Specifying Soils for Complex Landscapespresentation outline

Pine&SwallowENVIRONMENTAL

Soil Design Strategies • Natural vs Blended • Simple vs Complex

Specifying Blended Soils • components • mix ratios vs use • specification controls

Teardrop Park • horticultural strategy • specifications

Robert Pine, PE, MLA, ASLA

Blended Soils

Specifying Soils for Complex Landscapes

Natural

Pine&Swallow

“Loam” Dealer

Limited Resource Mix of whatever came in that day

Controlled performance, Sustainable

Soil Design Strategies Natural vs Blended

Simple vs Complex Landscapes

Specifying Soils for Complex Landscapes Pine&Swallow

Soil Design Strategies Natural vs Blended

Tanglewood Teardrop Park

Base Loam

Blended Soil

CompostCompost

SandSand

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Blended Soils Components

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Blended Soils Components

Provides • silt and clay particles • stable organics • cation exchange capacity • natural soil biology

As percentage in a blend increases

• nutrient and water holding capacities ↑

• infiltration rate and aeration ↓

• resistance to compaction ↓

Note: Good quality topsoil is required for appropriate gradation, organics and soil biology.

Natural Topsoil

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Blended Soils Components

Provides

• structure • macropore space

As percentage in a blend increases

• aeration ↑ • infiltration rate ↑ • resistance to compaction ↑ • water holding capacity ↓ • nutrient holding capacity ↓

Note: Well graded sand reduces aeration, infiltration and resistance to compaction!

Uniform Coarse Sand

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Blended Soils Components

Provides • organic content • micro-organisms

As percentage in a blend increases

• water holding capacity ↑ • soil biology ↑ • resistance to compaction ↑ • resistance to anaerobic conditions ↓

Note: Immature compost creates bad soil biology and increased vulnerability to anaerobic conditions.

Mature Compost

Specifying Soils for Complex Landscapes Pine&Swallow

• Estimated Mix Ratio for each soil

• Grain Size Distribution

• Coefficient of Uniformity

• Organic Content

• Horticultural Requirements (CEC, pH,

nutrients, etc.)

• Compaction Range

• Saturated Hydraulic Conductivity at

maximum compaction

Primary Mix Design Specifications

Purpose

• define the soil blend • control soil properties

Specifying Blended Soils Specification Controls

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Blended Soils Specification Controls

• Testing and confirmation of base

materials: sand, loam, compost

• Testing to confirm mix ratios

• Batch production and testing prior

to delivery for quality control

• Handling and Placement procedures

• Control of wet soils

Primary Process Specifications

• Ensure quality control• Protect soil quality

Purpose

Teardrop Park Horticultural Strategy

Specifying Soils for Complex Landscapes Pine&Swallow

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements

• Withstand heavy use • High infiltration rate

High Use Turf

Specifications

Mix Ratio * 3S : 1.5L : 1C

% passing 270 sieve 11 -14%

Uniformity ratio D70/D20 < 4.5

Organic content 4 - 5%

Compaction 86 - 88%

Hydraulic conductivity > 4 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements

• Withstand moderate use

• Moderate infiltration rate • Reduced water requirements

Passive Use Lawn(not used at Teardrop Park)

Specifications

Mix Ratio * 2S : 1.5L : 1C

% passing 270 sieve 15 - 18%

Uniformity ratio D70/D20 < 5.0

Organic content 4 - 6%

Compaction 84 - 86%

Hydraulic conductivity > 3 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • rooting zone for trees / shrubs • free draining • not vulnerable to anaerobics

Horticultural Subsoil

Specifications

Mix Ratio * 2S : 1L

% passing 270 sieve 14 - 18%

Uniformity ratio D70/D20 < 6.0

Organic content 2 - 3%

Compaction 82 - 85%

Hydraulic conductivity > 2 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • recreate natural forest soil profile • encouraging shallow feeder roots • deep rooting in horticultural subsoil

Trees with understory no ground cover

Specifications

Mix Ratio * 2S : 1L : 3C

% passing 270 sieve 11 - 16%

Uniformity ratio D70/D20 < 6.0

Organic content 9 - 11%

Compaction 84 - 86%

Hydraulic conductivity > 3 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • recreate natural forest soil profile • suitable for ground cover plants

Trees with understory with ground cover

Specifications

Mix Ratio * 2S : 1L : 2C

% passing 270 sieve 11 - 16%

Uniformity ratio D70/D20 < 6.0

Organic content 6 - 9%

Compaction 86 - 88%

Hydraulic conductivity > 3 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • saturated conditions • support wetland plantings • high water holding capacity

Marsh Planting Soil

Specifications

Mix Ratio * 1S : 2C

% passing 270 sieve 8 - 12%

Uniformity ratio D70/D20 < 4.5

Organic content 10 - 12%

Compaction 82 - 85%

Hydraulic conductivity > 4 inches/hr

Note: Medium Sand not Coarse

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • structural support for heavy boulders • horticultural support for plantings

Boulder Base Mix

Specifications

Mix Ratio:

1 part 1.5 to 2 inch crushed stone1 part tree soil mix

Placed beneath heavy bouldersand compacted thoroughly

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • provide long term stability • protection from erosion • tree horticultural support

Steep slopes

Specifications

Mix Ratio:

2 to 4 oz fibers per cubic footthoroughly mixed withplanting soil

Placed and compacted to normal compaction range for specified planting medium

Specifying Soils for Complex Landscapes Pine&Swallow

Teardrop Park Specifications

Soil Requirements: • provide tree rooting volume • provide support for pavement • prevent settlements

Trees in paved areas

Specifications

Mix Ratio * 4S : 1L : 1C

% passing 270 sieve 7 - 9%

Uniformity ratio D70/D20 < 3

Organic content 2 - 3%

Compaction 92 - 94%

Hydraulic conductivity > 6 inches/hr

* S = Sand L = Base Loam C = Compost

Specifying Soils for Complex Landscapesrecap

Pine&SwallowENVIRONMENTAL

Soil Design Strategies • Natural vs Blended • Simple vs Complex

Specifying Blended Soils • components • mix ratios vs use • specification controls

Teardrop Park • horticultural strategy • specifications

Robert Pine, PE, ASLA