HomeMy WebLinkAboutRWSA Water Supply ReportRevised Draft
Rivanna Water and
Sewer Authority
Recommended A 1 t e r n a t i v e s
Prepared by
~/Vanasse Hangen Brustlin, thC,
O'8den & Gem Engineers, lnc,
Ellis & Thorp, LLC
May, 2001
Vanasse Hangen Brusffm, Inc.
Revised Draft May 16, 2001
Table of Contents
List of Figures ...................................................................................................................... 111
Recommended Alternatives ............. ~ ................................................................................... 1
Introduction .................................................................. ,.; ...........................................................
Alternatives Recommended for immediate Implementation ...................................................... 1
1. Alternate Release at S. Fork Rivanna Reservoir ................................... 2
2. Water Conservation .............................................................................. 4
3. Drought Management ............................................................................ 5
4. Reduce Sediment Load into S. Fork Rivanna Reservoir ....................... 6
5. Four-foot Crest Controls ...................................................................... 10
Alternatives for Possible Future Implementation ..................................................................... 12
A. Improvements to Efficiency of Existing Water Resoumes .................................. 13
1. Dredging .............................................................................................. 13
2. Eight-foot Crest Controls ..................................................................... 16
3. Use SFRR as a Pumped Storage Reservoir ....................................... 17
4. Chris Greene Lake Drawdowns ........................................................... 17
5. Use Chris Greene Lake as a Pumped Storage Reservoir ................... 21
6. Use Beaver Creek to Supplement Flows in Mechums R ..................... 21
7. Dredge Sugar Hollow Reservoir .......................................................... 22
8. Conversion of Ragged Mountain to Pumped Storage ......................... 23
9. Indirect Reuse ..................................................................................... 24
10. Growth Management ......................................................................... 26
11. Leak Detection and Control ............................................................... 27
B. Physical
1.
2.
3.
4.
5.
6.
7.
Additions to the Existing Water Supply System ................................... 28
Groundwater ................................................................... ~ .................... 28
Reservoirs ........................................................................................... 29
James River W'~drawal at Scottsville ................... ~ ............................. 30
Rivanna River Withdrawal .................................... ~ .............................. 31
Mechums River Withdrawal ................................................................. 32
Regional Cooperation ........................................................................ 32
No-Action ............................................................................................. 33
Conclusions ............................................................................................................................. 34
Table of Contents
\~.V awil~p roject.~3OS0~R~ mmended Alternatives 4.doc
Vanass¢ Hangen Bmstlin, Inc.
Revised Draft May 16, 2001
Figures
figure No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Description Follows Page
Water Supply and'Demand .......................... : ............................................ 2
Summary of Water Needs ......................................................................... 2
Exceedance Curve for SFRR with Alt. Release ....................................... 3
Exceedance Curve for SFRR with Crest Control .................................... 12
Chris Greene Lake 5' Drawdown ............................................................ 20
Chris Greene Lake 10' Drawdown .......................................................... 20
Chris Greene Lake 15' Drawdown .......................................................... 20
Chris Greene Lake 20' Drawdown .......................................................... 20
Exceedance Curve for James R. Withdrawal ......................................... 30
Exceedance Curve for J. R. W.draw. plus Power Plant .......................... 30
Rivanna R. Schematic without Withdrawal ............................................. 31
Rivanna R. Schematic with Withdrawal .................................................. 31
Exceedance Curve for 4' Crest Control at Various Releases ............. :...35
Safe Yield for 4' Crest Control at Various Releases ............................... 35
Table of Contents
\\Vawill~j~rojectsk3~02~Wl~lREPOR~ _lm,c~n,3~___ AJlematives 4.do~
iii
Vanasse F~gen Brusfli~ Inc.
Revised Draft May 16, 2001
Recommended AlternatiVes
Introduction
The following recommendations result from analysis of raw water
supply and demand in the Urban Service Area, along with the
investigation of possible alternatives to address the identified water
supply deficit. In keeping with federal and state regulatory
requirements, the strategy proposed in this chapter attempts to meet the
short and long-term water demand in the least environmentally intrusive
manner, taking into account overall environmental effects, costs,
logistics, technical feasibility, and overall project purposes. In some
cases, these interests can be best served by implementing partial
solutions over time, delaying environmental disturbance and
maintaining the maximum amount of flexibility to deal with changing
conditions. The recommended strategy involves improvements to the
efficiency of existing water resources - no wholly new physical additions
to the system are being proposed.
Each of the alternatives discussed below is described in detail earher in
Analysis of Alternatives (Feb. 2000).. An executive summary of that
document, as well as summaries of the Supply Report and the Demand
Report ~ooth Oct. 1997) are included in the appendices. The following
sections provide supplemental information and propose an
implementation strategy.
Alternatives Recommended for
Immediate Implementation
The short-term need for additional raw water in the Urban Service area
is acute. The Summary of Water Needs presented in the Analysis of
Alternatives indicates that demand now exceeds safe yield in the Urban
Service Area. This means that during the next severe drought the
Rivanna Water and Sewer Authority will have insufficient water
supplies to meet demand. Furthermore, the demand and supply
projections are currently diverging at a rate of 3 million gallons per day.
(mgd) per decade, so that by 2010 the safe yield deficit will be
approximately 3 mgd (see Figure 1). Furthermore, diminishing supply is
Recommended Alternatives 1
~,Wawimp~O~'~.WtMIEl'Og~mm~ae~ .~enmiv~ 4.d~c
Vanasse Hangen Brustlin, inc.
Revised Draft May 16, 2001
an equal contr~utor to increasing demand in causing this divergence.
As such, even if demand were not to increase through 2050, the area
would face a water supply deficit of roughly 7 mgd (see Figure 2).
Accordingly, it is necessary to identify an alternative or alternatives
capable of meeting the current deficit, and' also able to provide adequate
supply throughout the 2050 planning period.
We recommend that the RWSA proceed to implement the following
alternatives to address the immediate and mid-term water deficit. In the
next section of this report, we will discuss other alternatives that may be
considered further and implemented, as needed, at some point in the
middle or later portions of the planning period.
1. Alternate Release Scenario at
S. Fork Rivanna Reservoir
Description of Alternative
When this study was begun, the study team was informed and
understood that SFRR was required as a regulatory matter to release at
least 8 mgd at all times. The safe yield of the reservoir was accordingly
calculated on that basis. Subsequent investigation has failed to identify
any such regulatory requirement, however. Accordingly, the current
yield of the reservoir is actually greater than that assumed in the supply
study. The difference amounts to 1.6 mgd, if the reservoir is assumed to
release at a rate of 8 mgd or at the rate of natural inflow to the reservoir,
whichever is less. In other words, when water flowing into SFRR
exceeds 8 mgd, a minimum of 8 mgd would be released; if inflow fails to
8 mgd or below, then the release would equal inflow.
Correcting the reservoir's stated yield in this way indicates that the
immediate, apparent water deficit identified by the Demand Analysis and
Supply Analysis can be satisfied in the very short term by the SFRR.
Furthermore, there would likely be no practical consequence to restating
the reservoir's yield in this way. The scenario would occur only on those
rare occasions when the water level falls below the top of the dam.
Anecdotal evidence suggests that this has happened only 2 or 3 times
since the dam was constructed in 1966. Furthermore, once a source of
additional supply is obtained, the RWSA could of course adopt or accept
a prescribed minimum release. Even if a severe drought should occur
before a new water source is brought on-line, the natural river flow
would simply be passed downstream without augmentation.
Recommended Alternatives
\\V aw~,o.a=c~O$ 02~.WI~POR~ mmead~ Alt.~'~a~ves &doc
22
2O
Water Supply and Demand
18
,-. 16
0
~ 14
V
~- 12
6
4
2
0
1970
1980 1990 2000 2010 2020
2030
2040
2O50
Year
Figure 1
22
20
18
16
14
12
10
8
6
4
2
0
1970
198O
1990
Summary of Water Needs
-
2000
2010 2020 2030 2040 2050
Year
Figure 2
' '~ vanasse Haag~n Bras*lin, Inc. Revised Draft May 16, 2001
Effectiveness
The revised release would provide 1.6 mgd in additional safe yield. It
could thus meet the needs of the Urban Service Area over the next 1-2
years, until a longer-term solution is available.
Practicability/Cost
The cost for this alternative is quite low at $386,000, for a unit cost of
$0.24/gallon. This accounts for installation of necessary gauges as well
as valving and controls at the SFRR dam. It may be possible to utilize
existing gauges, thereby lowering the total cost slightly - this potential
should be investigated.
Environmental
The revised release would actually be implemented only when a severe
drought occurs. At such times, the release from the reservoir would
equal the inflow to the reservoir. In other words, strearnflows would be
at their natural levels during such droughts, rather than being
augmented from reservoir storage. The temporary nature of the revised
release, combined with the infrequency of its use (only during rare and
severe droughts), minimizes the impact to downstream flow. Figure 3
shows the flow exceedance curves for the South Fork Rivarma River
downstream of the dam, with and without this alternative. The curves
demonstrate the percentage of the time that flows exceed a given level.
As shown, the "w/o Project" line ends at 8 mgd, reflecting the
previously assumed required release, while the "w/ Alternate Reservoir
Release" line drops below 8 mgd. Except for the very highest
percentages, the flows are similar; for instance, river flows without the
project exceed 20 mgd roughly 93% of the time. With the project, river
flows exceed 20 mgd roughly 91% of the time. Furthermore, with the
project, flows drop below 8 mgd less than 1% of the time.
During design of the valving system, the potential for mixing surface
and bottom water, to optimize temperature and oxygen levels, should be
investigated.
Recommendation
Although designated as an "alternative" in this report,'restating the yield
of SFRR really amounts to correcting the yield stated in our original
Supply Analysis to reflect the absence of the previously-assumed 8 mgd
constant release, and an assumption that RWSA nevertheless would
voluntarily commit to release either 8 mgd or natural inflow, whichever
is less. We recommend this alternative be selected at least as a temporary
measure, until another alternative is available to meet longer-term
demand. It is one of the very few measures that could be implemented
and meet system demand if a drought were to occur in the immediate
Reconunended Alternatives
'~VawiL~project.~0502'~RTS'~Re~mnw. nded AJtemafives 4.doc
Flow Exceedance Curve for South Fork Rivanna Reservoir Downstream of Dam
Downstream Flow (mgd) Period of Record: Oct. 1,1929-Sept.30, 1999
100
90
80
70
60
50
40
30
20
10
0
Exceedance Percentage
+ w/o Projects (Existing Conditions)
-+- w/ Alternate Reservoir Release
Figure 3
Vanasse Hangen Brustlin, Inc.
Revised Draft May 16, 2001
short-term. Furthermore, the only environmental effect would-be a
temporary return to natural streamflow conditions downstream from the
dam during severe droughts.
2. Water Conservation
Description of Alternative
This alternative consists of immediate development and implementation
of a water conservation plan for the Urban Service Area. The resulting
water conservation can be monitored, and its effectiveness documented
and assessed over time. The safe yield benefit suggested herein is based
on evidence from other programs, but it is possible that greater savings
(or lesser) could be achieved, thereby postponing (or hastening) the need
for longer-term measures outlined below. Implementation of this
alternative would consist of developing a plan to take advantage of
water savings resulting from a variety of measures, including plumbing
fixture changeout, public education, industrial conservation, and
conservation pricing.
Effectiveness
The Analysis of Alternatives concludes that voluntary conservation
measures can reduce demand in 2050 by approximately 1.7 mgd (8% of
2050 total demand). Because a variety of-factors will affect the program's
success, an exact figure cannot be calculated. The effectiveness of this
alternative should be monitored over time, so that the long-term benefit
can be estimated. It is important to realize that the 1.7 mgd is based on
2050 water demand; benefits will be proportionately less in the short
term.
Since publication of the Analysis of Alternatives,'additional case studies of
conservation have been analyzed. The results highlight the variable
results of different programs, and underscore the need to implement and
monitor conservation over time.
According to the Water Resources Department in Asheville, North
Carolina, the drought in 1998-1999 resulted in a phased plan' that
included voluntary conservation as well as mandatory restrictions
(treated as Drought Management in this report). The cumulative
impact of those conservation and drought management efforts was a
25% short-term reduction in commercial/industrial/institutional
usage and a 14% short-term reduction in residential usage (City of
Asheville web page, 8/23/00). The Analysis of Alternatives treats
voluntary conservation and mandatory restrictions as distinct
alternatives, and suggests that their cumulative impact is 4.1 mgd
(1.7 from conservation and 2.4 from drought management), or
roughly 21% of total 2050 demand.
Recommended Alternatives
~Vawill~pr ojects~ 0502~Wi~REPORTS~--o mmended. Al~.na~ive~ &doc
Vanasse Hangen Bmst~ Inc.
Revised Draft May 16, 2001
The City of GreenSboro, North Carolina, implemented a voluntary
drought management program in 1994. In 1998-1999, in response to
drought conditions, the City used increased publicity and other
elements to encourage additional short-term reductions in demand.
The City used 20% less water in December 1998 than December 1997
(City of Greensboro web page 8/23/00).
In 1991, the Irvine Ranch Water District in southern California
implemented a conservation program that includes water budgeting
(with price incentives), education, and installation of low-flow
plumbing fixtures. Between 1991 and 1998, residential water use
dropped by 13% (New Mexico Water Conservation Alliance, spring
1999).
PracticabilitylCost
The cost for this alternative is estimated to be $2.5 million, excluding any
potential reduction in revenues due to lower sales. This amounts to an
overall unit cost of $19.23/gallon. However, the cost is attributable to
the public education component, while most of the yield is attributable
to plumbing changeout. This suggests the public education component
may not be cost-effective.
Environmental
No negative environmental effects of water conservation were identified.
Recommendation
Water conservation measures can reduce demand and some measures
can be cost-effective. Accordingly, we recommend immediate
development and implementation of a water conservation plan and
efforts to monitor its effectiveness over time. If measures should prove
more successful than our investigation has assumed, that would make it
possible to delay implementation of other, longer-term alternatives.
Conversely, if water conservation techniques are less effective than our
projections, subsequent components of a long-term water supply
solution could be accelerated. This eventuality may also necessitate
reevaluation and.modification of the conservation program.
3. Drought Management
Description of Alternative
Drought management techniques consist .of various voluntary, and
mandatory measures to reduce water use during drought conditions.
Recommended Alternatives 5
~Vawillkpro~C~OS02~Wl~KE PORT~XReco mmended Allernattves &doc
'~ Vanasse Hangen Brustlin, Inc. Revised Draft May 16, 2001
These techniques 'are explained in greater detail in the Analysis of
Alternatives. The City of Charlottesville and Albemarle County both
adopted drought management ordinances during the summer of 2000.
Effectiveness
It is estimated that these measures could provide the equivalent of 2.4
mgd of supply during a drought in 2050. As with conservation, the
short-term benefit would be less, and the effectiveness of the program
should be monitored over time.
Practicability/Cost
This alternative is actually comprised of two measures - demand side
and supply side management. The cost for demand side drought
management is $250,000, for a unit. cost of $0.18/gallon - very low.
Supply side measures involve modifications to system operations and
procedures and the related costs would be difficult or impossible to
quantify. However, any such costs are assumed to be reasonable.
Environmental
No negative environmental effects of drought management were
identified, apart from loss of vegetation that may result from restrictions
on outdoor water use (lawn watering) during droughts.
Recommendation
Drought management techniques provide a practicable, cost-effective
and environmentally sound means of extending existing water supplies.
Accordingly, we recommend immediate development and
implementation of a drought management plan, including means to
assess its effectiveness over time.
4. Reduce Sediment Load into S.
Fork'Rivanna Reservoir
Description of Alternative
To date, Albemarle County has utilized an array of techniques to reduce
sedimentation in the SFRR watershed. These include: zoning
regulations, construction of stormwater best management practices
(BMPs), riparian buffer requirements, erosion and sediment control
regulations, voluntary agricultural cost share programs, and forestry
BMPs. It is possible that these efforts have prevented the rate of
Recommended Alternatives
6
\\Vawill~ro~-IS~05OLW~¥PkREPOR~o nmaandmt Al~-natave~ &doc
- ~ Yanassc I-inagen Brustlin, Inc. Revised Draft May 16, 2001
sedimentation ~rom increasing over time (the actual rate has been less
than originally predicted prior to construction of the reservoir). Their
actual effect is impossible to quantify at present.
The Analysis of Alternatives provides a timeline of watershed
management initiatives: The County's current program results from the
1998 enactment of the Water Protection Ordinance. According to the
Albemarle County Departa~ent of Engineering & Public Works, the
methods used to control sedimentation in the County are as follows:
"Upland BMPs
Stormwater treatment via BMP is required for ail new
development; BMPs are discussed in the Interim Design
Manual. Though the County's keystone pollutant is
phosphorus, BMPs normally capture sediment in an effort to
remove bound phosphate. Multipliers in the procedure .for
calculating the phosphorus removal requirement lead to higher
'removal requirements in the water supply watersheds than in
other areas.
Stream Buffers
Stream buffers are a special case of BMP. Stream buffers are
required in Albemarle County Code using the Virginia
Chesapeake Bay Preservation Act as the enabling legislation.
In the SFRR watershed, buffers are required around both
perennial and intermittent streams (as delineated by County
stafj9 on all development sites. This program is most
forcefully applied to new development. Buffers on previously
developed sites are addressed through education and
enforcement of violations. Twenty five feet buffers and
conservation plans are required on cropland bordering
perennial streams. For pasture land, County and Soil and
Water Conservation District staff feel that the Agricultural
Stewardship Act is a more effective way to correct "bad actor"
situations. For forestry practices, the County's ordinance
exempts silvicultural operations as long as forestry BMPs are
followed. There is also a state law, administered by the
Department of Forestzy, which addresses "bad actor" cases.
Erosion and Sediment Control
The County's Erosion and Sediment Control (E&S) program
regulates active development sites. This program is required
by state law and overseen by the Department of Conservation
and Recreation. The E&S program is staffed by three field
inspectors, two plan reviewers, and one supervising engineer.
The program is applied to the entire County. Because the
SFRR watershed is roughly one-third of the County and there
are six staff members in the program, the equivalent of two
staffers are available for SFRR E&S review and enforcement.'
(Quoted from memo of May 15, 2000)
This comprehensive approach to sediment control, the high percentage
of forest cover in the watershed (73%), and the continuing rate of
sedimentation raise the possibility that the SFRR is receiving natural
Recommended Alternatives 7
\'~Vawill~ro~-Is~0502~Wl~REPORTS~Recommead~d A.ltmnati~ 4.doc
Vanasse I-Iangen Brusflin, Inc.
Revised Draft May 16, 2001
amounts of sedimentation from its large watershed. Furthermore, it is
possible that most of the sediment delivery to the SFRR occurs during
rare large storms. Given these factors, significant reductions in sediment
input to the reservoir could prove extremely difficult.
As originally described, this alternative consisted of constructing
additional regional stormwater management ponds (similar to the
Lickinghole Creek BMP) and modification to the County's riparian
buffer policy. A number of factors have resulted in changes to this
strategy.
First, the regulatory agencies have made it clear that in-stream
stormwater management ponds have significant negative environmental
effects and are not a preferred alternative. The BMP focus has therefore
shifted to forebays at the headwaters of the SFRR. Forebays are similar
to stormwater ponds, but they would be constructed munediately
upstream of the reservoir. Forebays are generally shallow, wide, and
naturally vegetated; they would trap sediment at the head of the
reservoir, concentrating the material in a contained area from where it
could be p~riodically dredged. Like other BMPs, they can only remove a
certain percentage of sediment, and they require periodic mainten__ance in
the form o~ dredging.
Second, the prevalence of forested buffers throughout the watershed and
the County s active buffer program have mdtcated that overland flow m
one contributor (but not the major contributor) to reservoir
sedimentation. It appears possible that stream bank erosion is a more
ennant~actor, and this alternative therefore indudes~est~gation'Of
oten.ti~l for targeted stream,r_estoration. However, itmay also prove
possible to enhance Albemarle s buffer program, and this alternative
retains the need to investigate this possibility.
Because the potential effectiveness of reducing sediment inputs to the S.
f0~'~ebay construction,
Effectiveness
The dynamics of sediment transport and capture make the effectiveness
of these measures impossible to quantify at present. Nevertheless, it
appears plausible that past efforts have prevented an increase in the rate
of sedimentation over time, and that future efforts could accomplish a
similar objective.
Forebays
Construction of forebays has the potential to reduce, but. not eliminate,
sedimentation into the SFRR. Like upstream stormwater management
ponds, ind~viduaI forebays are estimated to have a 40% sediment
removal efficiency. It is important to emphasize, however, that it would
Recommended Alternatives
\\Vawil~proje~s~3OS02~WP~gEl~RTSW. eco mmended Alternatives 4.doc
~ Yanasse Hangen Brustr~ Inc. Re~,ised Draft May 16' 2001
prove impossible to treat the entire volume of water entering the
reservoir, and that the bulk of sedimentation may well occur during
dramatic storm events. The above efficiency, therefore does not imply
that forebays could reduce the total sediment load into the reservoir by
40%. Furthermore, the large size of the watershed is a contributing
factor, and could diminish the overall effectiveness of forebays.
Stream Restoration
It is possible that identifiable segments of eroding stream banks are
contributing a significant portion of the sediment 10ad, particularly
during large storm events. Restoration of erosion' hot spots has the
potential to reduce the overall loading into the reservoir. Natural
erosion is one issue that warrants careful analysis here; based on
hydrologic and geologic conditions, streams will carry a certain amount
of sediment. Stream bank restoration in one area could possibly result in
creation of an erosion problem downstream, as the stream attempts to
pick up its natural sediment load.
Practicability/Cost
Forebays
The cost of forebay construction would depend on the actual locations
-and sizes of the facilities, and a detailed analysis would be necessary to
determine the most cost-effective approach to construction. This
discussion assumes construction of 2 forebays - one at the head of the
reservoir below the confluence of the Mechums, Moorman'~, and Buck
Mountain Creek, and one where Ivy Creek enters the reservoir. The total
estimated cost to design and construct the forebays, is $232,000. Clean
out maintenance could occur periodically, every 2-3 years; costs for these
activities equates to an annual cost of roughly $46,000, Because no safe
yield can be assigned reliably to this alternative, no unit cost can be
calculated.
Stream Restoration
Given the number of possible locations and various scales of possible
restoration sites, as well as the inability to quantify their potential
effectiveness, no costs were assigned to this option.
Environmental
Forebays.
The impact of constructing sediment forebays would depend on the
exact location, size, and design of the facilities. Possible effects include
the loss of wetlands, but the extent of that impact would depend on the
variable factors described above. No cost for wetland mitigation was
included; however, depending on specific location, mitigation may be
required.
Recommended AlternatiVes
9
\\Vawil.hprolects~30502~WP'dl.EPOR~ mmcnded Almmatives 4.doc
~ Vanasse Hangcn Brustli~ Inc. Revised Draft May 16, 2001
Stream Restoration
As part of a stream classification effort, restoration could have a positive
impact, by addressing erosion hotspots.
Recommendation
All practical efforts to-reduce sediment inputs to S. Fork Rivanna
Reservoir should continue, as they might prolong the useful life of the
reservoir and obviate future dredging. Accordingly, we recommend this
alternative be pursued immediately as a supportive measure, and that its
effects be monitored. We also recommend that additional measures, such
as stream bank restoration, construction of reservoir forebays, and an
enhanced riparian buffer program should be investigated further, even
though their effectiveness cannot be quantified at this time. Additional
studies (for instance to assess the potential for stream bank restoration)
and periodic bathymetric surveys would help to determine whether the
strong sediment control program currently in place could effectively be
enhanced.
5. Four-foot Crest Controls
Description of Alternative
This alternative would involve installation of an inflatable bta~ider on the
SFRR dam, in order to increase the reservoir pool height by 4', thereby
adding storage capacity to the reservoir. A similar bladder was recently
installed on the Sugar Hollow dam. Previous dam stability analyses
indicated that the SFRR dam with 4' crest controls would comply with
Virginia dam safety regulations. This alternative will likely require some
land acquisition, although the exact amount is uncertain and will require
additional investigation. For the purposes of this analysis, it is assumed
that up to 100 acres would .be required. Also, replacement of the Route
676 bridge over Ivy Creek may be required. We have consulted with
VDOT but do' not yet have definitive information as to whether the
bridge must be replaced or how the associated costs might be allocated.
The raised pool level would impaq the location of any proposed
sediment forebays, and their exact location would require site specific
analysis.
Eflec~venes$
This alternative is estimated to provide approximately 35 years of
additional supply, based on current demand projections and
sedimentation rates. The crest controls would provide 7 mgd additional
safe yield in 2050. This safe yield figure accounts' for additional
sedimentation over time. The immediate increase in safe yield upon
completion would be approximately 11 mgd. If the rate of sedimentation
Recommended Alternatives 10
\\Vawill~projecc~3OSO2~Wl~.EPORTh3R~o~ Alumu~v~ 4.doc
~ Vanasse Hangen Bnm~ Inc. Revised Draft May 16, 2001
decreases, or if water conservation or drought management techniques
should prove more effective than we have estimated, then this
alternative may meet future water needs of the Urban Service Area for
an even longer period.
Practicability/Cost
This alternative has a relatively low base cost of $2.26 million, for a unit
cost of $0.32/gallon. It makes use of existing water treatment and
transmission facilities and extends the useful life of the existing S. Fork
Rivanna Reservoir. These cost figures assume no land purchase or
bridge replacement.
During the initial investigations into this alternative, it was assumed that
the City of Charlottesville owned property to an elevation of 387' -
adequate for the proposed 386' pool level. It now appears that this may
not be the case in all sections of the reservoir, particularly in the upper
reaches of the SFRIC Given the uncertainty of the extent of City
ownership, it appears likely that some property acquisition will be
required. Although the exact amount could only be determined by
extensive field surveys, we estimate the amount to be approximately 100
acres. This estimate is based on examination of topographic maps, as
well as anecdotal evidence. The number is subject to the limitations of
the topographic maps and their associated scale and topographic
interval. Nevertheless, we believe this to be a reasonable estimate of the
order of magnitude of the likely acreage. Using a land value of $13,000
per acre, this would increase the cost of the alternative by roughly $1.3
million. This per aCre figure is somewhat higher than the average land
value used for other alternatives, reflecting the potentially higher value
of property fronting on the reserVoir. Additional purchases of land for
flood easements would not in general be required, since the bladder
allows for control of the water, level, and would be deflated accordingly
in the event of a flood.
Should replacement of the Ivy Creek bridge be required, the cost of the
alternative would increase by approximately $2 million. The estimated
land purchase and the bridge replacement would therefore increase total
cost to roughly $5.6 million, for a unit cost of $0.80/gallon. These costs
are still relatively low in comparison to other alternatives.
This cost assumes mitigation for 5 acres of wetlands impacts, as
described below. However, it is possible that no mitigation or mitigation
for an additional 13 acres of reservoir perimeter wetlands could be
required. Accordingly, the cost of this alternative could vary from just
over $5 million to almost $7 million (including land and bridge costs).
Initial investigations into this alternative identified 2 potential residential
displacements, based on mapping analysis. Preliminary field
investigations have failed to identify these structures, and costs are not
included for their purchase. Furthermore, such structures would not be
expected significantlY to impact the total cost. Mapping analysis also
identified potential archaeological resource impacts that would require
Recommended Alternatives 11
\\Vawil i~mo~cU.k30502~,WiARE POR~ o mm~nd~ Alte~n~.ives 4.doc
~]~ vanassc Haa~¢n Brust~ Inc. lt~ised Draft May 16, 2001
further investigation. Again, this is not expected significantly to impact
total cost or feasibility.
Environmental
The Virginia Department of Game and Inland Fisheries conducted an
intensive mussel survey in the vicinity of and upstream of the proposed
pool level. Their written' analysis concludes that 4' crest controls would
have no impact on the James spinymussel.
Increasing the pool elevation of the reservoir by 4' would inundate
approximately 18 acres of wetlands. Approximately 13 acres of these are
wetlands that have developed spontaneously around the perimeter of
the existing reservoir; following establishment of the new pool elevation,
wetlands similar in nature and greater in extent (due to the larger
perimeter) would likely develop. Accordingly, this alternative would
have long-term impacts to approximately 5 acres of wetlands. These
impacts could be offset through appropriate mitigation.
If the regulatory process should require mitigation for the full 18 acres,
the cost of this alternative would increase, as discussed above.
Alternatively, it is possible that this alternative will not require a permit
and associated regulatory oversight, thereby lowering the mitigation
cost.
Figure 4 shows the flow exceedance curves with and without the project.
As can be seen, river flows without the project exceed 20 mgd roughly
93% of the time. With the project, river flows exceed 20 mgd roughly
89% of the time. With the project, flows do not fall below 8 mgd,
reflecting the proposed establishment of an 8 mgd constant minimum
release from SFRR.
Recommendation
We recommend that RWSA immediately pursue design and preparation
for installation of 4' crest controls. This alternative would provide
significant water supply into the middle of the planning period, is cost-
effective, and has limited environmental impacts that may be effectively
offset.
Alternatives for Possible Future
Implementation
The above alternatives would provide sufficient water supply to meet
immediate and mid-term needs. Nevertheless, demand through the 2050
planning period is expected to exceed the safe yield of the improvements
discussed above, necessitating additional supply.
Recommended Alternatives
\\Vawill~ol~ct~30502~Wl~REl~R~mmm~d~l Alletnalives 4.doc
12
Flow Exceedance Curve for South Fork Rivanna Reservoir Downstream of Dam
Downstream100 Flow (mgd) Period of Record: Oct.* ~pt.30 1999
9O
8O
7O
6O
5O
4o
3O
2O
10
0
Exceedance Percentage ~I-~*~- w/W/°crestPr°jeCtScontrol(EXisting Conditionsl
Figure 4
' ~ Ya~e Han~n Brustl~ ~c. Revised Draft May 16, 2001
Two alternatives - using Chris Greene Lake for water supply purposes
and dredging of SFRR - appear to offer the most promise, while others
appear not to be part of a practicable solution based on analysis to date
of effectiveness, costs, and environmental impacts. The following
sections assess and offer recommendations with respect to each of these
remaining alternatives.
A. Improvements to Efficiency of Existing.
Water Resources
1. Dredging
Description of Alternative
The dredging alternative consists of removing and disposing of some or
all of the accumulated sediment in the upper and middle reaches of the
SFRtL The reservoir is currently losing storage capacity due to siltation
at a rate of approximately 13 million gallons per year, and this
alternative includes two options for addressing this issue and increasing
the long-term safe yield of the reservoir.
The first option involves a one-time dredging event sometime prior to
2050. This action would return the reservoir to roughly its original
storage capacity; thereafter sedimentation would continue and yield
would diminish. The second option involves annual maintenance
dredging to maintain the current yield of the SFRR. Both options would
result in similar safe yield increases in 2050.
Effectiveness
In theory, dredging could be an effective means of restoring water
storage capacity and therefore yield to the SFRR. Dredging could be
structured to provide various safe yield increases (based on the volume
of material removed from the reservoir). As currently described, this
alternative would return or maintain the current safe yield of 7.2 mgd.
Practicability/Cost
Additional research performed concerning this alternative subsequent to
our prior evaluation has included contacting several additional dredging
contractors to solicit cost estimates. This investigation uncovered a wide
range of possible costs; the original estimate in the Alternatives
Evaluation is within that range.
Recommended Alternatives
\\V a~lg pro~.~OSO2~WP~w_.PORT ~R~:o m m~nd~d ~ 4.~3c
13
~ Vanasse Hangen Bmstlim Inc. Revised Draft May 16, 2001
To demonstrate the wide range of possible costs, two scenarios are
outlined here- both assume pumping dredged material to a site in the
immediate vicinity of the reservoir (approximately the same distance in
both cases). If the pumping distance were increased to the extent that an
intermediate pump station were required, the cost of both scenarios
would increase by $1.5 million. The first scenario assumes a one time
dredging event, around year 2020, with permanent disposal at an upland
site that requires a degree of construction to contain and dewater the
sediment. In order to achieve 7.2 mgd in safe yield, 3.07 million cubic
yards of sediment would need to be dredged (assuming siltation rates
remain constant). The total cost for such an event is approximately $40
million, as detailed below; amounting to a unit cost of $5.56/gallon. The
percentage costs £or fees and contingencies are included in the cost of all
alternatives - they are shown here as line items for clarity.
· Land purchase ......................................... $2 million
· Earthen dams .......................................... $2 million
· Dredging ~$7 per cubic yard ...................... $21.5 million
· Wetland mitigation .................................. $800,000
· Improvements to WTP .............................. $3 million
· SUBTOTAL ............................................ $29.3 million
· Eng., legal, admin, fees 15% ........................ $4.4 million
· Contingencies 20 Yo ................................... $5.9 m~lhon
· TOTAL .................................................. $39.6 million
This scenario uses an average value for dredging cost per cubic yard,
and assumes that a single upland site could be purchased and developed
for this purpose. As such, this represents the low end of the possible cost
range. The appropriate site would consist of roughly 180 acres, and
contain ravine topography with limited wetlands. Construction would
be limited to earthen dams at the head and foot of the spoil site, utili~.iug
steep slopes to contain the bulk of the material. Given the topography in
the vicinity of the reservoir, several such sites could be available.
A second scenario assumes that disposal options prove more restricted,
and that spoil material has to be dewatered at a temporary site and then
hauled to a permanent location. The following figures assume a 25-acre
drying site, on which 8' high earthen dikes are constructed to contain
sediment at a depth of 6'. Such a site would be capable of containing
approximately 240,000 cubic yards of sediment. Assuming 13 dredge
events over 8 years (allowing roughly six months dewatering time for
each event), the full 3 million cubic yards could be handled. The total
cost under these conditions is approximately $75 million, as detailed
below, for a unit cost of $10.42 / gallon.
· Land purchase ....................................... $275,000
· Dredge/dry/haul @ $17 per cubic yard ....... $52.2 million
· Improvements to WTP ............................. $3 million
· SUBTOTAL ........................................... $55.5 million
· Eng., legal, admin, fees 15% ...................... $8.3 million
· Contingencies 20% .......... ~ ....................... $11.1 million
· TOTAL ................................................. $74.9 million
Recommended Alternatives
\Wawill~pro~ts~3OSO2~Wl~REPOR~ommen~d Alta-naives &doc
14
~ Vanasse Hang~n Brustlin, Inc. Revised Draft May 16, 2001
This estimate is closer to the original amount detailed in the Alternatives
Analysis, and represents the upper end of the possible range. It should
be noted that the time factor associated with this option could
significantly increase its cost. In particular, if dredging equipment and
piping could not be stored on-site during drying periods, mobili~.ation
and start up costs could be prohibitive. Site characteristics in this option
include a relatively flat, upland site, requiring significant construction in
the form of earthen dikes. Although the land surrounding the reservoir
generally consists of rolling topography, several relatively level areas
along ridgetops could be available to meet the requirements of this
option.
Annual maintenance dredging, as described in the Alternatives
Evaluation, remains a possible solution. This option includes land
purchase of approximately $2.2 million, infrastructure costs of
approximately $5 million, and annual dredging, dewatering, and
disposal costs of $800,000. The total cost through 2050 would therefore
be roughly $47 million, or $6.53/gallon.
Each of these scenarios assumes that the spoil material must be disposed
of. If a beneficial use could be found for some or all of the material, costs
could be reduced accordingly. In fact, depending on the use, grant
handing may be available to assist with total cost. The amount of grant.
funding available could be very limited, however, and account for only a
small portion of total project cost. Furthermore, given the large amount
of material in question, finding beneficial uses for a substantial portion
could prove difficult.
Environmental
The dredging activity itself, including equipment access and staging,
would temporarily impact wetlands and shallow water h.abitat. In
addition, additional impacts to shallow water habitat are expected in
areas where accumulated sediment is removed. The first disposal
scenario is also likely to involve permanent wetland impacts, and
mitigation costs are factored in for impacts to approximately 9 acres;
Dredging would also temporarily resuspend bottom sediments and
organic detritus. Costs are included for temporary increases in water
treab,nent resulting from this disturbance.
Loss of upland farm land or wooded habitat would also result from this
alternative.
Recommendation
For now, we recommend that RWSA make every reasonable effort to
control sedimentation to the reservoir and conduct bathymetric surveys
every 5 years to monitor sedimentation rates over time. Actual rates of
siltation will help determine the need for, the scale of, and the timing of
Recommended Alternatives
15
\\¥awill~-ol~.c~30502~WP~01EPORT~R~ommende~. Allematn~ 4.d~c
~' ~ Vanasse Hangen Brustlin, Inc. Revised Draft May 16, 2001
dredging. This alternative offers the potential to increase safe yield over
the longer-term, but has a higher unit cost and greater environmental
impacts than the alternatives recommended herein for immediate
implementation.
2. Eight-foot Crest Controls
Description of Alternative
This alternative is similar to the 4' crest controls discussed above, but
would raise the reservoir pool level by 8'. This action would require
more extensive land purchases and would definitely require bridge
replacement.
Effectiveness
The 8' crest controls would provide 11 mgd in additional safe yield in
2050.
Practicability/Cost
At $18.3 million ($1.66/gallon), the cost for this alternative is moderate,
although it is significantly higher than the 4' option due in part to land
purchase and other costs associated with the higher water level.
Environmental
This alternative would impact approximately 39 acres of wetlands, of
which 13 have developed around the reservoir perimeter and' could be
expected to be replaced by wetlands forming at the new pool level.
Accordingly, the 8' crest controls involve permanent impacts to 26 acres
of wetlands. The cost analysis presumes that mitigation, would be
provided for these impacts.
Additional investigation would be necessary to assess the potential
impacts to the James spinymussel in Ivy Creek based on the higher pool
elevation.
Recommendation
This alternative provides significant safe yield to meet the water supply
needs of the Urban Service Area. However, it has a higher unit cost and
greater wetland impacts than the 4' version, as well as potential impacts
to the James spinymusseL Accordingly, this alternative is not
recommended as a component of the water supply solution at this time.
Recommended Alternatives
~VawilI~oroj=ctsk30502kWl~Rl~POR~omm~d~l AlI~nativ~ 4.doc
16
~ Vat. se Hang~n Bn~din, Inc. Revised Draft May 16, 2001
Use SFRR as a Pumped
Storage Reservoir
Description of Alternative
This alternative consists of withdrawing water from the Rivanna River
and pumping it to the SFRR. It includes construction of an intake and
pump station on the Rivanna River just downstream of the confluence of
the North and South Forks.
Effectiveness
Using SFRR as a pumped storage reservoir is not practical due to lack of
storage capacity in the lake during non-drought conditions and lack of
sufficient flow in the Rivanna River during those times when storage is
available. It would therefore provide no increase in safe yield.
Practicability/Cost
No costs were developed due to the impracticability of this alternative.
Environmental
This alternative would have minimal environmental impacts.
Recommendation
This alternative would provide no safe yield, and we do not recommend
that it be included as part of a practicable solution at this time.'
4. Chris Greene Lake
Drawdowns
Description of Alternative
This alternative involves use of water in Chris Greene Lake to
supplement the water supply system during periods of drought.- The
Analysis of Alternatives described two versions of this measure - a
drawdown of up to 5' and a drawdown of 20'. Supplemental
investigations have detailed the safe yield of 10' and 15' drawdowns,
and have identified the frequency at which each of these events would
occur. For all of these versions, water would be piped directly from the
lake to the North Fork water t:reatment plant in order to prevent pump
damage and maintenance problems that presently result from the intake
Recommended Alternatives 17
\~ Vawil hproj~cls'~0~Y2n, WI:'~EPOR~o mm~ d~d .4,11~ma~v~s 4.doc --
V~ Vanasse Hangcn Brustlin, ~n¢. Revised Draft May 16, 2001
of suspended sediments in the North Fork Rivanna River at higher
pumping rates.
In addition, in order to describe an alternative that would take
advantage of the existing 2 mgd treatment capacity of the North Fork
Treatment Plant, to the extent that it is practicable to do so, while
avoiding major infrastructure costs associated with other variations of
this alternative, a drawdown of 0.5' u~li~ing a direct stream release was
analyzed. This represents the maximum use of the existing North Fork
facilities that is feasible given existing constraints on pump usage and
maintenance. However, there is insufficient water demand presently for
use of this Water in the northern segment of the Urban Service Area, and
infrastructure does not currently exist for distributing this water to the
main portion of the service area to the south.
Effectiveness
The various drawdowns provide additional safe yield as follows:
· 0.5' - 0.7 mgd
· 5'-2.9mgd
· 10'- 4 mgd
· 15' - 4.8 mgd
· 20' - 5.5 mgd
Practical difficulties assodated with capturing the released water and
limited demand in the northern portion of the Urban Service Area at
present minimize the overall effectiveness of the 0.5' option. Specifically,
drawing higher volumes of water through the North Fork intake results
in damage to the pumps, because rocks and other debris are drawn in
along with the water. The estimated 0.7 mgd increase in safe yield
results from an estimate of the upper end of the range of water that can
effectively be withdrawn. However, there is no need for this water at
present in the northern portion of the Urban Service Area and it would
have to be transmitted south, involving additional infrastructure
expense, to be beneficial to the system.
Practicability/Cost .
The total costs for 0.5' option is-low, while the other variations are
moderate to relatively high in comparison to other alternatives:
· 0.5' - $500,000
· .5' - $12.8 million
· - 10' - $15.5 million
· 15' - $17.8 roi11ion
· 20' - $20.1 million
As stated above, the 0.5' option would utilize existing treatment
capacity, and would require limited infrastructure improvements to
serve the North Fork service area. The $500,000 estimate covers the cost
Recommended Alternatives
18
\\Vawill~rojec~k30~O2~WP~,EPOR~mm~a~a Ai~rn~iv~ 4.doc
~ Vana.~e Hangen Brustlin. Inc. Revised Draft May 16, 2001
for control and gauging improvements at the dam, as well as valving
improvements in the North Fork distribution system.
Costs for the other options include the additional infrastructure
necessary to transport the water from Chris Greene Lake south to the
primary portion of the Urban Service Area, where the vast majority of
the water demand is located. These improvements would consist of
roughly 6 miles of 24" water main from the North Fork water treatment
plant to the vicinity of the South Fork water treatment plant, at an
estimated cost of $5.4 million. For the 5' drawdown, this increases the
total project cost by 73%, and for the 20' option by 37%. This additional
cost was not included in the original estimate, and is not reflected in the
Alternatives Matrix. It is_ possible' that a portion of these costs could be
borne by the Virginia Depa~Lment of Transportation, as part of the Route
29 improvement project.
It is possible that long-term growth could increase demand in the North
Fork service area. If this proves to be the case, use of Chris Greene Lake
for water supply purposes could become more cost-effective as it would '
not be necessary to transfer this water further south.
As drawdown levels increase above the 0.5' option, the unit cost and
total project cost increases substantially, because of the improvements
necessary to treat the additional volume of water at the North Fork plant,
which currently has only 2 mgd of treatment capacity. For the 20'
option, these improvements would cost $13.25 million (66% of the 20.1
million total). In contrast, the 4' crest control alternative would utilize
existing capacity at the South Fork treatment plant. Although using
Chris Greene Lake for water supply may not be cost-effective at this
time, some version of this alternative may become attractive in the
future, depending upon whether and to what extent demand in the
northern portion of the Urban Service Area increases in the future.
The total cost of this alternative could increase further if Albemarle
County were required to replace any impacted recreational facilities,
which were constructed at Chris Greene Lake using Land and Water
Conservation FundS. If recreation of any kind were eliminated or
suspended, Albemarle County would have to develop a replacement
facility of equal recreational usefulness as determined by the State
Comprehensive Outdoor Recreation Plan. Although the value of the
recreational facilities at the lake is uncertain, recent recreational
improvements made by the County at Walnut Creek and Darden Towe
Memorial Park suggest that replacement could cost approximately $4
nl~ion.
Environmental
One of the primary issues with the drawdown alternatives is the impact
to recreation (fishing, swimming, and boating) and fish stocks at Chris
Greene Lake. AccOrding to the Virginia Departatent of Game and Inland
Fisheries, paid attendance at the lake is approximately 20,000 people per
year. This figure does not account for full attendance, because the fees
are only in effect for a certain part of the year, and then only during
Recommended Alternatives
19
\~Vawill~p~oje~s~0S02~Wl~Rl~PORTS'~R~-ommended AJlm-a~v~ &doc
~ Varmasc Hangcn Bru~flin, Inc. Revised Draft May 16,"2001
certain hours of the day. DGIF has further indicated that drawdowns in
excess of' 5'-7' could result in severe predation of that year's fish fry,
resulting in significant decline of the year's stock.
The frequency of these events would be roughly once per decade. The
durations of the drawdowns are shown in Figures 5-8.
The Virginia DepaxLment of Health has raised concerns about allowing
of primary contact recreation (swimming) should the lake be utilized for
water supply purposes via the direct pipeline method described in the
Alternatives Evaluation. Given the practical difficulty of capturing the
water in the stream release option and existing pump damage and
maintenance issues at higher pumping rates, the direct pipeline
represents the only way to assure access to the safe yield provided by the
drawdown. In a written response, the VDH has raised the possibility
that use of the lake for water supply could result in prohibition of all
· primary contact recreation. This would represent the loss of a significant
community amenity, and. could also have cost implications, as discussed
above.
Finally, lowered pool levels would temporarily impact wetlands and
submerged vegetation, but are not anticipated to have long-term
impacts. Pipeline construction could result in impacts to less than 1 acre
of wetlands.
Recommendation .-
Drawdowns at Chris Greene Lake offer a potentially viable future
alternative, especially if and when demand should increase in the
northern end of the service area. Currently, little demand exists in the
-northern area (less than 0.3 mgd), and the cost for treating and
transporting water from Chris Greene Lake to the south makes this
alternative less attractive in the short term.
Utilization of the 0.5' drawdown should be seen as a potential
emergency measure during severe drought periods. The difficulties
associated with withdrawal using the direct stream release and the lack
of demand for the resulting yield in the northern portion of the service
area make full time use of this option impracticable at present.
Significant impacts to recreation and fish stocks would also accompany
the versions of this alternative with higher drawdowns and yields.
Given the higher costs, smaller yield, and negative impacts to fish stocks
and recreational amenities associated with higher drawdowns and
yields, implementation of 4' crest controls is a better candidate for
immediate implementation than using Chris Greene Lake. Immediate
implementation of the 5' drawdown version of this alternative would
involve much greater costs and provide only about 15 years of additional
supply. That is insufficient t/me to fully assess reservoir sedimentation
rates and controls, and the alternative would do nothing to extend the
Recommended Alternatives
~Vaw ~.lect sL.,*.*.*.*.*.*.*.*.~0~c2X.~TSLReco mmended Alzgt'natives 4.do~
20
Chris Greene Lake Water Levels Based on Drawdown Up To 5 Feet
Water Stage(ft) (Record Period: 10/01/1929-12/31/1989)
423.5
422.5
422.0 ~ ~- 35 Days below 423 Feet -
421.5- , __ Minimum 1 Day Level of 421.80 Feet
420.5 --
420.0 65 Days below 423 ~:eet
'164 Days below 423 Feet -- 18 Days below 420 Feet
419.5 -
56 Days below 420 Feet Minimum I Day Level of 418.20 Feet
419.0 Minimum I Day Level of 418.80 Feet
418.5
418.0
423.5
423,0
422.5
422,0
421,5
421.0 -
420.5
420.0 ·
419.5-
419.0-
418.5-
418.0
-~J59 Days below 423 Feet
Minimum I Day Level of, 422,20 Feet
1/1/60 1/1/65 1/1/70 1/1/75
1/1/80 1/1/85
Figure 5
Water Stage(fi)
423.5 ~ , ,
422.5 ~ ~--'~t - - ----
4215 L--L __~J__~J95 Days below 423 Ft
'I I ]J--~]39 Days below 420 Ft
420,5 1---~, --~-~1Minimum 1 Day Level of 417,6 Et
"' b-tl
416.5 --~. 1 la Days below 423 Ft
4155 ~ Minimum 1 Day Level of 420.2 Ft [_
414.5 --'~1 1242 Days below 423 Ft
Ii
413.5 ------~1190 Days below 420 Et
412 5 lMinimum 1 Day Level of 41&0 Ft ~.~ ,
Chris Greene Lake Water Levels Based on Drawdown Up To 10 Feet
(Period of Record: Oct. 1, 1929-Dec.31 ~ 1989)
10/1/29 10/1/34
J75 Days below 423 Ft
-136 Days below 420 Ft
lMinimum 1 Day Level of 413.0 Ft
.t38 Days below 423 Ft J----
~Minimum 1 Day Level
Jof 422.0 Ft
10/1/39 10/1/44 10/1/49 10/1/54 10/1/59
423.5
422.5
421.5-
420.5
419.5
418.5 -
417.5-
416.5
1/1/60
--147 Days below 423 Ft i
Minimum 1 Day Level of 422.20 Ft
I
63 Days below 423 Ft |
24 Days below 420 Ft
Minimum 1 Day Level of 417.3 Ft
1/1/65 1/1/70 1/1/75
1/1/80 1/1/85
Figure 6
Chris Greene Lake Water Levels Based on Drawdown Up To 15 Feet
water Stage(ft) (Period of Record: Oct. 1, 1929-Dec.31, 1989)
422.5 1 ! :
hl-t- /
416.5 -
412.5 , I J Minimum 1 Day Level of 415.2 Ft
408.5 t--~-j~20 Days below 423 Ft
4~5 ~1187 Days below 420 Ft /
' Da~s below 410 Ft /
I53 Days below 420 Feet
! 8 Days below 410 Feet
JMinimum I Day Level of 408.3 Feet
10/1/29 10/1/34 10/1/39 10/1/44 10/1/49 10/1/54 10/1/59
424.5
422.5
420.5
418.5
416.5
414.5,
412.5 -
410.5 -
408.5
1/1/60
· '11
--~76 Days below 423 Ft
433 Days below 420 Ft
JMinimum I Day Level of 413.8 Ft
1/1/65 1/1/70 1/1/75
1/1/80 1/1/85
Figure 7
Water Stage(fi)
422.5
Chris Greene Lake Water Levels Based on Drawdown Up To 20 Feet
(Period of Record: Oct. 1, 1929-Dec.31, 1989)
~~L .t79 Days below 423 Ft
i ,ow j
.-- -~-IMinimum I Da}, Level of 411.6 Ft
----~-~229 Days below 423 Ft
____[JJ212 Days below 420 Ft
1105 Days below 410 Et
----~Minimum 1 Day Level of 403.3 Ft
420.5
418.5
416.5
414.5
412.5
410.5 ·
408.5 -
406.5 -
404.5 -
402.5
10/1/29 10/1/34 10/1/39
180 Days below 423 Feet
61 Days below 420 Feet
20 Days below 410 Feet
Minimum 1 Day Level of 1403.9 Feet
44 Days Below 423 Ft
11 Days Below 420 Ft
Minimum 1 Day Level
of 203.90 Ft
10/1/44 10/1/49 10/1/54 10/1/59
424.5
_~90 Days below 423 Ff J
Minimum 1 Day Level of 420.0 Ft__ 5090 DaysDays belowbel°w 420423 FtFt
, Minimum 1 Day Level of 410.6 Ft
422.5
420.5
418.5
416.5
414.5
412.5
410,5
408.5
111160 I/1/65 1/1/70 1/1/75 111180 1/1/85
Figure 8
Vanasse Hangen Brusflin, Inc. Revised Draft May 16, 2001
use~d lde of the SFRR. Accordingly, we recommend reserving this
alternative for possible future implementation after 4' crest controls.
5. Use Chris Greene Lake as a
Pumped Storage Reservoir
Description of Alternative
This alternative consists of withdrawing water from the North Fork
Rivanna River and pumping it to Chris Greene Lake.
Effectiveness
This alternative would provide no increase in safe yield due to lack of
storage capacity in the lake during non-drought conditions and lack of
sufficient flow in the North Fork Rivanna River during those times when
storage is available.
Practicability/Cost
No costs were developed, due to unfeasibility.
Environmental
This alternative would have minimal environmental impacts.
Recommendation
Because it would provide no safe yield, we recommend that this
alternative not be included as part of a practicable solution.
6. Use Beaver Creek Reservoir to
Supplement Flows in Mechums River
Description of Alternative
This alternative involves conveying water from Beaver Creek Reservoir
to the Mechurns River to supplement flows to the SFRR during severe
drought conditions.
Recommended Alternatives
\~Vawill~rojeczsk3OSO2~Wl~REPORTS'd~co~ A]tenudves 4,doc
21
* ~ Vana~se Han~,¢n ltnr~rlin, Inc. Revised Draft May 16, 2001
Effectiveness
This alternative is not effective, because water demand in the Crozet area
is expected to utilize the entire safe yield of Beaver Creek by 2050.
Furthermore, the ability to capture a significant portion of any in-stream
release is uncertain, and would depend on stream characteristics.
Specifically, during drought conditions, when this alternative would be
needed, the receiving streams could be-sufficiently dry that a significant
portion of the release would be lost to infiltration. The only method of
documenting this possibility is field-testing during such drought
conditions.
Practicability/Cost
A cost of $500,000 is included for necessary flow measuring equipment
downstream of the reservoir.
Environmental
Minimal environmental impacts would result from implementation of
this alternative.
Recommendation
Because it would provide no safe yield, we recommend that this
alternative is not part of a practicable long-term solution. However, in
the short-term, before demand in Crozet reaches the 2 mgd level, Beaver
Creek could offer some additional yield. We therefore recommend that
necessary evaluations take place during the next severe dr6ught.
7. Dredge Sugar Hollow Reservoir
Description of Alternative
Dredging of Sugar Hollow would consist of a one-time dredge event to
remove landslide debris and bottom sediment, returning the reservoir to
its original capacity. Given the slow rate of sedimentation in Sugar
Hollow, annual maintenance dredging is unnecessary.
Effectiveness
This alternative would provide only 0.1 mgd in additional safe yield as
of 2050.
Recommended Alternatives
\\Vawill~.~0502~Wl~REPOR~ommende. d Altm'nalives 4.doc
22
Yaaa~e I~g~ Br~. Inc. Revised Dm~ May 16, 2001
Practicabili~lCost
~g ~e rese~o~ wo~d be accomp~hed at a cost of ~.9 millio~
Environmental
The one-time dredging event described herein would impact
approximately 2 acres of wetlands, as well as limited areas of shallow
water habitat. Furthermore, temporary water quality impacts could be
expected, as described in the SFRR dredging section.
Recommendation
Despite limited environmental impacts, the high unit cost and minimal
yield of this alternative lead us to recommend that it is not part of a
practicable solution at this time.
8. Conversion of Ragged Mountain to
Pumped Storage Reservoir
Description of Alternative
This alternative involves withdrawing water from the Mechums Rive~
and pumping it to Ragged Mountain Reservoirs by rehabilitating and
expanding an existing abandoned intake and pump station. The dam at
Lower Ragged Mountain Reservoir would be raised by 50' and the dam
between the two reservoirs would be inundated. Furthermore, the
alternative includes new infrastructure and expansion of the
Observatory water treatment plant.
Effectiveness
This alternative would provide 10 mgd in additional safe yield.
Practicability/Cost
Ragged Mountain conversion has a relatively high cost of $47 million.
Environmental
The new pool level would inundate approximately 5 acres of wetlands.
As is the case with SFRR, these wetlands would be replaced by new
wetlands colonizing the new pool fringe. Furthermore, the Virginia
Depath~Lent of Game and Inland Fisheries has expressed concern that
Recommended Alternatives
23
\Wawfll~pmjects~0502~WP~EPORTS~Recommende~, Alten~ives 4.doc
Vana~e Haagcn Bru~fli~ Inc. Revised Draft May 16, 2001
withdrawals could impact the fishery in the Mechums River. The
presence of the James spinymussel in the Mechums also raises the
prospect of negative impacts to a rare and endangered species.
Recommendation
Although this alternative would provide significant safe yield, it appears
that other, more cost-effective alternatives are available. It is possible
that there are impacts to the fishery in the Mechums River, and to rare
and endangered species; such potential impacts should be investigated if
this alternative is further pursued. We therefore recommend that
conversion of Ragged Mountain is not part of a practicable solution at
this time.
9. Indirect Reuse
Description of Alternative
Indirect reuse involves treating sewage at the Moore's Creek advanced
wastewater treatment plant to a higher purity, and pumping the treated
effluent to either the Mechums or the Moorman's River. The effluent
would then flow downstream into the SFRR, thereby augmenting
available water supply. The alternative includes enhanced wastewater
treatment, pumping/pipeline infrastructure, and expanded drinking
water treatment capacity.
EffectiveneSs
Indirect reuse represents a highly reliable source of water supply that
can meet demand even'during the most severe drought. This would
occur because as demand increases, water treated at Moore's Creek
would increase, proportionately increasing the amount available to
pump back to the system. For purposes of evaluation, the alternative has
been analyzed at 15 mgd, an amount adequate to meet water supply
needs throughout the planning period.
Practicability/Cost
Refining the cost estimate for this alternative is complicated by the fact
that the state has no guidance in place for the level of water treatment
and quality that Would be required; reuse permits are analyzed on a
case-by-case basis. Based on the best available information, the
Alternatives Analysis assigns to the Mechums River option a cost of $56
million and an annual operating cost of $150,000, which includes energy.
costs (it should be noted that potential energy costs were considered for
all alternatives). Applicable figures for the Moorman's option are $69
million and $280,000 annual operating.
Recommended Alternatives
24
\\vawill~projecc~..~0502~WP~REPORTS~R~o mmende~ Allm'na~v,~ 4.doc
' ~ Vanasse l-lang-~n Bmstlin~ Inc. Revi~ed Draft May 16, 2001
At the request of the Virginia Depa~h~tent of Health 'Cv'DH), the study
team Performed a review of the treatment approach used by the Upper
Occoquan Sewage Authority (UOSA), as a point of reference for
"indirect reuse" in Virginia. The memorandum included in Appendix D
documents our findings.
While the findings are interesting, evolution of water and wastewater
treatment technology would probably lead to a different approach for
RWSA. For example, ultraviolet disinfection is now recognized as an
effective technique for disinfection of cryptosporidium, giardia and
many other organisms, and would likely be preferred over high lime
(pH) treatment for disinfection. Pinpointing the cost for enhanced
treatment by RWSA's water and wastewater treatment plants is not
possible because VDH does not yet have dear water quality objectives
that apply to indirect reuse. Therefore, the indirect reuse alternative
should anticipate a wide range of costs for additional wastewater or
water treatment processes, ranging up to roughly $3/gpd (at 15 mgd this
equates to $45,000,000). Most likely, the cost would range from $7 - $30
million. It Should also be recognized that some or all of these same
upgrades may become future requirements of the Safe Drinking Water
Act or Clean Water Act, whether or not indirect reuse is implemented.
Finally, it is not dear that the virgim Depa~h~tent of Health would
allow indirect reuse in this case. The Depa,'La'tent's regulations require
selection of the most pure source. Because other, more pure sources are
available, the Department may simply not allow this alternative as is
reflected in its comments to-date. The VDH has stated that this
alternative does "not reflect prudent public health and source water
quality considerations" (letter to Mr. Arthur Petrird of January 10, 2001).
Environmental
Neither of the indirect reuse options would adversely affect streamflows,
either in the Rivanna River or the receiving river. During drought
conditions, indirect reuse would reduce augmentation of flow in the
Rivanna resulting from the discharge at Moore's Creek, and would
augment flows in the receiving river. During severe droughts, flow in
each river approaches 0 mgd. Under this alternative, gradual activation
of the pumpback, commensurate with the severity of the drought, would
result in maintenance of normal flow levels. This would be a substantial
benefit to many species that cannot migrate to other habitats during such
stressful events.
The pipeline for the Mechums option would impact approximately 2
acres of wetlands, while the Moorman's pipeline would impact
approximately 5 acres.
The James Spinymussel has been identified in the Mechums River in the-
vicinity of the proposed project. Because this alternative would be
utilized only during, severe droughts, and would maintain normal
Recommended Alternatives
V~V aw/ll~pro~m'tak3OS02~Wt~R.~ORTS~:o mm~ded ARemative~ &doc
25
° ~ Vanasse Hangen Brustlin, Inc. Revised Draft May 16, 2001
stxeamflows, it is unclear whether effects on the James spinymussel
would be positive, negative, or neutral
Recommendation
Indirect reuse would provide substantial and reliable safe yield adequate
to meet long term demand. Its costs, however, are high and also
uncertain, and the alternative involves potential impacts to endangered
species. Furthermore, the option may not be allowed at all by the
Virginia DepaxbaLent of Health. We recommend that indirect reuse not
be considered part of a practicable solution at this time.
10. Growth Management
Description of Alternative
The growth management alternative involves modification of Albemarle
County's current growth management policies, which have been shown
effective in meeting their goal of directing the majority of new resiElential
development into the Urban Service Area. Changes to these policies
would likely displace growth into the surrounding rural areas, given the
limited growth management authority granted to local governments, in
addition to property rights issues and political/economic realities.
Effectiveness
Assuming. a reduction in the proportion of growth in the Albemarle
County portion of the Urban Service Area to 50% (the Demand Analysis
assumed this proportion to be 66%), the Urban Service Area would have
a 2050 population of approximately 93,000 persons rather than the
ll0,000 persons as projected in the Demand Analysis. This would
represent a decrease in the projected 2050 water, demand of
approximately 1.7 mgd. It is possible that a range of growth
management strategies could be employed to reduce demand; this
alternative represents the highest likely reduction that can reasonably be
expected from growth management.
Practicability/Cost
Reversal of current growth management policies could have significant
logistical impacts on future development and ultimate costs, but these
are not quantifiable. Politically, reversal of growth management policies
may not be feasible or practicable. Albemarle County currently
implements an effective growth management plan designed to
concentrate growth in the Urban Service Area. It may prove impossible
simultaneously to prevent this growth from occurring within the Urban
Service Area while preventing it from moving elsewhere in the County.
Recommended Alternatives
26
\~VawilEpm~'~0502~ORTSkReco mmenO~ Alummuv~ 4.doc
Vanasse Hangen Bmsflin, Inc. Revised Draft May 16, 2001
In any event, there are no data or proposed policies now in existence that
wold demonstrate the practicability and costs of this alternative.
Environmental
If development were dispersed into the rural areas of the-County by
policies restricting growth within the Urban Service Area, that displaced
development would utilize private wells and septic systems.
Futherrnore, secondary-impacts would include construction and
maintenance of infrastructure improvements to roads and utilities.
Transportation and safety impacts would include longer trips for school
buses and commuters, as well as increased time for dehvery of
emergency services and public transportation.
Recommendation
The potential reduction in the future water deficit attributable to this
alternative would not be realized for many years and is' not sufficiently
great to obviate the need for an interim solution such as 4' crest controls
at SFRI~ Furthermore, the growth management alternative 'would
reverse an effective existing policy that enjoys public and political
support at present. The resulting consequences and costs of this
alternative are difficult to predict but may be significant. We
recommend that this alternative should continue to be considered and, if
growth restricting policies are adOpted in the future, their effectiveness
can be assessed and factored into any decision to pursue additional
alternatives in the middle and later portions of the study period.
However, this alternative should not be considered part of a' practicable
solution at this time.
11. Leak Detection and Control
Description of
Alternative
This alternative consists of accounting for and correcting sources of
system water loss. ACSA and the City currently implement leak
detection and meter calibration programs to respond to and correct
water loss.
Effectiveness
Overall documented system losses indicate that the entire system is
operating within accepted limits. It does not appear that additional
measures would be effective in reducing water demand beyond the
impact of ongoing efforts.
Recommended Alternatives
27
\~V awillkpro.~ts~O~O~RT~omln~ld~[ .Alternatives 4.doc
~r~ Vanasae Hangcn Brustlin, Inc. Revised Draft May 16, 2001
Practicability/Cost
Since additional measures would not be effective, no additional costs
have been calculated.
Environmental
Current efforts appear to have no negative environmental impacts.
Recommendation
Because ACSA and the City currently have effective leak detection
programs, additional measures would not be effective. We therefore
recommend that this alternative is not part of a practicable solution.
B. Physical Additions to the Existing Water
Supply System
1. Groundwater
Description of
Alternative
The Alternatives Analysis investigated two options for utilizing
groundwater resources. The first, aquifer storage and recovery, involves
seasonal underground storage of treated drinking water and subsequent
withdrawal to meet demand during shortages. The second, conventional
withdrawal of groundwater, includes installation of shallow wells and
piping to the South Fork and North Fork water treatment plants.
Effectiveness
Because of geological conditions, aquifer storage and recovery appears to
be technically unfeasible in the Charlottesville-Albemarle area.
Conventional withdrawal of groundwater from 15 wells would provide
0.1 mgd in additional safe yield.
Recommended Alternatives
'~\VawOl~.lects'c3OSO2~WPd~aPORTS~.ecotnm~ _.3~_~_ Altemat2wes 4.doc
28
~r~ Waas~e Hangen Bru~din~ Inc. Revved Draft May 16, 2001
Practicability/Cost
Given the unfeasibility of aquifer storage and recovery, no costs were
calculated. Installation of 15 wells conveys a cost of $1.2 million, at a
very high unit cost of $12/gallon.
Environmental
Due to unfeasibility, environmental review of aquifer storage and
recovery was not necessary. The impacts of conventional withdrawal
would be minimal.
Recommendation
Groundwater options do not represent part of a practicable solution.
2. Reservoirs
Description of Alternative
The Analysis of Alternatives investigated 7 options for new water supply
impoundments, including a reservoir on Buck Mountain Creek ufili~ng
land currently owned by RWSA.
Effectiveness
All of the reservoir alternatives provide additional safe yield, ranging
from 5.6 to 16.4. Certain of the reservoirs would cover the full 15 mgd
safe yield deficit for 2050.
Practicability/Cost
The reservoirs range in cost from $26 million to $118 million. They have
relatively high unit costs ranging from $3.96/gallon to $14.22/gallon.
Environmental
All of the reservoir options involve residential displacements, impacts to
cultural resources, and wetland impacts ranging from 52 acres to 144
acres.
In addition, several reservoir options involve impacts to the James
spinymussel.
Recommended Alternatives
~\VawilI~pr oJec~0/$O2~WP~REPORTS~Rc~omm~n~mi Ad~m~ives &doc
29
Vanassc Hangcn Brustlin, Inc.
Revised Draft May 16, 2001
Recommendation
Although the reservoir alternatives would provide significant safe yield,
they all involve residential displacements, impacts to cultural resources,
and wetland impacts. Also, they have relatively high to very high unit
costs. Accordingly, we recommend that these alternatives not be
considered part of a practicable solution at this time.
3. James River Withdrawal at Sco~ville
Description of Alternative
The James River withdrawal includes construction of an intake, pump
station, and 29 mile pipeline to withdraw water from the James and
pump it.to the South Fork water treatment plant (which would require
expansion).
Effectiveness
This alternative would provide 15 mgd in additional safe yield as of
2050.
Practicability/Cost
The James River withdrawal would cost approximately $72 million. The
unit cost for this alternative is $4.80/gallon, relatively high compared to
the other alternatives.
Environmental
Implementation of the withdrawal would impact approximately 5 acres
of wetlands - mitigation would be provided. The alternative also
involves potential impacts to cultural and historic resources that would
require additional investigation.
A withdrawal of this scale 'would have minimal impacts to flows in the
James River, even if other withdrawals occurred in the vicinity. Figure 9
shows flow exceedance curves with and without the project, while
Figure 10 compares flow exceedance curves with no withdrawal versus
with RWSA withdrawal plus a proposed power plant withdrawal in the
same vicinity.
Recommendation
This alternative offers a practical source of water sufficient to meet' long
term demand in the Urban Service Area. Furthermore, the associated
Recommended Alternatives 30
\~Vawill~proleClSk30~02!.~TSXRecomm~ded Al~mafive~ 4.doc
Flow (mgd)
1400
1200
Flow Exceedance Curve for James River at Scottsville
(RWSA Withdrawal 15 mgd)
Period of Record: Oct. 1, 1924-Sept.30, 1999
1000
800
600
400
200
d --e-- RWSA Withdrawal
l'~ No RWSA Withdrawal_J
Exceedance Percentage
Figure 9
Flow (mgd)
1400
Flow Exceedance Curve for James River at Scottsville
(RWSA Withdrawal 15 MGD and Power Plant Withdrawal 8 MGD)
Period of Record: Oct. 1, 1924-Sept.30, 1999
1200
1000
8OO
6OO
400
200
Exceedance Percentage
--e-- RWSA and Power Plant Withdrawal
~-~--No Withdrawal
Figure 10
Vanasse I-Iangeu BrusOin, Inc.
Revised Draft May 16, 2001
environmental impacts are relatively minor. The unit cost, howeveL~ is
relatively high, and we recommend that the 'alternative not be
considered part of a practicable solution at this time.
4. Rivanna River Withdrawal
Description of Alternative
To withdraw surface water from the Rivarma River, this alternative
includes construction of an intake[ pump station, treatment plant, and
pipeline. It also utilizes the existing water main along Route 250 serving
the Village of Rivanna.
Effectiveness
This alternative would provide additional safe yield of 4.7 mgd in 2050.
Practicability/Cost
This alternative would cost approximately $18 million. The unit cost is
$3.83/gallon.
Environmental
Pipeline construction would impact approximately 2 acres of wetlands,
for which mitigation would be included.
Figures 11 and 12 demonstrate the minimal impact of the withdrawal,
which amounts to an indirect reuse of water through the system-
The Virginia Departaient of Health has expressed water quality concerns
about this alternative, which is similar to indirect reuse.
Recommendation
The Rivanna River withdrawal has a relatively high unit cost, and raises
public health' concerns (as expressed by the VDH). We recommend that
it not be considered part of a practicable solution at this time.
Recommended Alternatives
~,~V awiH~j~tsk30502~R'FS'~R~ omme~de~ Altermitives 4.¢1oc
31
Year 2050 Flow Schematic for
Rivanna River Alternative
(without Gienmore withdrawal)
File No, 5036.002
Date: November 29, 2000
Figure 11
ENGINEERS,
~[~ Rivanna River Flow (+7 MGD)
Year 2050 Flow Schematic for
Rivanna River Alternative
(with Glenmore withdrawal)
File No, 5036.002
Date: November 29, 2000
Figure 12
~ -- ENE~INEEF~S, INC
~t'lv[~ Vanasse Hangen Brustam Inc. Re~,ised Draft May 16, 2001
5. Mechums River Withdrawal
Description of Alternative
Withdrawal from the Mechums involves rehabilitation of the abandoned
intake and pump station near Lake Albemarle. Water would be pumped
to the Ragged Mountain Reservoirs.
Effectiveness
This alternative would provide limited safe yield of 0.2 mgd, and only
when droughts occur in successive years.
Practicability/Cost
The total cost for this alternative is approximately $850,000.
withdrawal has a relatively high unit cost of $4.25/gallon.
The
Environmental
Information from the Virginia Department of Conservation and
R_~eation and the Virgirda Depmhatent of Game and Inland Fisheries
indicated that the James spinymussel has previously been identified
upstream and downstream of the prOposed withdrawal location,
Additional investigations would be necessary to determine potential
impacts.
Recommendation
This alternative provides extremely limited yield, has a high unit cost,
and involves potential impacts to the James spinymussel. Accordingly,
We recommend that it not be considered part of a practicable solution at
this time.
6. Regional Cooperation
Description of Alternative
Regional cooperation involves a joint proiect to meet the needs of the
Urban Service Area and the needs of nearby water suppliers. Based on
investigations described in the Analysis of Alternatives, the best prospect
appears to the Rapidan Service Authority. To cooperate with that
agency, a water main would be constructed along U.S. Route 29 to
Greene County.
Recommended Alternatives
32
~\Vawil~0mle~s~OSO2~R~mme-n~d Alte~ratives 4.doc
]/']~ Vanasse Hangen Brustlin, Inc. Revised Draft May 16, 2001
Effectiveness
This alternative actually results in a demand increase of 3 mgd through
2050, thereby exacerbating the projected water deficit.
Practicability/Cost
The cost of the water main is estimated at $3.1 million.
Environmental
Construction of the pipeline would impact less than I acre of wetlands.
In addition, there could be environmental impacts associated with
development of the additional 3 mgd of water supply.
Recommendation
Because this alternative increases demand and exacerbates the projected
water supply deficit, we recommend that it not be considered part of a
practicable solution at this time.
o
7. No-Action
Description of Alternative
No-Actic~n means that nothing would be done to address the projected
water supply deficit for the Urban Service Area.
Effectiveness
The No-Action alternative would result in failure of the public water
system to meet either existing or future water demand. Safe yield would
fall to 4.6 mgd in 2050, while demand increased to approximately 20
mgd.
Practicability/Cost
The No-Action alternative is considered impracticable owing to the
socioeconomic impacts, public health and safety implications, and legal
and political responsibilities of local governments.
Recommended Alternatives
\\VawilI~proIecmk30502~WI~REPOR'I'SXRa~°~ Alternatives 4.doc
33
~ ~ Vanasse l-langen Bmstlin, lac. Revised Draft May 16, 2001
Recommendation
We recommend that this alternative not be considered part of a
practicable solution at this time.
ConcluSions
The evidence and recommendations presented above point to a strategy
that will provide needed water supply, both immediately and into the
future, while allowing RWSA to maintain maximum flexibility in
implementing long-term improvements.' The focus on demand
management, sedimentation control, enhancement of existing water
resource development, and reliance on existing treatment capacity offer
an envirorLmentally sensitive; cost-effective approach.
Several of the alternatives analyzed would meet the entire projected
water deficit in 2050. Nevertheless, many of these involve high cost
and/or significant environmental impacts. Furthermore, because the
long-term effects of sediment reduction and water conservation are
uncertain, a phased implementation strategy allows opportunity to
monitor these alternatives. The 4' crest controls are one of the few
improvements that would provide sufficient time (until approximately
2035) to do so. The only negative environmental effects associated with
raising the pool elevation (wetlands inundation) can be effectively
mitigated.
Use of Chris Greene Lake for water supply would not provide sufficient
safe yield to allow the time necessary for monitoring of sedimentation
and conservation. It would require plarmmg for implementation of other
alternatives within about 10 years. Second, its costs are order-of-
magnitude greater than the costs of crest controls, in part because of the
logistical difficulties and additional infras~c~e improvements
required to treat and transport the water. Third, use of Chris Greene
Lake for any substantial yield would have significant negative effects on
a regional recreational resource that may be difficult to offset.
In order to determine the appropriate release from the SFRR that could
be implemented in conjunction with the 4' crest controls, additional
analysis of flow levels and safe yield impacts has been performed since
publication of the Analysis of Alternatives. The results are shown in
Figures 13 and 14.
Figure 13 shows the flow exceedance curves for the South Fork Rivanna
River downstream of the dam with releases including the proposed 8
mgd minimum and also ranging from 8 mgd or inflow to 32 mgd or
inflow. These data represent variations of the revised release scenario,
uHl~zing a release trigger level, at which point the release volume would
equal inflow to the reservoir. As can be seen, except at very high
percentage frequencies, the various scenarios are not significantly
different in terms of downstream flow. The various releases would
result in similar downstream flows roughly 83% of the time. The
Recommended Alternatives
34
\\Vawil.~rojec~k30502XWP'~-~PORTS~R~ro~d~d ~v*s 4.doc
~ Vanaas,' Hangcn Bmstlin. Inc. Revised Draft May 16, 2001
horizontal sections of the alternate release lines show the brief periods of
time during which .constant "trigger" releases would be maintained,
before releases equaled inflow. The proposed scenario is the only case in
which flows do not drop below 8 mgd.
Figure 14 compares the effect of the various release scenarios on safe
yield provided by the crest controls. As the graph demonstrates, yield
drops precipitously as release thresholds increase.
In order to balance the usefulness of the crest controls in providing safe
yield, while providing environmental benefit in the form of increased
downstream flow, we suggest that a constant 8 mgd minimum release
regime might be implemented. This is the scenario outlined in the
Analysis of Alternatives as well as earlier in this document. This would
provide additional safe yield of 7 mgd in 2050, and would actually
augment flows in the river during severe droughts. This strategy would
follow the temporary use of the revised release of 8 mgd or in/iow
recommended herein for the short-term.
Temporary use of the revised release, implementation and monitoring of
sediment control, drought management, voluntary conservation, and
pursuance of 4' crest controls with an 8 mgd constant release represent a
package of viable alternatives that appear best to satisfy applicable
considerations. This combination would meet the needs of the Urban
Service Area through approximately 2035, allowing adequate time to
monitor and select future, longer-term measures as necessary. The
combination is cost-effective, incurs minimal environmental impacts,
benefits flow in the Rivanna River below the dam, and prolongs the
useful life of SFRR-
Recommended Alternatives
\~V awill~projec~L~0502~WPkREPOR'l'SXRtco~e~l AltemaUVeZ &doc
35
F~ow E×ceedance Curve for South Fork Rivanna Reservoir Downstream of Dam
Downstream Flow (mgd) Period of Record: Oct~ 1,1929-Sept.30, 1999
t00 '~
9O
8O
7o!
5O
4O
3O
--~--Crest Control w~ 8 mgd Constant Release ® Crest Control w/8 mgd Alternate Release
+-.,-Crest Control w/12 mgd AItemate Release
Control w/16 mgd Alternate Release
-a~--Crest Control w/32 mgd Alternate Release
E×ceedance Percentage
Figure 13
Safe Yield of South Fork Rivanna Reservoirw/4' Crest Control and Alternate Releases
Safe Yield (mgd)
6
5
4
2
5 10 15 20 25 30
Alternate Release (mgd)
35
Figure 14
~ '~]r] Vanasse l-lan~ Brasttin. Inc. Revised Draft May 16, 2001
Appendices
Appendix A: Supply Analysis Executive
Summary
Vanasse Hangen Brustlin, Inc. (VHB) has been authorized by the
Rivanna Water & Sewer Authority (RWSA) to prepare a raw water
supply study to evaluate the future water needs of the RWSA's Urban
Service Area which includes the City of Charlottesville and surrounding
areas. O'13rien & Gere Engineers, Inc. serves as a subcontractor to VHB
on various aspects of the raw water supply study.
Among the initial efforts as part of this study are tasks to: (l) estimate the
current and future safe yield of the existing raw water supply system
and, (2) project future water demand through the year 2050. A
comparison of safe yield and demand projections will enable the RWSA
to better understand whether'and when it may face a water deficit, and
the magnitude of any such deficit. Subsequent studies will include an
analysis of alternatives to address any water deficit. Alternatives to be
evaluated will include, but will not necessarily be limited to, new
sources of supply, water conservation programs, demand control
measures, and options to restore or increase the safe yield of existing
souTces.
This report summarizes the results of a raw water safe yield review of
the existing RWSA Urban Service Area system as it has historically
operated. This system includes the (1) Rivanna Reservoir, (2) Sugar
Hollow/Ragged Mountain Reservoir system, and (3) North Fork
Rivanna River Intake. For purposes of this analysis, ".safe yield" is
defined as the maximum raw water yield that can be supplied
consistently over the long term. It is estimated by examining hydrologic
data for as long a time period as possible and then calculating the
probable maximum yield of the raw water supply resource during the
most severe drought, also referred to as the "critical period".
Previous safe yield estimates conducted for the same water supplies
used differing techniques and drought periods to estimate safe yield.
For example, the recent Urban Area Raw Water Management Plan (Black
& Veatch, 1995) used synthesized flow records simulating the period
1942 - 1991, and particularly the drought of 1954 to estimate the yield of
the Rivanna Reservoir. The Report on Water Works System
Charlottesville, Virginia (Polglaze & Basenberg, 1959) used the 1930
drought to predict the safe yield for the Rivanna Reservoir. The Safe
Yield of Municipal Surface Water Supply Systems in Virginia Planning
Bulletin g335 (Virginia State Water Control Board, March 1985) used the
Appendices 36
\XVawil~proje~s'GOSO.~WIa~EI~RTS'uRt~ mmead~d Aiaean~iv~s 4.doc
~ ~ Vana~e I-laagen Brustli~ Inc. Revised Draft May 16, 2001
1953-54 critical 'period to estimate safe yield of the Sugar
Hollow/Ragged Mountain system.
Methods employed for this analysis included a review of United States
Geological Survev (USGS) stream gage data for numerous gauging
stations in the region. This data was used to select representative
hydrologic data and to identify the critical periods for all three water
supply sources noted above. System-wide safe yield evaluations were
performed for the RWSA Urban Service Area system based 'on the 1930
drought, which was found to be the critical period for each o.f the water
supply systems (the Rivanna Reservoir, Sugar Hollow/Ragged
Mountain Reservoir system, and the North Fork Rivanna River). The
system-wide safe yield was estimated by adding the safe yield estimates
for each component of the system. As no data exist to directly evaluate
the effect of the 1930 drought on the Sugar Hollow/Ragged Mountain
reservoir system, estimates of safe yield based on two surrogate
watersheds were used.
The estimated safe yield of the water supply system is currently 11.9 to
12.6 mgd. This range in safe yield results from uncertainty regarding the
1930 safe yield of the Sugar Hollow/Ragged Mountain system. As
siltation reduces storage volume in the reservoirs, this safe yield will
decrease over time. Safe yield for the system in Year 2050 is estimated to
be 4.5 mgd to 4.8 mgd. Current and future safe yield estimates for the
existing raw water supply system and for each component of the system
are summarized below.
RWSA Current And Future System-Wide Safe Yield Estimates
Source Current Safe Year 2050 Safe Yield
Yield
Rivanna Reservoir
Sugar Hollow/Ragged Mtn.
North Rivanna River Intake
Total System
7.2 mgd 0 mgd
4.1 to 4.8 mgd (~) 3.9 to 4.2 mgd o)
0.6 mgd 0.6 mgd
11.9 to 12.6 mgd 4.5 to 4.8 mgd
(1) Range corresponds to uncertainty regarding the 1930 drought event.
Appendices
\\V awiU~orojects~3OS02~R'l'~R~ommend~ Alternatives 4.doc
37
' ~ 'Vana~ Han~n Brusdin. Inc. Revised Draft May 16, 2001
Appendix B: Demand Analysis
Executive Summary
Vanasse Hangen Brustlin, Inc. (VHB) was retained by the Rivanna Water
and Sewer Authority to assist with evaluating their need for future
additional raw water supply sources in order to satisfy the needs of its
customers. As part of this process, VHB is assisting the Authority with
evaluating their existing water supplies, projecting future water demand,
evaluating alternative approaches to address any shortages identified,
and if required, permitting the construction of any new water sources
found to be required. This Water Demand study is the first step in
assisting the Authority to better understand its long term demand as it
carries out its mission of providing adequate, safe and dependable water
supply to its customers.
As the permitting process moves forward, this report will become an
important component of the documentation that will be required to
support the Authority in its efforts to secure adequate raw water supply
for its customers. As such, this report will be subject to detailed review
by individuals, state and federal agencies, and other concerned parties.
As this process moves forward, this study may be revised to respond to
comments and concerns that are raised.
This report presents a comprehensive review of long term water demand
in the region, and is based on the best available data. A design year for
the study has been established as the year 2050. This study presents four
separate approaches to projecting raw water demand. The first approach
looks at historic trends in raw water volumes and projects these trends
into the future. The other three approaches break down total demand
into a series of distinct components, and project demand for each
component into the future. Total demand is the sum of the individual
components of demand. One of these techniques is based on population
trends and per capita water consumption, the second is based on build
out under the comprehensive plans for each of the jurisdictions, and the
third is based on historic trends in each of the components of demand.
The details of all four approaches are presented in the study report.
This study concludes, using all four approaches and the best available
data, that demand can be expected to continue to rise from its current
level to the design year 2050. In addition, it was found that each of the
approaches results in total demand estimates that correlate well with the
other approaches used. Total demand estimates fall within a range of
approximately 20 percent. While these demand estimates result in a
range of values, the study does not conclude that any one approach
results in a better projection than any other approach. As a result, the
study comes to the overall conclusion that total 'water demand in the
year 2050 Will range between 18MGD and 21MGD.
Appendices
\~Vawiil~wjectsL~0502~Wl~,EPOR'I'g~mmeaded Alternat/,,ms 4.doc
38
~r~ Vanasse Hangen Brustrm. Inc. Revised Draft May 16, 2001
Appendix C: Analysis of Alternatives.
Executive Summary
In our efforts to recommend to RWSA a strategy to meet the long-term
water supply needs of its customers, the study team performed a
thorough analysis of alternatives. This process involved first identifying
all potential reasonable measures to bring supply and demand into
balance through 2050. We then evaluated each of those alternatives
against the criteria of effectiveness, practicability/.cost, and
environmental impact. The purpose was to identify the least
environmentally damaging, practicable alternative capable of meeting
projected demand.
The alternatives evaluated included improvements to existing supply
sources as well as development of wholly new sources. Since
sedimentation in the SFRR is the primary factor in dimims' hing water
supplies, efforts to stem siltation were investigated. Also, conservation
and drought management policies were reviewed for their potential to
manage demand. Other efforts to prolong the useful life of SFRR, such
as adding crest controls, were also investigated. Although the SFRR
currently provides the bulk of the raw water for the region, other
existing impoundments at Chris. Greene Lake and Beaver Creek were
analyzed for their water supply potential. Finally, new sources such as
tapping groundwater and constructing new water impoundments were
investigated based on the same criteria.
The result of this analysis was a balanced comparison of possible
improvements, summarized in the matrix on the following pages. This
format allows easy review of key projects benefits and impacts. The
results of the evaluation process, supplemented by follow-up
investigations based on consultation with regulatory agencies and input
from the public, formed the basis for the recommendations included
herein.
To summarize that recommendation, we recommend temporary use of
the revised release, implementation and monitoring of sediment control,
drought management, and voluntary conservation, along with
pursuance of 4' crest controls with an 8 mgd constant release. These
measures represent a package of viable alternatives that appear best to
satisfy applicable considerations. This combination would meet the
needs of the Urban Service Area through approximately 2030, allowing
adequate time to monitor and select future, longer-term measures.
Furthermore, the combination is cost-effective, incurs minimal
environmental impacts, benefits flow in the Rivanna below the dam, and
prolongs the useful life of SFRR.
Appendices
\~V awill'~pr o j~Ofi02~~ mm~ ~l Altm~v~ 4.doc
39
RIVANNA WATER SEWER AUTHORITY
WATER SUPPLY ALTERNATIVES MATRIX
INCREASE IN ESTIMATED ANNUAL UNIT COST POTENTIAL # OF POTENTIAL IMPACTS TO PREVIOUSLY PREVIOUSLY APPROXIMATE
AI,TERNATIVE 2uso SAFE YIELD COST ($) O&M COST ($) (S/g)* RESIDENTIAL IDENTIFIED CULTURAl, RE.~.OURCE~ IDENTIFIED T & E WETLAND IMPACT8
(m~d) ,DISPLACEMENTS STRUCTUEI~ ARCHAEOLOGICAL SPECIES in vicinity (Acres)
Dredge South Fork
Rivanna Reservoir
--Single Event ?.2 $ ? I ,o(x),(ggi nla $9.86 1! 0 0 0
--Annual Dredl~in~ 7.2 $ 7,200,01g) $ 800,000 $1.00 0 0 0 0 5
Reduce Sediment Load
into South Fork
Rivanna Reservoir
--BMPs 2 $ ~,g{XI,IRR! nla $4,40 0 U 0 0
--Land Use Controls 2 $ 16,000,000 nla $11.00, , t) 0 0 0 0
Alternate Release
Scenarios at South
Fork Rivanna Reservoir ].6 $ 386,ti(R) n/a $0.24 O 0 0 0 minimal.
Add 4 fi, Crest Controls on
Soulh Fork Rivanna Dam ? $ 2,260,1X10 nl~ $0.32 O I I James s[flnymusscl
Add 8 fl. Crest Conlrols on
South Fork Rivanua Dam i I $ 18,300,000 n/a $1.66 2 I I James spin,/mussel 39
Use South Fork
Rivanna Reservoir as a
Pumped Storal~e Reservoir u nla nla n/a O 0 0 0 minimal .....
Up lo :5 fl. Drawdown of Chris
Greene Lake 2.9 $ 7,400,000 not significant $2.55 0 0 11 U minimal
20 fl. Draw Down of Chris
Greene Lake S.5 $ 14,700,000 not significant $2.67 0 0 0 Il minimal/leml~orap~t
Usc of Chris Greene Lake
~s a Pumped Storage
Reservoir o nla nla n/a o 0 , 0 0 0 minimal
Use Beaver Creek
Reservoir to Supplement I
Flows in Mechums River o $ Stxt,ooo nnt significant , nla 0 u ti i) minimal
Dredge Sugar Hollow
ConversionReserv°ir of Ragged Mtn. U'l $ 4,900,0~R1 nnl si[lnificant ' $49 0 0 0 0 2 .
to Pumped Storage Reservoir 10 $ 47,(RE),000 not significant $4.70 I 0 0 0 5
'umpback to Mechums
River IS $ 56,0(gt,0~g! $ 15u,tg}O $3.73 0 unknown unknown Iamm spin~/mussal
Pumpback to Moormnns
~River 15 $ 69,000,1100 $ 280,000 $4.60 0 unknnwn unknown James s[~inl,,mussel 5
'Unit cost based only on capital cost per gallon,
Does not Include effecls of annual operations and maintenance costs,
~WILLVA~ROJECTS~3OS02\SHEETS~,3AIternmaIrlx~Sheell
RIVANNA WATER SEWER AUTHORITY
WATER SUPPLY ALTERNATIVES MATRIX
REDUCTION ESTIMATED ANNUAl, UNIT COST POTENTIAL # OF POTENTIAL IMPACTS TO PREVIOUSLY PREVIOUSLY APPROXIMATE
ALTERNATIVE IN COST ($) O&M COST (S/g)* RESIDENTIAl, IDENTIFIED CULTURAL RESOURCES IDENTWIED T & E WETLAND IMPACTS
DEMAND'(mgd) DISPLACEMENTS STRUCTURES ARCHAEOLOGICAL SPECIES in vicinity (Aere~)
Water Conservation
--Plumbing Changeout I. 13 o n/a 0 o 0 0 0 0
-.Pricing Structu re o. 13 unknown n/a n/a 0 0 0 0 ' 0
--Comm.flndustrial o.2~ o n/a 0 0 0 0 o - o
-.Landscaping/Xeriscaplng o n/a n/a n/a o 0 o 0 0
-.Education o. 13 $ 2.500.000 n/a $19.23 0 0 0 0 0
--System Pressure Reduction, o ~a n/a n~a 0 0 0 0 o
Growth
ManaRement 1.7 unknown n/a n/a 0 0 0 0 0
Drought Management
Demand Side 1.4 . $ 250,000 n/a S0.18 0 0 0 0 0
Drought Management
Supply Side I unknown n/n n/a 0 0 0 0
Leak Detection and
Meter Calibration o ' n/a n/a n/a 0 o 0 0 o
*Unit cost based only on capital cost per gallon.
Does not include effects of annual operations and maintenance costs.
\\WILLVA\P ROJ ECTS\3OS02~SH E ETS~3Allemmatrtx~Sh eel I ~2~
RIVANNA WATER SEWER AUTllORITY
WATER SUPPI~Y AI.TERNATIVE$ MATRIX
INCREASE IN ESTIMATED ANNUAL UNIT COST POTENTIAL # OF POTENTIAL IMPACTS TO PREVIOUSLY PREVIOUSLY APPROXIMATE
ALTERNATIVE 2uso SAFE YIELD COST ($) O&M CO.qT ($) (S/gallon)* REXIDENTIAL IDENTIFIED CULTURAL RF~qOURCIF.8 IDENTIFIED T & E WETLAND IMPACTS
(m~d) DISPLACEMENTS STRUCTURF~ ARCHAEOLOGICAL SPECIES tn vlcinlt~t , (Acr~)
Aquifer Storage
& Recovery o .la n/a n/a n/I n/a n/a n/i als
Conventional Withdrawal of
Groundwater o.I $ 1,2oo,ooo n~a $ t2 0 0 0 0 0
Construct Darn on
Buck Mountain Creek 14.4 $ J7,000,000 nol sl[lniflc~mt $3,96 t 6 0 James s~in]/mussel 59 , ,
Collstruct Dam on
Preddy Creek 6.4 $ 91.000,000 not sl~lnlflcant $14.22 6 7 0 0 77
Conslruct Dam on
Moormans River 11.6 $ 106,000,000 not sll~nlflcant $9.14 22 14 I 0
Conslruct Dam on
~lorth Fork Rivanna River i5.4 $ 79~000.000 not ~lliMflcant $5.13 2 3 4 Jamet spin,mumm/ 72
Construct Dam on
Mechums River
Near Lake Albemarle I;!,3 $ 68,000.000 not $1(Inll'icant $5. [ I 21 lJ 2 James s~fl~,mulsel 144
Construct Dam on
Mechums River
~lear Midway 5.6 $ 26,000,000 not si[Inlficant S4.64 § 6 0 Jame~ splat'mussel 52
~'.onstruct Dam on
Buck Island Creek 15 $ I IS,OOO,OOO not sl~nillcnnl $7.S7 14 6 0 0
lames River Withdrawal
it Scotlsville 15 $ 72,~00,000 $ I?0,000 $4.80 0 unknown I unknown
Rivanna River
Withdrawal 4.7 $ 18,0~0,000 not sl~lniflcanl $3,83 0 unknown unknown 0 2
Mechums River
Withdrawal 0.2 $ 850.000 not sl~nificant $4.25 0 unknown unknown Jlm~ spln~trnusmi minimal
INCREASE F~'TIMATED ANNUAl. UNIT COST POTENTIAl. # OF POTENTIAl. IMPACTS TO PREVIOUSLY PREVIOUSLY APPROXIMATE
ALTERNATIVE IN COST ($) O&M COST ($) ($/1)* RESIDENTIAl. IDENTIFIED CULTURAL RESOURCES IDENTIFIED T & E [ WETLAND IMPACTS
DEMAND (mild) DISPLACEMENTS STRUCTURES ] ARCHAEOLOOICAL SPECIES in vlchUt~tt[ (Acres)
Regional
I
C,ooperation :~ $ 3,1UU,O00 n/a nfs 0 unknown ] unknown 0 minimal
REDUCTION ESTIMATED ANNUAl. UNIT COST POTENTIAl. # OF POTENTIAl. IMPACTS TO PREVIOUSLY PREVIOUSLY APPROXIMATE
ALTERNATIVE IN COST ($) O&M COST ($) ($11)* RESIDENTIAL IDENTIFIED CULTURAL RESOURCES IDENTIFIED T & E WETLAND IMPACTS
SAFE YIELD (m~d) DISPLACEMENTS STRUCTURES I ARCIIAEOLOGICAL SPECIES in vicinity, (Acres)
No-Action 7.7 n/a n/a n/a 0 0I 0 0 0
*Unit cost based only on capital cost per gallon.
Does not Include effects of annual operations and maintenance costs.
~Wl LL v A\P R[~I ECTR~.'10.~O~RH F FT .e;Lq AIt~ m m at d~g ht~t '1
~ Vat. se Han~en B~, inc. Revised Draft May 16, 2001
Appendix D: UOSA Analysis
From: Plato Chen cc: TE Durum
Re: UOSA Reclamation Plant information GB Rest
File: 5036.022 #3
Date: May 16, 2001
This memorandum is written to document information collected regarding the Upper Occoquan
Sewage Authority (UOSA) Reclamation Plant which may be applicable to the Rivanna Water and
Sewer Authority's current planning study. The information was provided by Glen Palen of
CH2M' Hill, which has been involved in a number of the plant expansions including the current
one. Glen provided the following information:
1. The plant has been built and expanded in a number of different construction projects. The
projects have included Project 15, Project 27, Project 32, and Project 54 (on-going). The
number for each project represents the capacity of the plant after completion of the project.
2. Since the initial construction of the plant, the treatment process has basically been unchanged
with the exception of modifications for biological nutrient removal (BNR). The treatment
process consists of primary treatment, secondary treatment, high lime (pH) treatment (for
disinfection), recarbonation, media filtration, GAC adsorption, media filtration (for removal
of GAC fines), chlorination, and dechlorination. Modifications for BNR were made in one'of
the more recent projects.
3. The selection of this treatment process was based on the objective of meeting the initial
discharge permit requirements (established in the 1970s), which include the following limits:
TSS < 1 mg/L; COD < 10 mg/L; MBAS < 0.1 mg/L; turbidity < 0.5 NTU; and coliform <
2/100 ml. These limits have not been changed since inception of the plant. There axe also
two nutrient level limits: TKN < 1 mg/L; phosphorus < 0.1 mg/L.
4. The current project (Project 54) ii an expansion of the plant from 32 MGD to 54 MGD, and it
consists primly of the addition of "mirror-image" process units to provide increased
capacity (no significant modifications are being made to existing units). The estimated
construction cost of this project is somewhere in the range of $200 to $250 million, or
roughly on the order of $10/gpd capacity. This cost includes all of the treatment processes in
both the liquid and solids trains. Information was not collected to indicate how this cost
breaks down between the different process units. However, based on our experience for this
size plant, a figure of somewhere in the range of $1/glxl to $3/gpd would probably be
consistent with the current UOSA project costs for the addition of unit processes which are
not currently part of the Rivanna Water and Sewer Authority's WWTP (i.e., tertiary
processes such as high lime treatment, recarbonation, media filtration, and GAC adsorption).
5. It should be noted that the original permit for the UOSA facility was established under then
prevailing water quality criteria, and it has not been changed because of statutory provisions.
Significant changes in drinking water regulations (particularly related to concerns over
pathogenic protozoans such as Giardia and Cryptosporidium) since that time could influence
the Virginia Department of Health' s opinion of the appropriateness of a similar permit for the
Rivanna Water and Sewer Authority.
Appendices
\\V awill~r o]ect ~O~¢Y~,WI~R~ PORTS~Reco mmend~ A.It~aafives 4.doc
40
Vanas.~ Hartgen Brostlin, Inc.
Revised Draft May 16, 2001
Bibliography
Note: A thorough bibliography for the Analysis of Alternatives is included
in that document. ~ section cites, the supplemental documents
referenced herein.
City of Asheville, NC, Water Resources Department web page. Regional
Water Authority "Drought Performance."
http: //www .ci_ a ~heville .nc .us / water ! annual.btm
City of Greensboro, NC, Water Conservation Program- "City of
Greensboro Water Fact Sheet." January 13, 1999.
http:/[www.ci.greensboro.nc.us/wateres/H2Oconserv/waterfaq.htm
Letter of January 10, 2001, from Ronald E. Conner, P.E., Virginia
Department of Health, to Mr. Arthur Petrird, RWSA.
Memorandum of May 15, 2000, from Stephen Bowler and David
Hirschman, Albemarle County, to Karin Ertl, VHB.
New Mexico Water Conservation Alliance. Conservation Current. Spring
1999. "Water Budgeting Achieves Results:"
http: //wrri.nmsu.edu/wrdis/conserve/news/.s-pring99/current.html
Bibliography
~,Wawilhpmjec~..~50~ ~WP~REPOR'I'S~ o mmended Altem~ve~ 4.doc
41