Method of wastewater flow measurement, system analysis, and improvement

• US 8,447,533 B1
• Filed: 10/12/2010
• Issued: 05/21/2013
• Est. Priority Date: 10/13/2009
• Status: Active Grant

• Current Assignee: Eastech Flow Controls, Inc.
• Original Assignee: Eastech Flow Controls, Inc.
• Inventors: Sinclair, Franklin, Williams, David D.
• Primary Examiner(s): SUGLO, JANET L
• Application Number:
  US12/902,218
• Time in Patent Office: 952 Days
• Field of Search: 702/45, 702/55, 702/156, 702/166
• US Class Current: 702/45
• CPC Class Codes: E03F 2201/20 Measuring flow in sewer systems
• CPC Class Codes: E03F 7/00 Other installations or implements for operating sewer systems, e.g. for preventing or indicating stoppage; Emptying cesspools

Abstract

A method of reducing rainwater and/or groundwater inflow and infiltration into a wastewater treatment collection grid. The method preferably involves the steps of (a) dividing the grid into a plurality of major subsystems, (b) determining flow depth levels in each major subsystem under dry and wet conditions, (c) using these wet weather and dry weather flow depth measurements to determine a volume flow ratio for wet versus dry conditions, (d) using these flow ratios to identify the particular major subsystem(s) in which the greatest amount of inflow or infiltration is occurring, and then (e) further dividing the highest ranking major subsystem(s) into smaller subsystems in which the same dry and wet weather level measurement and ranking analysis is preferably conducted to further isolate problem locations for surveillance, maintenance, and/or repair.

Claims

1. A method of reducing rainwater or ground water inflow or infiltration into a wastewater collection grid comprising the steps of

(a) identifying a wastewater collection grid having a configuration comprising a plurality of manholes;

(b) dividing said wastewater collection grid into a plurality of major subsystems, said configuration of said wastewater collection grid being such that each of said major subsystems has one of said manholes at an outlet end thereof;

(c) installing flow depth level detectors in said manholes at said outlets ends of said major subsystems;

(d) using said flow depth level detectors to determine for each of said major subsystems a ratio (Δ

Q) of wet weather volume flow rate to dry weather volume flow rate by;

(i) measuring for each of said major subsystems using said flow depth level detectors a dry weather flow depth level (Dd) for flow during dry weather conditions;

(ii) measuring for each of said major subsystems using said flow depth level detectors a wet weather flow depth level (Dw) for flow during wet weather conditions or during a combination of wet weather and dry weather conditions;

(iii) using said dry weather flow depth levels (Dd) measured by said flow depth level detectors to determine for each of said major subsystems a dry weather cross-sectional area of flow (Ad);

(iv) using said wet weather flow depth levels (Dw) measured by said flow depth level detectors to determine for each of said major subsystems a wet weather cross-sectional area of flow (Aw); and

then

(v) determining for each of said major subsystems said ratio (Δ

Q) of wet weather volume flow rate to dry weather volume flow rate according to a formula

2. The method of claim 1 wherein step (f) comprises:

(A) dividing said highest ranking one of said major subsystems identified in step (e) into a plurality of smaller subsystems, said configuration of said wastewater collection grid being such that each of said smaller subsystems has one of said manholes at an outlet end thereof;

(B) installing flow depth level detectors in said manholes at said outlets end of said smaller subsystems;

(C) using said flow depth level detectors installed in step (B) to determine for each of said smaller subsystems a ratio (Δ

SQ) of wet weather volume flow rate to dry weather volume flow rate by;

(1) measuring for each of said smaller subsystems using said flow depth level detectors installed in step (B) a dry weather flow depth level (SDd) for flow during dry weather conditions;

(2) measuring for each of said smaller subsystems using said flow depth level detectors installed in step (B) a wet weather flow depth level (SDw) for flow during wet weather conditions or during a combination of wet weather and dry weather conditions;

(3) using said dry weather flow depth levels (SDd) measured by said flow depth level detectors installed in step (B) to determine for each of said smaller subsystems a dry weather cross-sectional area of flow (SAd);

(4) using said wet weather flow depth level (SDw) measured by said flow depth level detectors installed in step (B) to determine for each of said smaller subsystems a wet weather cross-sectional area of flow (SAw); and

then

(5) determining for each of said smaller subsystems said ratio (Δ

SQ) of wet weather volume flow rate to dry weather volume flow rate according to a formula

3. The method of claim 2 wherein step (E) comprises conducting camera surveillance within said highest ranking one of said smaller subsystems to locate said points of inflow or infiltration of said rainwater or ground water in said highest ranking one of said smaller subsystems.

4. The method of claim 2 wherein, in step (D) said Δ

SQ ratios are used to identify a subset of said smaller subsystems which rank highest in contributing to said highest ranking one of said major subsystems a greater volume amount or cost amount of said rainwater or ground water and which together account for from about 50% to about 80% of a total volume amount or cost amount of said rainwater or ground water received by all of said smaller subsystems.

5. The method of claim 2 wherein said method further comprises the steps of removing at least some of said flow depth level detectors installed in steps (c) in said manholes at said outlet ends of said major subsystems and re-installing in step (B) at least some of said flow depth level detectors removed in said step of removing in said manholes at said outlet ends of said smaller subsystems.

6. The method of claim 1 wherein step (e) further comprises the steps of:

(1) determining from survey data an estimated number of residents served by each of said major subsystems;

(2) determining for each of said major subsystems an estimated dry weather wastewater volume flow rate (Qd) based upon said estimated number of residents served by said major subsystem; and

(3) determining for each of said major subsystems a wet weather volume flow rate (Qw) by multiplying said estimated dry weather wastewater volume flow rate (Qd) for said major subsystem by said Δ

Q ratio for said major subsystem.

7. The method of claim 6 wherein step (e) further comprises the step of determining for each of said major subsystems a volume amount of rainwater or ground water contributed by said major subsystem to said wastewater collection grid by subtracting said estimated dry weather wastewater volume flow rate (Qd) for said major subsystem from said wet weather volume flow rate (Qw) for said major subsystem.

8. The method of claim 1 further comprising the step of repairing or improving at least one of said points of ground water or rainwater flow or infiltration.

9. A method of reducing rainwater or ground water inflow or infiltration into a wastewater collection grid comprising the steps of:

(a) identifying a wastewater collection grid having a configuration comprising a plurality of manholes;

(b) dividing said wastewater collection grid into a plurality of major subsystems, said configuration of said wastewater collection grid being such that each of said major subsystems has one of said manholes at an outlet end thereof;

(c) installing flow depth level detectors in said manholes at said outlet ends of said major subsystems;

(d) using said flow depth level detectors to determine for each of said major subsystems a ratio (Δ

Q) of wet weather volume flow rate to dry weather volume flow rate by;

(i) measuring for each of said major subsystems using said flow depth level detectors a dry weather flow depth level (Dd) for flow during dry weather conditions;

(ii) measuring for each of said major subsystems using said flow depth level detectors a wet weather flow depth level (Dw) for flow during wet weather conditions or during a combination of wet weather and dry weather conditions;

(iii) using said dry weather flow depth levels (Dd) measured by said flow depth level detectors to determine for each of said major subsystems a dry weather cross-sectional area of flow (Ad);

(iv) using said wet weather flow depth levels (Dw) measured by said flow depth level detectors to determine for each of said major subsystems a wet weather cross-sectional area of flow (Aw);

(v) determining for each of said major subsystems said ratio (Δ

Q) of wet weather volume flow rate to dry weather volume flow rate according to a formula

10. The method of claim 9 further comprising the steps of:

(h) dividing each of said major subsystems in said subset of said major subsystems into a plurality of smaller subsystems, said configuration of said wastewater collection grid being such that each of said smaller subsystems has one of said manholes of an outlet end thereof;

(h) installing flow depth level detectors in said manholes at said outlet ends of said smaller subsystems;

(i) using said flow depth level detectors installed in step (h) to determine for each of said smaller subsystems a ratio (Δ

SQ) of wet weather volume flow rate to dry weather volume flow rate by

(1) measuring for each of said smaller subsystems using said flow depth level detectors installed in step (h) a dry weather flow depth level (SDd) for flow during dry weather conditions;

(2) measuring for each of said smaller subsystems using said flow depth level detectors installed in step (h) a wet weather flow depth level (SDw) for flow during wet weather conditions or during a combination of wet weather and dry weather conditions;

(3) using said dry weather flow depth levels (SDd) measured by said flow level depth detectors installed in step (h) to determine for each of said smaller subsystems a dry weather cross-sectional area of flow (SAd);

(4) using said wet weather flow depth levels (SDw) measured by said flow depth level detectors installed in step (h) to determine for each of said smaller subsystems a wet weather cross-sectional area of flow (SAw); and

then

(5) determining for each of said smaller subsystems said ratio (Δ

SQ) of wet weather volume flow rate to dry weather volume flow rate according to a formula

11. The method of claim 10 wherein, for each of said major subsystems in said subset of said major subsystems, step (k) comprises conducting camera surveillance within said highest ranking one of said smaller subsystems to locate said points of inflow or infiltration of said rainwater or ground water.

12. The method of claim 10 wherein, for each of said major subsystems in said subset of said major subsystems, said Δ

SQ ratios are used in step (j) to identify a subset of said smaller subsystems in said major subsystem which rank highest in contributing to said major subsystem greater volume amounts or cost amounts of said rainwater or ground water and which together account for from about 50% to about 80% of a total volume amount or cost amount of said rainwater or ground water received by all of said smaller subsystems in said major subsystem.

13. The method of claim 10 wherein said method further comprises the steps of removing at least some of said flow depth level detectors installed in step (c) in said manholes at said outlet ends of said major subsystems and re-installing in step (h) in said manholes at said outlet ends of said smaller subsystems at least some of said flow depth level detectors removed in said step of removing.

14. The method of claim 10 wherein step (e) further comprises the steps of:

(1) determining from survey data an estimated number of residents served by each of said major subsystems;

(2) determining for each of said major subsystems an estimated dry weather wastewater volume flow rate (Qd) based upon said estimated number of residents served by said major subsystem; and

(3) determining for each of said major subsystems a wet weather volume flow rate (Qw) by multiplying said estimated dry weather wastewater volume flow rate (Qd) for said major subsystem by said Δ

Q ratio for said major subsystem.

15. The method of claim 14 wherein step (e) further comprises the step of determining for each of said major subsystems a volume amount of rainwater or ground water contributed by said major subsystem to said wastewater collection grid by subtracting said estimated dry weather wastewater volume flow rate (Qd) for said major subsystem from said wet weather volume flow rate (Qw) for said major subsystem.

16. The method of claim 14 wherein step (j) further comprises the steps of:

(1) determining from survey data an estimated number of residents served by each of said smaller subsystems;

(2) determining for each of said smaller subsystems an estimated dry weather waste water volume flow rate (SQd) based upon said estimated number of residents served by said smaller subsystem; and

(3) determining for each of said smaller subsystems a wet weather volume flow rate (SQw) by multiplying said estimated dry weather wastewater volume flow rate (SQd) for said smaller subsystem by said Δ

SQ ratio for said smaller subsystem.

17. The method of claim 16 wherein step (j) further comprises the step of determining for each of said smaller subsystems a volume amount of rainwater or ground water contributed by said smaller subsystem to said wastewater collection grid by subtracting said estimated dry weather wastewater volume flow rate (SQd) for said smaller subsystem from said wet weather volume flow rate (SQw) for said smaller subsystem.

18. The method of claim 9 further comprising the step of repairing or improving at least one of said points of ground water or rainwater flow or infiltration.