Welcome to the Landscape Design Association Winter Workshop

Transcription

1 Welcome to the Landscape Design Association Winter Workshop The Wonderful World of Grading & Drainage? Presented by Paul Laiblin - Design Production Manager Scott Byron & Co., Inc.

2 The Wonderful World of Grading & Drainage?

3 The Scary World of Grading & Drainage? It s OK, it s just landscaping! (nothing to be afraid of) Technical, challenging Functional/Pragmatic Involves math (Boo) Can be confusing, difficult, constraining ULTIMATELY, HOWEVER THESE ARE DESIGN ISSUES! Solves functional site issues Creates transitions, movement Creates visual interest Forces us to work creatively within site constraints What & Why More broadly, grading & drainage are ways of manipulating landform (i.e. site topography) or The lay of the Land to create and manage outdoor space to fulfill client needs and design objectives

4 Landform Provides base, structure for landscape design with both utilitarian and artistic implications Regional Landform Site Specific Landform Grading & Drainage two sides of the same coin Grading Simply put, the art of shaping the land and modifying site topography Used To Modify site for development (i.e. housing, paving, landscape development etc.) Facilitate movement of water on a site (drainage or water management) In conjunction with walls, steps, hardscape elements to Prevent soil erosion Facilitate grade transitions Create more level usable space Create movement/destination in the landscape Create visual interest

5 Drainage - Let s change our Thinking! The Art & Science of Site Water Management Used to Prevent flooding and structural damage Create functional usable space Create visual interest & focal points (i.e. ponds, streams, water features) Recharge ground water Manage run off & sedimentation/pollution Facilitate plant growth

6 Drainage - Let s Change our Thinking Some More! Old Thinking 1) Manipulate site to achieve development goals 2) Divert and remove water from site ASAP 3) Build lots of infrastructure 4) Treat soil like dirt 5) Water is a waste product 6) Cover as much of site as possible with hardscape & structures 7) Who cares where water ends up 8) Each site is an island unto itself

7 New Thinking 1) Work with constraints of the site to inform your design 2) Manage water on site and release slowly 3) Minimize infrastructure 4) Manage and maintain soil structure & quality 5) Water is a resource 6) Work within limits of allowable lot coverage 7) Respect the water cycle and where water is discharged 8) Think holistically with a systems approach Drainage - Let s Change our Thinking Some More!

8 You already know more than you think!! In addition, the following usually applies to sites in our area: READING THE LANDSCAPE As part of site analysis consider the following in your design and construction planning as it relates to grading & drainage. What is the cultural, geographic, and geologic history of the site? What might it have looked like in its pre-development state? Are there restoration or mitigation efforts that come into play? How does this inform/inspire landscape & site development, including grading and drainage. What are seasonal sun/shade and prevailing wind patterns? How might this influence site topography, design goals, plant choices & grading and drainage concerns? What is existing vegetation like and what might this tell us about soil or drainage conditions? What is the lay of the land, i.e., how is the site pitched or sloped? What are drainage patterns? Is this a known floodplain? Are there low or high spots, existing swales, drainage structures, or detention/retention areas? Is water pitched away from structures? Where do downspouts and sump pump lines discharge? Does any of the above present opportunities for alternative water management strategies rain gardens, bio-swales, permeable paving, etc.). Generally flat topography which presents drainage problems. Former prairie soils with clay underlayments-usually good fertility but poorly drained and with poor aeration. Remnant Oak/Hickory Savannah/Prairie remnants, especially on older, larger less disturbed sites. Can be damaged or destroyed by insensitive site management. Possible sand or gravel sub-soils in pockets along Lake Michigan, along Ridge Road on North Shore, and in areas of McHenry County. Some sites in our area are filled in former swamps or wetlands, and may have floodplain and drainage issues. Commercial and new construction sites will generally present more problems with site management (debris, soil compaction) than older, more established sites.

9 You already know more than you think!! How? Due Diligence/Research Regulatory Issues Local, State, Federal Permit Requirements Impervious surface (lot coverage) May need permits for significant grade changes or hardscape development Wetland issues Compensatory storage Floodplain fema.gov or floodsmart.gov Storm sewer connection Army Corps of Engineers Alternative strategies? Bio Swale Dry Creek Green Roof Permeable Paving Assemble a Team Landscape Designer/Architect Civil Engineer & Surveyor Consultants Wetland/Natural areas Green Roof Bio Retention/Rain Gardens Drainage contractors Excavator Landscape contractor Village Officials Client!!

10 How Putting it all Together Reading Grading Plans Grading plans depict three dimensional landforms through the use of contour lines. Contour lines are graphic lines that denote a constant elevation above a given elevation at a predefined spot, often referred to as a datum point or benchmark. They are the best way in which to illustrate in two dimensions a landscape that exists in three dimensions length, width, and height. Graphically, contours in their preconstruction or existing form are depicted most often as dashed lines, while contours that are changed, or will be changed during construction, are depicted as solid lines. In many instances, parts of contours may remain unchanged (shown as dashed lines), while other parts of the same contour will be altered to give the landscape its desired shape (depicted with a solid line). As contour lines come closer together, the landform gets steeper; as they move farther apart, the landform becomes flatter. Benchmark (B.M.) A known grade point or elevation to which other project grades are referenced. Allows us to determine differences in Height between areas on a site. Whole # s = FT Ex: is 1-0 higher than Decimal equivalent of FT = inches Ex: 99.5 is 6 (1/2 ft) lower than project benchmark (100.0) Focus on the relationship, not the numbers.

11 How Putting it all Together Contour line connects all points that are an equal vertical distance above or below benchmark

12 Grading and Drainage Basics Grading and drainage are often referred to as two sides of the same coin. When ever the shape of the land is altered, the movement of water is altered as well. Surface-drainage patterns fall into two categories: water collection and water dispersion (also called sheet flow); most sites incorporate elements of both. Water-collection strategies direct water toward a central collecting point. Sometimes this conveyance is achieved in the form of a swale (a depression in the landscape similar to a small stream channel in form, though much more shallow, and in many instances, nearly invisible). Water also may be directed into a drainage structure, such as a catch basin or drain inlet, that feeds water into an underground pipe. Often, a site will incorporate elements of above-ground and below-ground systems, taking advantage of the positive aspects of each. Grading and Drainage Principles Install erosion control measures before construction begins. Preserve existing grades around trees. Drain water away from house or structure Avoid draining onto adjacent properties Drain water away from high use or traffic areas Think about where you re draining water to

13 How Putting it all Together Pitch or slope to drain water over hardscapes, through planted areas, away from structures Rise = Vertical difference between points Run = Horizontal distance the vertical difference occurs in Rise divided by Run = % Slope 1 /8-1% = 1/8 /ft ie, 1/8 vertical elevation change/each ft. horizontal distance 1 /4-2% = ¼ /ft 1 /2-4% = ½ /ft etc. etc. etc.

14 Case Study Before Photos

15 Case Study Grading Plan

16 Case Study After Photos

17 As you chart The Scary World of Grading & Drainage remember Once you re in over your head, it doesn t really matter what the depth of the water is!! Acknowledgements Scott Byron & Co., Inc. Norman K. Booth Basic Elements of Landscape Architectural Design Rob Thallon & Stan Jones Graphic Guide to Site Construction