Following is the 2004 revision of the USGA Recommendations for a Method of Putting Green Construction.

For more than 40 years the USGA recommendations for green construction have been the most widely used method of green construction throughout the United States and in other parts of the world.

When built and maintained properly, USGA greens have provided consistently good results for golf courses over a period of many years. These guidelines are periodically reviewed and updated as a result of scientific research and as new techniques and materials are proven reliable. The remainder of this document specifically represents the USGA Green Section's recommendations for green construction. This document does not attempt to discuss various construction techniques or methods. Additional documents are available from the USGA that depict construction methods, offering tips for success and providing guidance for green management.

Step 1.

The Subgrade

The slope of the subgrade should conform to the general slope of the finished grade. The subgrade should be established approximately 16 inches (400 mm) below the proposed surface grade - 18 to 20 inches (450 to 500 mm) when an intermediate layer is necessary - and should be thoroughly compacted to prevent further settling. Water collecting depressions should be avoided. If the subsoil is unstable, such as with an expanding clay, sand, or muck soil, geotextile fabrics may be used as a barrier between the subsoil and the gravel blanket. Install the fabric as outlined in the USGA publication, Building the USGA Green: Tips for Success.

Construct collar areas around the green to the same standards as the putting surface itself.

Step 2 - Drainage

A subsurface drainage system is required in USGA greens. The pattern of drainage pipes should be designed so that the main drain(s) is placed along the line of maximum fall, and laterals are installed at an angle across the slope of the subgrade, allowing a natural fall to the main. Lateral drains shall be spaced not more than 15 feet (5 m) apart and extended to the perimeter of the green. Laterals should also be placed in water-collecting depressions if they exist. At the low end of the gradient, where the main drain exits the green, drainage pipe should be placed along the perimeter of the green, extending to the ends of the first set of laterals. This will facilitate drainage of water that may accumulate at the low end of that drainage area. Drainage design considerations should be given to disposal of drainage waters away from play areas, and to the laws regulating drainage water disposal. Drainage pipe shall be perforated plastic, minimally conforming to ASTM 2729 or ASTM F 405, with a minimum diameter of 4 inches (100 mm).

Waffle drains or any tubing encased in geotextile sleeves are not recommended. Drainage trenches minimally 6 inches (150 mm) wide and 8 inches (200 mm) deep shall be cut into a thoroughly compacted subgrade so that drainage pipes maintain a consistent slope to the outlet of at least 0.5%. Spoil from the trenches should be removed from the subgrade cavity, and the floor of the trench should be smooth and clean. If a geotextile fabric is to be used as a barrier between unstable subsoil and the gravel drainage blanket, it should be installed at this time. Under no circumstances should the fabric cover the drainage pipes or trenches. A layer of gravel (see Step 3 for size recommendations) should be placed in the trench to a minimum depth of 1 inch (25 mm).

It may be deeper, as necessary, to ensure minimal slope requirements. All drainage pipes should be placed on the gravel bed in the trench. PVC drainpipe, if used, should be placed in the trench with the holes facing down. Pipe connections shall not impair the overall function of the pipeline. The trenches should then be backfilled with additional gravel, taking care not to displace any of the drainage pipes. As an alternative to round pipe placed in a trench, flat pipe placed directly on the prepared subgrade may be employed, provided the flat pipe conforms to ASTM D 7001 (provisional), is a minimum of 12 inches (300 mm) in width, and is not covered by a geotextile sleeve. The flat pipe shall be stapled to the subgrade, or otherwise held in place to prevent shifting during construction. Rational combinations of round and flat pipe may be employed within a greens drainage system. All other guidelines for drainage system installation shall apply for this alternative construction method.

Step 3 - Gravel and Intermediate

Layers Place grade stakes at frequent intervals over the subgrade and mark them for the gravel drainage blanket layer, intermediate layer (if included), and root zone layer. The entire subgrade then shall be covered with a layer of clean, washed, crushed stone or pea gravel to a minimum thickness of four inches (100 mm), conforming to the proposed final surface grade to a tolerance of ±l inch. Soft limestones, sandstones, or shales are not acceptable. Questionable materials should be tested for weathering stability using the sulfate soundness test (ASTM C-88). A loss of material greater than a 12% by weight is unacceptable. The LA Abrasion test (ASTM C-131) should be performed on any materials suspected of having insufficient mechanical stability to withstand ordinary construction traffic. The value obtained using this procedure should not exceed 40. Soil engineering laboratories can provide this information. The need for an intermediate layer is based on the particle size distribution of the root zone mix relative to that of the gravel. When properly sized gravel (see Table 1) is available, the intermediate layer is not necessary. If the properly sized gravel cannot be found, an intermediate layer must be used.

Table 1

PARTICLE SIZE DESCRIPTION OF GRAVEL AND INTERMEDIATE LAYER MATERIALS

Table 2

SIZE RECOMMENDATIONS FOR GRAVEL WHEN INTERMEDIATE LAYER IS NOT USED

A. Selection and Placement of Materials When the Intermediate Layer Is Used

Table 1 describes the particle size requirements of the gravel and the intermediate layer material when the intermediate layer is required.

The intermediate layer shall be spread to a uniform thickness of two to four inches (50 to 100 mm) over the gravel drainage blanket (e.g., if a 3-inch depth is selected, the material shall be kept at that depth across the entire area), and the surface shall conform to the contours of the proposed finished grade.

B. Selection of Gravel When the Intermediate Layer Is Not Used

If an appropriate gravel can be identified (see Table 2), the intermediate layer need not be included in the construction of the green. In some instances, this can save a considerable amount of time and money.

Selection of this gravel is based on the particle size distribution of the root zone material. The architect and/or construction superintendent must work closely with the soil testing laboratory in selecting the appropriate gravel. Either of the following two methods may be used:

Send samples of different gravel materials to the lab when submitting samples of components for the root zone mix. As a general guideline, look for gravel in the 2 mm to 9.5 mm range. The lab first will determine the best root zone mix, and then will test the gravel samples to determine if any meet the guidelines outlined below.

Submit samples of the components for the root zone mix, and ask the laboratory to provide a description, based on the root zone mix tests, of the particle size distribution required of the gravel. Use the description to locate one or more appropriate gravel materials, and submit them to the laboratory for confirmation.

Gravel meeting the criteria below will not require the intermediate layer. It is not necessary to understand the details of these recommendations; the key is to work closely with the soil testing laboratory in selecting the gravel. Strict adherence to these criteria is imperative; failure to follow these guidelines could result in greens failure.

The criteria are based on engineering principles which rely on the largest 15% of the root zone particles "bridging" with the smallest 15% of the gravel particles. Smaller voids are produced, and they prevent migration of root zone particles into the gravel yet maintain adequate permeability. The D85 (root zone) is defined as the particle diameter below which 85% of the soil particles (by weight) are smaller. The D15 (gravel) is defined as the particle diameter below which 15% of the gravel particles (by weight) are smaller.

• For bridging to occur, the D15 (gravel) must be less than or equal to eight times the D85 (root zone).
• To maintain adequate permeability across the root zone/gravel interface, the D15 (gravel) shall be greater than or equal to five times the D15 (root zone).
• The gravel shall have a uniformity coefficient (Gravel D90/Gravel D15) of less than or equal to 3.0.

•  

  Furthermore, any gravel selected shall have 100% passing a 1/2" (12 mm) sieve and not more than 10% passing a No. 10 (2 mm) sieve, including not more than 5% passing a No. 18 (1 mm) sieve.