Drainage Criteria Manual

Drainage Criteria Manual Volume 2

The City of Colorado Springs Drainage Criteria Manual Volume 2 (DCMV2) was adopted as El Paso County's stormwater quality design criteria, with the intent to use Appendix I of the El Paso County's Engineering Criteria Manual (ECM) to provide additions and revisions applicable to the County in order to expand its scope to cover rural areas and other situations specific to the County. The goal has been to maintain consistency between criteria used in the County and in the City of Colorado Springs. Please refer to section 1.3 of Appendix I of the ECM for additional clarification.

Table of Contents (Click on the underlined item to bring up that section.)

List of Abbreviations				i
Abbreviations of Structural BMPs in the Manual				ii
Standard Symbols				iii
Definitions				iv
1.0	Overview and Purpose			1-1
2.0	Stormwater Quality Management			2-1
	2.1	Environmental Impacts of Runoff		2-1
	2.2	Stormwater Runoff Constituents and Sources		2-1
	2.3	NPDES Permit Regulations		2-2
			Phase I Stormwater Regulations	2-3
			Phase II Stormwater Regulations	2-4
			Non-Stormwater Discharges	2-5
	2.4	Summary		2-7
3.0	Construction Stormwater Management			3-1
	3.1	Introduction		3-1
	3.2	Erosion and Stormwater Quality Control Plan		3-2
		General Principles		3-2
		Plan Elements		3-6
		Best Management Practices (BMPs)		3-11
		Additional Information Requirements/Modifications to Plan		3-15
		Plan Implementation		3-15
		City Inspections		3-16
		Record Keeping		3-16
		Guarantee		3-16
		Relation to CDPs Stormwater Requirements		3-16
		Consistency and Compliance with Other Plans and Regulations		3-16
	3.3	Construction BMP Factsheets		3-17
	Guidelines for Implementing Best Management Practices			3-18
		For Any Construction Site		3-18
		For Slopes		3-18
		For Storm Drain Inlets		3-18
	Check Dam			3-19
	Erosion Control Blankets			3-21
	Inlet Protection			3-24
	Mulching			3-29
	Sediment Basin			3-31
	Silt Fence			3-34
	Slope Drain			3-38
	Straw Bale Barriers			3-40
	Street Wash Water Associated with Construction Activities			3-43
	Surface Roughening			3-44
	Temporary Seeding			3-46
	Temporary Swale			3-48
	Vehicle Tracking			3-52
	3.4	Construction Site Inspections		3-55
			Types of Inspections	3-55
			Frequency and Types of Inspections of Construction Sites	3-58
	3.5	Construction Enforcement Strategy		3-58
			Goal of Strategy	3-58
			Policies	3-58
			Definitions	3-59
			Enforcement Procedures	3-60
4.0	New Development Stormwater Management			4-1
	4.1	New Development Planning		4-1
			Overview	4-1
			Four-Step Process	4-2
			Other BMPs	4-4
			Employing Runoff Reduction Techniques	4-5
			Providing Water Quality Capture Volume (WQCV)	4-13
			Structural BMP Effectiveness	4-23
	4.2	New Development BMP Fact Sheets		4-24
	Grass Buffer			4-25
		Description		4-25
		General Application		4-25
		Advantages/Disadvantages		4-26
		Design Considerations		4-26
		Design Procedure and Criteria		4-26
		Design Example		4-28
		Maintenance Recommendations		4-28
	Grass Swale (GS) Sedimentation Facility			4-32
		Description		4-32
		General Application		4-32
		Advantages/Disadvantages		4-33
		Design Considerations and Criteria		4-33
		Design Procedure and Criteria		4-34
		Design Example		4-35
		Maintenance Recommendations		4-35
	Modular Block Porous Pavement (MBP)			4-38
		Description		4-38
		General Application		4-38
		Advantages/Disadvantages		4-39
		Design Considerations		4-40
		Design Criteria and Procedures		4-40
		Design Example		4-41
		Maintenance Recommendations		4-41
	Porous Pavement Detention (PPD)			4-47
		Description		4-47
		General Application		4-47
		Advantages/Disadvantages		4-47
		Design Considerations		4-47
		Design Procedure and Criteria		4-48
		Design Example		4-49
		Maintenance Recommendations		4-49
	Porous Landscape Detention (PLD) - Sedimentation Facility			4-53
		Description		4-53
		General Application		4-53
		Advantages/Disadvantages		4-55
		Design Considerations		4-56
		Design Procedure		4-56
		Design Example		4-57
		Maintenance Recommendations		4-57
	Extended Detention Basin (EDB) - Sedimentation Facility			4-61
		Description		4-61
		General Application		4-61
		Advantages/Disadvantages		4-62
		Design Considerations		4-63
		Design Procedure and Criteria		4-64
		Design Example		4-67
		Maintenance Recommendations		4-67
	Sand Filter Extended Detention Basin (SFB)			4-75
		Description		4-75
		General Application		4-75
		Advantages/Disadvantages		4-75
		Design Procedure and Criteria		4-76
		Design Example		4-77
		Maintenance Recommendations		4-77
	Constructed Wetlands Basin (CWB) - Sedimentation Facility			4-81
		Description		4-81
		General Application		4-82
		Advantages/Disadvantages		4-82
		Design Considerations		4-83
		Design Procedure and Criteria		4-83
		Design Example		4-86
		Maintenance Recommendations		4-86
	Retention Pond (RP) - Sedimentation Facility			4-94
		Description		4-94
		General Application		4-94
		Advantages/Disadvantages		4-95
		Design Considerations		4-96
		Design Procedure and Criteria		4-97
		Design Example		4-100
		Maintenance Recommendations		4-100
	Constructed Wetlands Channel (CWC) - Sedimentation Facility			4-108
		Description		4-108
		General Application		4-108
		Advantages/Disadvantages		4-109
		Design Considerations		4-110
		Design Procedure and Criteria		4-110
		Design Example		4-111
		Maintenance Recommendations		4-111
	Covering Storage and Handling Areas			4-114
		Description		4-114
		General Application		4-114
		Advantages/Disadvantages		4-114
	Spill Containment and Control			4-116
		Description		4-117
		General Application		4-118
		Advantages/Disadvantages		4-117
	4.3	Typical Structural Details		4-118
	4.4	Procedures for Assessment of Structural Controls for Retrofitting Water Quality Features		4-133
			Retrofit Screening - Qualitative Criteria	4-134
			Quantitative Assessment	4-135
			Economic Feasibility	4-137
			Final Alternative Selection	4-137
	Appendix A New Development Design Forms			A-1
	Appendix B Material Specifications			A-19
	Appendix C Inspection Checklist - Grading Erosion and Stormwater Quality Controls			A-23

	Tables
	SQ-1	Urban Runoff Pollutants		2-2
	SQ-2	Non-stormwater Discharges		2-6
	SQ-3	Allowable Non-Stormwater Discharges		2-6
	CS-1	Enforcement Options		3-61
	ND-1	Illustration of Selection and Location Options for WQCV Facilities for the		4-22
			Development Parcel on Figure ND-8
	ND-2	BMP Pollutant Removal Ranges for Stormwater Runoff and Most Probable		4-23
			Range for BMPs
	GB-1	Irrigated Grass Buffer Strip Maintenance Considerations		4-28
	GS-1	Grass-Lined Swale Maintenance Considerations		4-35
	MBP-1	Modular Block Porous Pavement Maintenance Considerations		4-41
	PPD-1	Porous Pavement Detention Maintenance Considerations		4-49
	PLD-1	Porous Landscape Detention Maintenance Considerations		4-57
	EDB-1	Extended Detention Basin Maintenance Considerations		4-67
	SFB-1	Sand Filter Detention Basin Maintenance Considerations		4-77
	CWB-1	Constructed Wetlands Maintenance Considerations		4-86
	RP-1	Retention Pond Basin Maintenance Considerations		4-100
	CWC-1	Constructed Wetlands Maintenance Considerations		4-111
	ND-3	BMP Removal Ranges for TSS		4-136
	MT-1	Gradation Requirements for Riprap		-19
	MT-2	Physical Requirements for Temporary Silt Fence Geotextiles		A-20
	MT-3	Physical Requirements for Drainage Geotextiles		A-21

	Figures
	CD-1	Check Dam		3-20
	ECB-1	Erosion Control Blanket		3-22
	ECB-2	Erosion Control Blanket		3-23
	IP-1	Filter Fabric Inlet Protection		3-25
	IP-2	Straw Bale Inlet Protection		3-26
	IP-3	Block and Gravel Bag Curb Inlet Protection		3-27
	IP-4	Curb Sock Inlet Protection		3-28
	MU-1	Mulching		3-30
	SB-1	Sediment Basin		3-32
	SB-2	Outlet Sizing		3-33
	SF-1	Silt Fence		3-35
	SF-2	Silt Fence		3-36
	SF-3	Silt Fence Joints		3-37
	SD-1	Slope Drain		3-39
	SBB-1	Straw Bale Barrier		3-41
	SBB-2	Straw Bale Barrier		3-42
	TS-1	Temporary Seeding		3-47
	TSW-1	Temporary Swale		3-49
	TSW-2	Temporary Swale		3-50
	TSW-3	Swale Linings		3-51
	VT-1	Vehicle Tracking		3-53
	VT-2	Vehicle Tracking		3-54
	ND-1	Imperviousness to use with Water Quality Capture Volume		4-9
	ND-2	Examples of Minimizing Directly Connected Impervious Areas -		4-10
			Residential and Commercial
	ND-3	Examples of MDCIA for Multi-Family Residential Development		4-11
	ND-4	Typical Application of Modular Block Porous Pavement		4-12
	ND-5	Example of Porous Pavement Detention for Multi-Family		4-16
			Residential Development
	ND-5A	Example of Porous Landscape Detention for Multi-Family		4-17
			Residential Development
	ND-6	Examples of Porous Pavement and Porous Landscape Detention		4-18
			for Commercial Development
	ND-7	Decision Tree for WQCV BMP Selection		4-20
	ND-8	Illustration of Selection and Location Options for WQCV Facilities		4-21
	GB-1	Application of Grass Buffers		4-30
	GS-1	Profile and Sections of a Grass Swale		4-36
	MBP-1	Modular Block Porous Pavement Cross Section		4-42
	MBP-1A	Typical Grasspave Detail		4-43
	MBP-2	Modular Block Porous Pavement		4-44
	MBP-3	Typical Applications of Modular Block Porous Pavement		4-45
	PPD-1	Porous Pavement Detention		4-50
	PPD-2	Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event		4-51
	PLD-1	Porous Landscape Detention		4-58
	PLD-2	Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event		4-59
	EDB-1	Plan and Section of an Extended Detention Basin Sedimentation Facility		4-69
	EDB-2	Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event		4-70
	EDB-3	Water Quality Outlet Sizing: Dry Extended Detention Basin with a 40-Hour		4-71
			Drain Time of the Capture Volume
	SFB-1	Sand Filter Basin		4-78
	SFB-2	Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event		4-79
	CWB-1	Plan and Profile of a Constructed Wetland Basin Sedimentation Facility		4-88
	CWB-2	Water Quality Capture Volume (WQVC), 80th Percentile Runoff Event		4-89
	CWB-3	Water Quality Outlet Sizing: Constructed Wetland Basin with a 24-Hour Drain		4-90
			Time of the Capture Volume
	RP-1	Plan and Section of a Retention Pond - Sedimentation Facility		4-102
	RP-2	Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event		4-103
	RP-3	Water Quality Outlet Sizing: Retention Pond - Sedimentation Facility with a		4-104
			12-Hour Drain Time of Capture Volume
	CWC-1	Plan and Section of a Constructed Wetland Channel		4-112