Page 494 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

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452 Chapter 12 Urban Runoff and Combined Sewer Overflow Management

To implement the BMP selection method, ME DEP developed a series of eight matrices,
two matrices for each receiving water type (i.e., estuary, wetland, river, and stream). One matrix
is applied to development in designated priority watersheds and the other is applied to develop-
ment in nonpriority watersheds. A priority watershed list has been developed by ME DEP based
on environmental sensitivity, local support for water quality, and importance of the watershed
to the state. Example matrices for priority and nonpriority estuary watersheds are shown in
Tables 12.9 and 12.10.
Table 12.9 Priority Estuary Stormwater Control Matrix
Erosion and
Sediment Erosion and Water Quality
Level to Sediment Level to
Land Use Category Achieve Controls Achieve Storm Water Controls
Low-density residential, 2 ac/lot 1 Erosion and 1 Buffer 1
sediment 1
High-density residential, 2 ac/lot 2 Erosion and 3 Buffer 1 or 2
sediment 2 Wet pond 2
Infiltration 1 or 2
Created wetland 2
Commercial, 1 ac disturbed 1 Erosion and 1 Buffer 1
sediment 1
Commercial, 1–3 ac disturbed 1 Erosion and 2 Buffer 1 or 2
sediment 1 Infiltration 1
Swale 1
Commercial, ac disturbed 2 Erosion and 4 Buffer 1 or 2
sediment 2 Infiltration 1 or 2
Created wetland 2
Wet pond 2 or 3
Fertilizer control 1
Shallow impoundment 1
Intensive-use space 2 Erosion and 5 Buffer 1 or 2
(e.g., golf courses, nurseries) sediment 2 Fertilizer control 1
Pesticide control 1
Created wetland 2 or 3
Wet pond 2 or 3
Multihousing users 2 Erosion and 3 Buffer 1 or 2
sediment 2 Fertilizer control 1
Pesticide control 1
Created wetland 2
Wet pond 2
Infiltration 1 or 2
Industrial 1 ac disturbed 1 Erosion and 1 Buffer 1
sediment 1 Swale 1
Industrial 1–3 ac disturbed 1 Erosion and 2 Buffer 1 or 2
sediment 1 Swale 1
Industrial 3 ac disturbed 2 Erosion and 5 Buffer 1 or 2
sediment 2 Swale 1
Created wetland 2 or 3
Wet pond 2 or 3

Conversion factor: ac acre; 1 acre 0.4046 ha 0.004046 km 2
Source: U.S. Environmental Protection Agency, Stormwater Best Management Practice Design Guide—Volume 1—General Considerations (2004).