION FACILITIES

All proposed detention facilities will be an Extended Detention Basin (EDB) storm water quality facilities

with a full spectrum outlet box. Detention facilities will drain the EURV volume in a 72 hour drain time and

will be constructed with associated fore bays, trickle channels, micro pool, well screen, orifice plate, and 100

year outlet conveyance per the current drainage criteria manual. Detention ponds will be owned and

maintained by the Town of Monument. Final drainage reports will be required outlining specific details about

the requirements of these proposed detention facilities.

DRAINAGE CRITERIA STORMWATER QUALITY

Hydrologic calculations were performed using the City of Colorado Springs/El Paso County Drainage Criteria

Manual, as revised in May 2014. The Rational Method was used to estimate storm water runoff anticipated

from design storms for the 5 year and 100 year recurrence interval.

FLOODPLAIN STATEMENT

No portion of this site is located within a floodplain as determined by the Flood Insurance Rate Maps

(F.I.R.M.) Map Number 08041C 0278F effective date, March 17, 1997 (See Appendix).

DRAINAGE AND BRIDGE FEES

This area lies within Teachout Drainage Basin and the Dirty Woman Creek Drainage Basin boundaries.

Drainage and Bridge fees will be determined at the time of final drainage report and final plat for development

within the Monument Heights Master Plan.

SUMMARY

The proposed Monument Heights Master Plan is divided between the Teachout Creek and the Dirty Woman

Creek drainage basins. Developed and historic flow calculations have identified future outfall locations and

detention pond with preliminary sizes and have been recommended by this MDDP. All points of storm water

release from the proposed site will be at or below the calculated historic flow quantities. The development of

the proposed Monument Heights will not hinder any downstream facilities or property and in no situation

shall the released flows be greater than that which currently exists in the historic/existing conditions. All

future drainage facilities will be sized with the current Drainage Criteria Manual and full-spectrum storm water

quality requirements. Upon development of the individual parcels within the Monument Heights Master Plan,

separate Final Drainage Reports will be required to be submitted and approved by the Town on Monument

that details all storm systems, pond design, and fee calculation. The quantity, location and configuration of

future detention facilities may vary based upon the final design analysis.

PREPARED BY: Classic Consulting Engineers & Surveyors, LLC David L Gibson, P.E. Project Engineer dlg/246000/Reports/mddp.doc

REFERENCES 1. City of Colorado Springs/County of El Paso Drainage Criteria Manual dated May 2014. 2. “Drainage Analysis Addendum No.2 Village Center at Woodmoor” Classic Consulting Engineers and

Surveyors, dated June 2009. 3. “Village Center @ Woodmoor Filing No.1” Berge-Brewer and Associates, Inc., dated January 2005. 4. “Drainage Basin Planning Study Dirty Woman Creek and Crystal Creek El Paso County,” Kiowa

Engineering Corporation, dated Septemtber 1993.

APPENDIX

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