Amendment 0001 Q and A 140P8420Q0090_0001.docx

140P8420Q0090, Amendment 0001 Supply & Deliver ¾” Class II Aggregate Whiskeytown National Recreation Area

Question: I noticed in the rock specifications that Limestone was specifically not requested as a source. Just curious as to why? I've talked to some suppliers in the area that have lots of 3/4" Limestone base that meets all of the required DOT specifications, and was hoping the NPS may reconsider allowing Limestone.

Question: SGS is currently working on this solicitation and would like clarification as to why it has a requirement of rock free from limestone?

Our research shows that there is limestone in much of the current rock throughout the park. For example, the concrete boat ramp that goes right into the lake has cement made from limestone. Also, many of the bridges, dams, and Glory Hole has some kind of limestone. Another example is, the asphalt could be lime treated and could have limestone gravel Lastly, a couple of weeks ago in Clear Creek Park along Highway 299, used Limestone Rip Rap. If PH is an issue, industry standards prove the limestone helps balance PH levels. With these examples given, will "rock free from limestone" still be a requirement?

Answer: Yes, limestone free is a requirement. Limestone had been excluded for Park Roads for nearly 20 years. The reasoning behind exclusion of limestone is that the limestone weathers to form alkaline solutions (as opposed to the native rock) which change the chemistry of the streams, ultimately degrading habitat. Whiskeytown's stream waters are slightly acidic and poorly buffered, and consequently introducing limestone into environment alters the natural pH of the streams.

Adding limestone as a road base is different from constructing dams and boat launches. Applying crushed limestone to the roads provides a aggregate with a high surface area to volume ratio, which in turn increase weathering. In the case of a road, as more and more vehicles traverse the crushed aggregate, it continues to be crushed making smaller particles, increasing the surface area to volume ratio, and further increasing weathering and delivery to the streams. This is opposed to a dam (Whiskeytown Dam is an earthen, not a concrete dam) or boat launch, for example, where the surface area to volume ration is much smaller, resisting weathering and the surfaces are smooth and used much less frequently. Additionally, boat launches and dams are not solid limestone, but rather a mixture of aggregate bound with calcium carbonate derived from limestone, so a medium to small percentage (depending upon mix) is limestone. The aggregate also increases its resistance to weathering and erosion.