Equinox (Spring & Fall) Summer Solstice Winter Solstice

4.3.3 Light and Shadow

1

The anticipated impacts on light and shadow are 2

depicted in the diagrams for various times and 3

seasons.

4

ALTERNATIVE A Shadow Study

Figure 4-9: Alternative A Shadow Study

9 am

Equinox (Spring & Fall)

Summer Solstice

Winter Solstice

Noon

3 pm

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ALTERNATIVE B

1

Shadow Study

2

3

Figure 4-10: Alternative B Shadow Study

Equinox (Spring & Fall)

9 am

Summer Solstice

Winter Solstice

Noon

132

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3 pm

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ALTERNATIVE C

1

Shadow Study

2

3

Figure 4-11: Alternative C Shadow Study

Equinox (Spring & Fall)

9 am

Summer Solstice

Winter Solstice

Noon

3 pm

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4.4 Flooding

1 potential to integrate the design into the natural systems of the White Oak FRC site.

42 required to be non-erosive.

43

86 Stormwater Runoff Requirements for Federal

128

87 Projects under EISA 438 (EPA, 2009)

129

Based on a review of FEMA Flood Insurance Rate Maps (FIRM), floodplains for Paint Branch and several tributaries to Paint Branch are found on portions of the FRC and within the study area (see Figure 13). The FRC is mapped on FIRM Panel 24031C0390D, effective September 29, 2006 (FEMA, 2006). These floodplains have been designated Zone AE which indicates a detailed study was performed to map the floodplain and Base Flood Elevations (BFEs), the elevation to which the flood is expected to rise during the 100-year storm, have

2

3 Potential types of LID/BMP facilities for the 4 expanded FDA Campus are: Micro-bioretention 5 (Structural walled micro-bioretention may be 6 used in lieu of graded micro-bioretention where 7 space limitations dictate), Bio-swales (on road 8 sides), Rooftop Rainwater Harvesting (Typical reuse 9 methods are toilet flushing and cooling tower 10 makeup water), Green Roof/Partial Green Roof 11 (Green roof with 4" media provides 38% of the 12 required MDE Environmental Site Design Volume

44 Construction would be authorized under the

88 ? Guidelines for Environmental Management of

130

45 NPDES General Permit for Stormwater Associated

89

Development in Montgomery County (M-NCPPC, 131

46 with Construction Activity. Notices of Intent (NOI) 90 2000)

132

47 would be filed and NPDES General Permits for

91 ? NPDES General Permit for Stormwater Associated 133

48 Construction would be obtained for all new work.

92

with Construction Activity, administered by MDE 134

49 During construction, BMPs such as silt fence, erosion 93

50 matting, inlet protection, sediment traps, sediment 94 ? NPDES General Permit for Discharges from State 135

51 basins, and revegetation of exposed sediment

95

and Federal Small Municipal Separate Storm

136

52 would be implemented to minimize soil erosion and 96

Sewer Systems (MS4s), administered by MDE

137

53 stormwater pollution. Stormwater management

97 ? Maryland State Programmatic General Permit 5 138

54 plans and erosion and sediment control plans would 98

(MDSPGP-5), co-administered by USACE and MDE 139

been calculated. The floodplains on the FRC are

13 (ESDv)), Pervious Pavements (The best opportunities 55 be prepared and submitted to MDE for review and 99

primarily confined to the narrow channels of the

14 on the campus are likely to be fire lanes, sidewalks, 56 approval prior to construction. MDE enforces a

100

streams and do not span large areas. None of the 15 paths, and other hardscape areas), Submerged

57 maximum limit of 20 acres of disturbed ground at 101

proposed alternatives involve development within 16 Gravel Wetlands (MDE will generally accept these if 58 any time. All disturbed areas would be permanently 102

the 100-year floodplain. The implementation of the 17 alternative ESD BMPs are not feasible), Tree Planting, 59 revegetated and stabilized following construction. 103

proposed alternatives complies with Executive Order 18 and Stream Restorations (Tree planting and stream 60 Temporary impacts to streams and wetlands would 104

11988 and the PBS GSA Floodplain Management

19 restoration can at times be credited toward meeting 61 be restored to pre-construction conditions to the 105

Desk Guide, 2016. There would be no significant

20 water quality requirements).

62 maximum extent practicable following construction, 106

impacts to floodplains under any of the proposed 21

63 including contour and elevation restoration,

107

Action Alternatives.

22 Roadways would maximize use of bio swales.

64 revegetation with native species, streambank

108

23 Office buildings would maximize the use of rooftop 65 stabilization, and stream substrate replacement.

109

4.5 Proposed Stormwater Management

24 rainwater harvesting as well as green roofs. Any 25 untreated storm runoff from roads, buildings, and

parking structures would be conveyed to new non-

66

110

67 Stormwater quantity and quality control measures 111

68 would be designed and implemented in accordance 112

Figures 4-12, 4-13, and 4-14 show the proposed stormwater management plans for each Action Alternative.

The State of Maryland Environmental Site Design (ESD) strategies would be implemented to the maximum extent practicable. LEED and SITES points for stormwater management would be pursued for each building. Low Impact Development (LID) strategies would be employed in accordance with the Technical Guidance on Implementing the Storm Water Runoff requirements for Federal Projects under Section 438 of the Energy Independence and Security Act (EISA 438). Strategies to incorporate SWM facilities into the site as amenities and spatial drivers would be pursued, as well as exploring the

26 structural ESD/BMP facilities such as bio-retention 27 areas. Once ESD measures have been implemented 28 to the maximum extent practicable (MEP), then 29 structural and other non-ESD type BMP facilities 30 could be utilized. An existing SWM pond (Pond #3) 31 located at the east end of the central commons 32 would be removed and replaced with a walled or 33 underground SWM facility. The existing SWM pond 34 (SHA Pond #2) located north of Michelson Road, 35 and adjacent to New Hampshire Avenue (MD 650) 36 would be removed and replaced by a submerged 37 gravel wetland located south of Michelson Road. 38 The other existing stormwater facilities on the FDA 39 Campus may be retrofitted, relocated, or replaced 40 as necessary. These areas would drain to new storm 41 pipe systems that would in turn outfall to existing

tributaries of Paint Branch. Outfalls would be

69 with the following regulations, permits and guidance 113

70 documents:

114

71

115

72 ? COMAR 26.17.01 Erosion and Sediment Control 116

73 ? COMAR 26.17.02 Stormwater Management

117

74 ? Maryland Standards and Specifications for Soil 118

75

Erosion and Sediment Control (MDE, 2011)

119

76

77 ? Maryland Stormwater Management and Erosion 120

78

& Sediment Control Guidelines for State and

121

79

Federal Projects (MDE, 2015)

122

80 ? Maryland Stormwater Design Manual, Volumes I 123

81

& II (MDE, 2000) and Supplement 1 (MDE, 2009) 124

82 ? Section 438 of the Energy Independence and

125

83 Security Act of 2007 (EISA)

126

84 ? Technical Guidance on Implementing the

127

85

134

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