Boggs Mountain Demonstration State Forest Draft ... - Cal Fire

Boggs Mountain Demonstration State Forest Draft Management Plan, June 2008
Ripping is performed at all fill sites (including where outsloping occurs) prior to the application of
fill, and to all road and landing surfaces whether they are to be cross road drained or outsloped.
Road and landing surfaces should be ripped before any other treatment is applied. The ripping
depth and the maximum spacing between adjacent ripper shank passes shall average 1.5 feet
and spacing shall not exceed 2.0 feet.
Inboard ditches are not to be ripped where cross road drains are prescribed, nor are the
remaining benches ripped along reaches where Exported Outsloping (EOS) is to be performed. In
addition, the surface of stream crossing fills and other road fills, which are to be completely
excavated, need not be ripped if the fill is to be removed as a part of the rehabilitation treatment.
In some cases, decompaction of these surfaces may make later excavations easier to
accomplish.
2. Cross Road Drains (XRD)
A cross-road drain is a deeply cut ditch, excavated across a road surface, which drains the road
bed and inboard ditch. Cross road drains are more substantial and deeper than conventional
waterbars used to drain forest and ranch roads. Well constructed cross-road drains will often be
deep enough to prevent vehicular access to an area. Cross-road drains are typically constructed
(excavated) using a tractor, an hydraulic excavator or a backhoe.
Spacing of cross-road drains is highly dependent on the permeability and erodibility of the soil,
which is exposed on the road surface. Drains in stable, forested areas may be spaced
approximately 200 feet apart when road grades are less than 6%, and roughly 100 feet apart
when road grades exceed 6%. In areas of erodible, decomposed granitic soils, road surfaces
shall be drained at intervals not exceeding 50 feet and more frequently if local soil conditions and
road gradients dictate.
Each cross-road drain shall be free draining for its entire length, and have a uniform grade
approximately equivalent to the gradient of the ditch or adjacent road surface, which flows into the
cross-road drain. The depth of the drain at its inlet side should equal the existing inboard ditch
level, but shall never be less than 18 inches. In all cases, cross-road drains on ditched roads shall
be deep enough to intercept all ditch flow.
Spoil is placed, compacted and smoothed on the downhill side of the excavated drain as a berm.
Compacted fill and spoil is also used to completely fill the ditch at the drain inlet (where the drain
intercepts the inboard ditch) to prevent ditch flow from bypassing the structure’s inlet. Side-bank
steepness along the drain should not exceed 50%. Existing inboard ditches are left undisturbed
and free flowing to each drain.
No more than 15% of the total excavated volume of each cross-road drain may be sidecast at the
drain outlet (there is a tendency to sidecast more material when the drain is built by a tractor). In
areas underlain by decomposed granitic soils or other highly erodible soil, or where the drain is to
discharge in close proximity to a stream channel, sidecasting shall be avoided. This largely
dictates the use excavators and backhoes.
Cross-road drains shall not discharge onto the sideslopes of freshly excavated stream crossings,
or onto long reaches of bare, unprotected slopes. On a site-specific basis, energy dissipation
(rock armor, secured slash or other suitable materials) will be required to control erosion at the
outlet of the cross-road drain.
3. Waterbars
A waterbar is a shallow ditch excavated at an angle across a road or trail to drain surface runoff.
They are usually built on seasonal or temporary roads, which are to receive little or no traffic
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