ARWA Update

I will be out of the office tomorrow and will not have access to update the blog. On Wednesday I will start posting the November data here and the October data will be added to the historical data on the ARWA web site.

Last week a citizeen called looking for a depiction of the water cycle or hydrologic cycle. I sent her a depiction I found at http://ga.water.usgs.gov/edu/watercycleprint.html. There are numerous depictions of the hydrologic cycle available on this website if you need them. The U.S. Geologic Survey (USGS) is a great source of water related information and I highly recommend checking their website first any time you are looking for that type of information.

ARWA Reservoir Levels

Yesterday afternoon Dominion Virginia Power asked the hydro-electric facility to shut down while they began work replacing three storm-damaged power poles along Chesdin Road. When they tried to restart last night they were not successful and had to wait to make repairs this morning. Similar starts and stops of the hydro-electric facility for equipment issues is why the graph below of the downstream river flows for the last seven days has such large fluctuations in flow.

 

ARWA Update

One of the reasons we started this blog is to provide information to interested citizens on a regular basis so I must apologize that I have not posted anything in 7 days.

Last Thursday afternoon was taken up with Board meetings for both Appomattox River Water Authority and South Central Wastewater Authority. Since then we have been working on selecting a replacement for the boiler that provides heat to one-half of the treatment plant, the Laboratory, and the Administration offices.

The third item we have been working on since the Board meeting is the evaluation of potential products to replace our current corrosion inhibitor. We determined the current product was not as effective as it should have been in removing manganese from our finished water during recent manganese events which contributed to some customers experiencing discolored water. Changing a treatment chemical begins with looking at lots of information to make sure you select a product as good as, and hopefully better than, the current product used. That selection is followed by a lot of testing and evaluation of results to confirm the water quality is improved before we purchase the required quantities of the product.

We are also exploring two other solutions to address the elevated manganese levels in our raw water that occur following storm events. I will describe them in more detail in future posts to this blog. We will implement all of them, if they work, as multiple barriers to manganese to ensure our Operators have the tools necessary to address that issue when it occurs. Changes such as these require attention to lots of details to ensure we deliver the highest quality water to our customers throughout the effort to make the changes.

If you momitor the lake level at your property, or monitor river flows below the reservoir, you have probably noticed there has been a lot of variation in both over the past week. These variations were related to equipment issues associated with the hydro-electric facility located at the Brasfield Dam. Even with these variations in flow we always satisfied our permit release requirements.

ARWA Update

The rain we are receiving today has already arrested the declining river flows at the upstream gauges and should cause the flows to increase if it continues long enough.

Earlier this Summer we experienced a problem with taste/odor in our finished water followed shortly thereafter with a discolored water event. The taste and odor issue was caused by our response to a sudden increase in algae in the reservoir. We treated closer to the intakes than we normally do and we learned to monitor algae more frequently to catch future increases sooner so we can treat farther away from the intakes with less algaecide.

The discolored water was caused by manganese, which occurs naturally in the raw water and rises following a rain event. We conducted a study of alternative filter media in 2009 and 2010 to determine if it would remove manganese better than our current media. The results of that study show that we do not normally have enough manganese in our raw water to condition that media so it will work better than our current media when we have a manganese spike following a rain event. The consultant recommended some alternatives and we are working on a request for proposals to investigate one of those alternatives, in-reservoir aeration near our intakes. This alternative will take some time to implement. We are proceeding, however, with investigating two other alternatives to increase the number of barriers our treatment process will provide to reduce the manganese levels in our finished water. The first is to feed an oxidizing agent we already use at a second location during a manganese event. The other is an investigation of alternative corrosion control agents to deal with any manganese that reaches that stage of our treatment process. We will keep you posted on the results of all of these investigations.

Chesdin Reservoir Level Update

Now that river flows are declining following last week's rain event we are once again seeking the right release through the hydro-electric facility to take full advantage of the flow into the reservoir to generate power but not draw the reservoir down below the spillway. Yesterday's inflow, using the current formula specified in the Virginia Water Protection Permit, was 770 cfs (498 million gallons per day) which is equivalent to 5.5 inches of water flowing over the spillway. The flow past the Matoaca gauge at 9:45 this morning was 589 cfs (381 million gallons per day) which is equivalent to 4.5 inches flowing over the spillway yet this morning the reservoir level was 1.5-inches below the spillway on the dam. The operators of the hydro-electric facility are reducing their flow with the goal of maintaining the reservoir level at the spillway. They will continue in this mode until they need to drop below the minimum flow required to turn their turbine. At that point they will cease operating and water will resume flowing over the spillway.

Reservoir Update

The reservoir level recovered quite rapidly last Friday and we were able to close the cone valve around 2:00 p.m.. so all the flow would go over the spillway. The reservoir level continued to rise over the weekend. This morning he flow past the Matoaca gauge downstream, 1130 cfs, is the equivalent of a little more than 7 inches of water over the spillway. The actual flow over the spillway is only 2 inches because the hydro-electric facility is releasing the difference to generate electricity.

Reservoir Level Update

This morning the reservoir level was two inches below the spillway (-2 inches) which is two inches higher than yesterday morning. The consultant completed the IFIM studies they were performing this week shortly before noon yesterday so we resumed releasing flow based on the estimated inflow for the previous day. Yesterday's estimated inflow was 409 cfs (264 million gallons) which means we only have to release 190 cfs (123 million gallons) today. After subtracting an estimated 45 cfs for raw water withdrawals this still leaves 174 cfs (112 million gallons) that will be stored in the reservoir. This should raise the reservoir level about 1.5 inches today. Therefore the reservoir level should exceed the spillway level sometime tomorrow at the latest. Once water is flowing over the spillway the hydro-electric facility can resume operation and generate power with the water flowing to the downstream portion of the river.

IFIM Update

Yesterday the consultant performing the field work collecting river dat for the IFIM study completed 8 of the 10 locations on the river. This morning they completed the remaining 2 locations and recently notified us that we can resume releasing the down stream flow required by the Virginia Water protection Permit and/or the Hopewwell Agreement.

Resuming the required releases means the reservoir level will stay where it is until the increased river flows from the rain that started on Tuesday reach the reservoir. The current flows past the Farmville gauge are greater than the highest historical flows recorded on this date in the past 84 years. Those flows will reach the reservoir in 2 to 3 days and fill the reservoir completely.

IFIM Update

Yesterday the consultant completed the 150 cfs flow stage of data collection at the selected locations on the study portion of the river. ARWA staff reduced the release flow last night so the consultant could start on the 50 cfs flow stage today. This morning the reservoir level was already one-inch higher than yesterday morning. This level will continue to recover about an inch a day while this flow stage is performed. The rains today have increased the river flows at the upstream gauging stations. These flows will reach the reservoir in 2 to 3 days and should completely fill the reservoir after the current flow stage is completed.

IFIM Study Field Work

This morning the consultant performing the In-stream Flow Incremental Mthodology (IFIM) study needed for our application for a permanent modification of our Virginia Water Protection Permit, and the associated down stream release schedule, began the second and, weather permitting, third flow stages to collect data at the ten (10) transect locations. The river flow target for the second stage is 150 cfs (97 mgd) and the flow stabilized at 166 cfs (107 mgd). The estimated inflow to the reservoir today, based on the flow past the upstream gauges yesterday, is 231 cfs (149 mgd). The raw water withdrawals from the reservoir today are averaging in the low to mid forty million gallons per day which is approximately 65 cfs. This means the sum of water released for the IFIM study and withdrawn to meet customer demands equals the inflow and the reservoir level should not change much today or probably tomorrow. The inflow will not decrease significantly by the time the consultant completes the 150 cfs stage and we reduce the release rate to 50 cfs so the reservoir level will recover several inches while that stage is underway. The reservoir level will recover even more if there is much rainfall in the Appomattox River watershed tomorrow and Wednesday.

There is one more segment of data gathering for the IFIM study and that is referred to as a Demonstration Flow Assessment or DFA. The DFA is a team-based study used for portions of a river that cannot be evaluated using transects to measure the physical nature of the river at selected locations. In the case of our study the DFA will be applied to a highly divided portion of the river below the Abutment Dam. This study will be run at four (4) different flow rates (40, 80, 120, and 190 cfs have been suggested) which will take several days. Once the team members have been identified for this study the work will be coordinated between their individual schedules and ARWA's ability to control the river flows.

Once the field data collection is complete, that information will be used to determine the effects of various release flows on the aquatic habitat in the river as well as other beneficial uses of the river (including public water consumption and recreation). All of this information will then be evaluated and included in the proposed release schedule that the Authority will submit to the Virginia Department of Environmental Quality (DEQ) as part of the request for a permanent modification of ARWA’s Virginia Water Protection Permit 01-1719.

Any action the DEQ decides to take concerning our requested permit modification will be advertised for public comment, and possible public hearing, before the record can be considered complete and sent to the State Water Control Board for approval. We will use this blog, and the ARWA website, to keep everyone interested in this process informed of what is happening concerning our request.

October 7, 2011 IFIM Study Update

Our consultant plans on performing the next two flow stages of the data collection for the IFIM Study next week (October 10 - 14, 2011). The two flow rates are 150 cubic feet per second (cfs), or 97 million gallons per day (mgd), and 50 cfs or 32 mgd. During these tests we need to control the flow released to the lower portion of the Appomattox River within 5 cfs of the target flows. Since we expect the natural inflow into the reservoir to be higher than 150 cfs during the study period next week we have to draw the reservoir level down below the spillway on the dam by approximately 3 inches to provide sufficient space in the reservoir to store the inflow that exceeds our required release amount. During the 150 cfs stage on Monday and Tuesday the release amount plus the amount withdrawn for treatment should be about equal to the inflow so the reservoir level should remain very close to 3 inches below the spillway. When we reduce the release amount to 50 cfs for the second stage the reservoir level should recover and may be full again when this portion of the study ends sometime next Thursday.

The operator of the hydro-electric facility at the Brasfield Dam completed the maintenance work on their facility this afternoon so they will release the additional flow needed to draw the reservoir down by Sunday evening for power generation. They require more than 150 cfs to generate power so they will have to shut down during the IFIM Study work next week and we will release the water during the study efforts.