May 2010 Photo provided by the Trust for the National Mall U.S. Commission of Fine Arts Concept Review

2 AGENDA Introduction Vicinity Map Site Plan Primary Proposed Elements 1.18 inch curb water collection system 2.15 foot radii corners 3.Sand/compost soil system 4.Grading 5.Irrigation and water storage system Photo provided by the Trust for the National Mall

3 VICINITY MAP Pennsylvania Ave NW Maryland Ave SW Independence Ave SW Constitution Ave NW U.S. Capitol Washington Monument

4 SITE PLAN Project Area The Mall

5 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage Existing walkways to remain LANDSCAPE LAYOUT

6 Need for a Curb: Reinforces the grade and crowning set for each lawn panel in this project. Need efficient system to collect water runoff, to be stored in underground cisterns for grass watering. Meets the new Architectural Barriers Act Accessibility Standards (ABAAS). The existing edging does not meet these standards. Protects the new irrigation system. Reduces sidewalk gravel migration into grass panels. Helps to maintain a crisp grass edge. More appropriate to historic setting then steel edging. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage 18 INCH CURB WATER COLLECTION SYSTEM

7 B Option 1: Granite - White Mount Airy Granite Option 2: Precast Concrete

8 PERSPECTIVE 1 Proposed design with 15’ radii on panel corners and 18” wide curb system Existing condition

9 PERSPECTIVE 2 Proposed 18” wide curb system looking east from south walkway Existing condition looking east from south walkway

10 PERSPECTIVE 3 Proposed 18” wide curb system looking east from middle of Lawn Panel Existing condition looking east from middle of Lawn Panel

plan: When first constructed 4 roads ran east-west along the Mall. These roads were designed with a 15 foot radius and curb and gutter. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage 1936 AERIAL

12 Today’s Aerial: In the 1970s the inner roads became pedestrian paths and the 15 foot radius and curb and gutter was removed and replaced with metal edging. Today desire paths have inconsistently rounded the corners of each panel. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage TODAY’S AERIAL

13 Justification for 15 foot radii: Historically relevant curb radii to what was originally constructed in the 1930s. A radius at the corners of the panels will help mitigate pedestrian desire paths. 90 degree corners in the 1970’s no longer exist. Current corners are inconsistent depending upon wear patterns of pedestrians and take away from uniform appearance. Protecting the corners of the lawn panels will equate to less dead grass and brown spots on the Mall. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage 15 FOOT RADII Existing corner condition

14 Flowline of curb has a 15 foot radius Curb and gutter joints to be equally spaced 15 FOOT RADII A

15 Why a sand/compost soil system: To allow proper drainage of the soil to alleviate compaction in the root zone of the turf grass. Mitigating compaction will provide a healthier turf and show greater turf coverage on the panels. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage SAND/COMPOST SOIL SYSTEM

16 SAND/COMPOST SOIL SYSTEM C Netlon is a benign extruded plastic with a very strong memory that is resilient to compaction. Its purpose is to provide support to the soil system to help prevent compaction.

17 Rationale behind the grading plan: To restore a consistent even grade to the landscape. Adding a slight crowning will improve drainage and remove ponding. To accentuate the distant lawn views, while minimizing the visual presence of roadways, and walkways by crowning the panels. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage GRADING

18 GRADING Proposed gradingExisting grading Section Scale: 1”=10’ Horizontal 1”-2’ Vertical

19 Irrigation and water storage story: Proper irrigation is essential to maintaining healthy turf. Water harvesting provides a sustainable alternative to the use of potable water for irrigation. Cisterns for up to 500,000 gallons will store harvested water. Water will be collected from sidewalks, lawn panel run off and subsurface drainage. 5 primary proposed elements: 1 – 18 inch curb water collection system 2 – 15 foot radii on Lawn Panel corners 3 – sand/compost soil system 4 – grading 5 – irrigation and water storage IRRIGATION AND WATER STORAGE

20 IRRIGATION AND WATER STORAGE 2 x 250,000 gallon underground cisterns Lateral pipes connect drainage water to cisterns Underground pump station Drainage grates (6” x 48”) will be integrated into the gutter system every 36 feet to collect water. 36’

21 IRRIGATION AND WATER STORAGE Flush mounted sprinkler heads Irrigation feeder lines 2 x 250,000 gallon underground cisterns Underground pump station

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